LEC vs LED Grow Lights: Side-by-Side Cannabis Grow Journal

by Nebula Haze

This grow journal features two indoor cannabis gardens that are identical except for one thing: the grow light! See a match-up between LEDs vs LEC grow lights. If you’re unfamiliar, LEC is a brand name by Sun System. LECs are also known as CMH grow lights. I have to admit, I was surprised by the results. I compiled these live grow journal entries from posts on my Instagram account and excerpts from our weekly free newsletter. I also included some interesting comments I received along the way. I hope you enjoy 🙂


Table of Contents


Grow Experiment Details & Setup

Quick Summary

6 Mom Plants with All their Clones (I chose two matching clones from each plant for the experiment)

Grow Lights

Grow Journal

Now that you’ve seen the details, let’s get started!

Choosing Clones

December 16, 2019

Family portrait! 📸 Check out these 6 bonsai mom plants and their babies.

I took a bunch of extra clones because I want to make sure I get a well-matched pair from each plant.


I’m picking two clones from each mother plant to use in a side-by-side grow between a 315 LEC vs HLG 300 Quantum Board LED grow light.

Each setup will be identical besides the grow light: a 2x4x6 grow tent, 3-gallon pots full of Mother Earth coco coir, and the Flora trio plus CaliMagic as nutrients.

Next, the winning clones will be transplanted and put into their tents. Then the excitement begins!

Comments from readers

  • “The quantum boards do make amazing bud, only downside is that the HID has much better penetration. So the LED umols drop off quickly. Top buds will be top shelf while lower you get mids. Lollipop and defoliate the LED plants HARD!” ~jhb420guy
    • Jhb420guy ended up being right! ~Nebula


Vegetative Stage

December 26, 2019

I wanted to share my first impressions of the LEC vs LED grow lamps. First, my eyes dislike the high-UV light from the LEC bulb. What’s worse, the LEC doesn’t have an auto switch-off feature, which means I have to wait 10 minutes after unplugging the LEC to plug it back in or it won’t spark. As a result, I can’t turn the LEC light off and on to quickly peek on the plants. In contrast, the LED can be turned on and off easily and the light seems much gentler on my eyes anyway.

315 LEC on top, HLG 300 Quantum Board R-spec LED on bottom.

Side note: My eyes are more sensitive than normal. I didn’t wear any eye protection for the first several years of indoor growing and it caught up with me. Don’t make the same mistake! Turn your lights off or wear sunglasses/snow goggles in the grow area. Your eyes are worth it!

The LED is also a much smaller and lighter fixture that’s easier to pick up, move, and adjust. Based on the LED light being more comfortable to my eyes, its lower electricity usage, and its ability to be turned on and off immediately, I’d say the LED has made a better first impression. The LEC feels more “industrial” like it should be used in a grow operation, while the LED seems sleek, polished, and aimed at home growers. But the plants will be the real judges!

Comments from readers

  • “I recently did almost this exact same experiment. Almost identical lights, mine is last years HLG 300 v2 ( no added red diodes, 3000k) 2 phenos of the same strain, but run back to back, not concurrently. My results were the led won on weight, hands down, 12z from led 9 from CMH. BUT the CMH finished in 7 weeks, where the led took 8. The extra week of growth I’m sure contributed. The quality factor goes hands down to the CMH. Everyone who has sampled from both batches agrees, the CMH grown has better terps and frost. I tested the first batch at 19 and 20% ( 2 phenos) I haven’t gotten potency results from the second batch yet, but my “towelie meter” would guess it’s probably about a 3% bump… One other factor to consider…the CMH tent should be run at mid 70’s f to perform at its best, while the LED needs to be more like 82 to be in its optimal range.” ~skunk_beard
  • “I’m going to go with the LED for overall quality but the LEC definitely increases Terps because of the shock from too much of the blue light spectrum🙌” ~craftcannamike


January 4, 2020

Plants are now in their tents. I’ve kept each clone matched with its sister as far as position in the tent for easier comparison.

HLG 300 Quantum Board LEDs vs 315 LEC grow light. QB on top, LEC on bottom.

These clones were grown out under fluorescent lights in solo cups, and were transplanted to their final homes 3 days ago on New Years. I took 6-10 clones from each mother plant and chose the two best-matching clones from each mom to put in the tents. I’m pretty happy with how well-matched they are. This is going to be an exciting experiment!

They’ll be grown for 4 more weeks (or until they reach 12″ tall, which is half the final size that can be supported in the 6 foot tall tents), then flowered!

Which light will perform better?

There’s a little droopiness on a few plants, I think mainly from being transplanted into bigger pots, and some yellow leaves from when they were first cloned, but overall they look super green and happy under the new lights.

The lights are both 2.5 feet away as the plants adjust to their new space, but for the vegetative stage they should be 18-24″ away so I’m moving the lights down in another few days once I feel the plants seem like they’re happy and growing well.


January 7, 2020 – Tying Down Plants & Plant Training

A big part of training cannabis plants for bigger yields is having the ability to tie down branches into the position you want. This allows you to create the flat table-top plant shape that helps plants get the most and biggest buds from indoor grow lights.

Notice how all the plants in these pictures are about the same height. I’ve been bending and tying down any errant branches getting taller than the rest so they’re all at about the same level.

It’s a small room so I couldn’t move back any further to get the edges of the tents, but here are both tents in one picture (Left is LEDs, Right is LEC)

I love flexible plant twist tie for wrapping around the branches. It’s cheap and comes on a spool with cutter so you can easily get whatever length you want. It’s made specifically for this purpose.

I use plant twist tie to easily tie down branches (it’s made specifically for this purpose)

Use plant twist ties to secure your stems in place

But here’s the real mystery: What’s the best way to fasten the twist tie to the sides of the pot?

Typically I use safety pins (I use fabric pots) but the issue with them is they get rusty so they’re hard to reuse. I ran out of safety pins yesterday and found some hair clips that seem to get the job done, though they don’t clasp very hard.

I’ve seen growers use binder clips. One time I saw a grower insert grommets into their fabric pots. Someone should sell pots like that!

Another common tactic is to insert a tomato ring into the soil. This puts hoops around the outside of your plant, which provides structure and a great place to hold down any twisty tie.

I need your help so I can make a comprehensive list of options for our LST/training page. What do you use to hold down your branches? Leave your answer in the comments!


Comments from readers (Some amazing ideas here! ~Nebula)

  • “You can stab paper clips through the fabric just like a safety pin!” ~cannabiscultivation_
  • “I just rip a little of the green rubber from my ties and poke them straight through my fabric pots.” ~devlotus
  • “Tie a string around the pot. Then use that ring of string as the anchor to tie down the branches.” ~killah_chef
  • Office clips with or without green twisty.” ~jsjsjarkfeld
  • “I just jacked a bunch of pipe cleaners from my wife’s craft room! They work great, and she shouldn’t notice until valentines. Lol” ~seedstarter2019
    • This comment made me laugh! ~Nebula
  • “I use U shaped gardening pegs, push them in the soil and act as great anchors and you can even used them to bend your stems around.” ~kfchhfhxchio
  • “I’ve been bending the whole plant over at a 45 degree angle using bamboo poles and plant ties.” ~naturesessentialscbd
  • “I use and reuse small safety pins and have great results.” ~maxshowdog
  • Solid strand electrical wire works great, coated in rubber so it’s soft and flexible” ~bipolar.grower.13
  • “Wire a cross of bamboo to the pot or paper clams on the edge of the pot. … For mainline or LST the bamboo cross has shown a more even growth, as I could start the tie down closer to the stalk. Seems to keep an even tension as the plant grows.” ~mrbriley11
  • “I just poke a little (holes) hole in my smart pot and thread the training wire through it & short twist to secure. Poke as I go/ as needed. And the pot does not rip or tear. Sometimes I can use the same hole for 2 wires. Plain, simple & easy.” ~papillonx3
  • “I got a fabric eyelet punch, so it pops a hole in and then you can put a metal eyelet in so it doesn’t rip.” ~diakos
  • “My wife will wonder where all of her hair clips have gone.” ~stevetheganjafarmer


January 10, 2020

Quantum Board LEDs vs LEC/CMH update!

Top shows the HLG 300 Quantum Board LED tent. Bottom is the 315 LEC grow light tent.

Here they are with lights on

Full picture of the LED tent

And the 315 LEC tent

So far there really isn’t a difference that I can’t tell between the two tents. The clones are in the same place in each tent for easy comparison.

Today I lowered both lights from 26″ to 24″ away from the tops of plants. I’ll see how they react tomorrow!

So far I’m really enjoying both lights 😊

Comments from readers

  • “Hi Nebula, great journal as usual… Do you have the pots in trays or something for runoff?” ~david_a_knight
    • “They’re in 1020 plant trays on a slight incline (I put a little 1/4″ piece of plastic under the trays in the back). That causes all the runoff water to gently pool forward where I can collect it with a wet vacuum.” ~Nebula


January 11, 2020 – LED Grow Tent

What’s the optimum distance to keep LEDs from plants?

In my experience, it depends on the model of LED, the growing environment, nutrient regimen, whether you’re monitoring the pH, and your particular plants/genetics. Anything that causes stress makes plants more sensitive to light intensity, while plants in perfect conditions thrive at higher light levels.

My HLG 300 Quantum Board LED grow light (R-spec V2) is pictured here. I currently have it about 24 inches (61 cm) from the tops of plants. That’s the distance recommended by the manufacturer for the vegetative stage.

I plan to let plants grow up to the light until their leaves start praying hard (plants putting their leaves up is a sign of high light levels), then move it up just an inch at a time throughout the grow.

I want to keep the LEDs as close as possible without stressing the top leaves so plants grow fast in the vegetative stage. Keeping lights close also maximizes yields in the flowering stage. However, I want to ensure top buds and sugar leaves don’t get burnt/crispy from the LEDs being too close, so I’m paying close attention to the tops of plants.

Comments from readers

  • “Only wAy to know is by measuring the ppfd. I get 1000-1200 at about 16 inches using 3x 4 foot strip lights at 300 watt each of phosphor converted white led. Total 900 watts from the wall. At 24 inches I get about 400-500 ppfd and that’s my distance in veg. Could push them a little closer but going above 1400-1500 ppfd usually needs supplemented CO2.” ~phobicbudz
  • “I’m actually battling this very thing. My girls are really struggling to adjust to my new LED light.” ~jsv1027
  • “I have a 260xl from HLG with rspec. 24″ for full cycle, fixture full blast. I would only go closer if I had a par meter because started to see stress when lower👍cant go wrong with listening to the girls.” ~mycannabiscultivars
  • “👍 Ideal distance depends on age, health, temp, humidity, co2, genetics, environment of plants. A smartphone lux meter app knowing lux to ppfd ratio can help understand how much intensity is there. More info here.” ~horticulturelightinggroup
    • This response was from HLG, the manufacturer of the LED light! ~Nebula


January 11, 2020 – 315 LEC Grow Tent

The plants are loving the 315 LEC grow light ☀ They look like they’ve grown an inch since yesterday!

I currently have the light 24 inches away and I’m letting plants grow up to the light. In the past, I’ve kept the 315 LEC about 18″ away, but I try to listen to the plants and raise it if the top leaves get crispy, start turning yellow, or get bright yellow tips. In my experience, those are the first signs of light stress.

Usually, plants are resistant to light stress in the vegetative stage because they’re constantly growing and getting bigger.

It’s in the second half of the flowering stage when plants are most prone to light stress because they stop making new leaves. I try to keep leaves as healthy as possible in flowering so they last until harvest.

Leaves are important because they turn light into energy/food, which is what powers the growth of buds.

Healthy leaves also give you another advantage. In the flowering stage, leaves act as a wall of protection for your buds. Usually, light stress (and nutrient deficiencies) will discolor the fan leaves first, then the sugar leaves, and only after that does it spread to the buds. That gives you time to correct any problems before bud quality is affected.


January 11, 2020 – Light Meter Discussion

I need your advice everyone!

People have been asking about the light levels since I started growing with a Quantum Board LED.

I have a $25 lux meter, which is helpful for determining how light levels change at different points in the tent, but it’s not accurate when comparing lights with different spectra. The “lux” measurements it gives aren’t comparable from one grow light to another.

For example, in my experience a flowering cannabis plant is happy with 80,000 lux under an HPS, but can’t stand over 40,000 lux under an LEC (though they get comparable yields at those distances). To me, that says the cheap lux meter isn’t measuring all the light coming off the LEC.

I know anything less than $3000 lab equipment uses calculations based on multiple data points as opposed to measuring the total number of photons, but it seems time to upgrade to something better than what I have.

I don’t plan to use the light meter instead of just looking at the plants, but I want to take accurate measurements so I can offer as much information as possible about what’s going on in my tent.

The Apogee MQ-500 listed here seems to be one of the best-rated light meters under $1000. There’s also a Hydrofarm light meter for $165 but it’s very poorly rated on Amazon.

Who else uses a light meter? What model did you get? What measurements have you found to be optimal? It’s quite an investment so I’m trying to decide whether this purchase would be worth it 🤔

Comments from readers

  • “I think most people trying to do the same use the apogee. It won’t give you any readings above 660 last I checked tho.” ~mihydroworks
  • “That’s the one I have. HIghly recommend.” ~mvivrett
  • “Great content, as usual..!! I own a Hydrofarm Quantum PAR Meter from Amazon for 125€ I think. Loads of bad reviews, but couldn’t afford anything more expensive. She won’t work unless charging, ha, but works nonetheless. Although I’ve not tested her actual readings against an industry hotshot. I’ve an oversized driver with dimmer, so I hang my lights as high as poss, about 140cm from floor, and need to measure from there…” ~uncleandysbeard
  • “Lux is okay for comparison only when spectrum of light is similar.” ~horticulturelightinggroup


January 15, 2020

I have a challenge with my side-by-side experiment. Check out these pictures from my two different grow tents.  I’m not sure how well you can tell from the pictures but the LEC plants are a few inches taller.

Top is the HLG 300 Quantum Board LED. Bottom is the 315 LEC grow light.

That kind of makes sense for a few reasons. It’s been chilly at night and the QB fixture doesn’t put off a lot of heat. As a result, it’s been 70-76F in the QB tent for the last week, but 73-80F in the LEC tent. Plants typically grow faster vegetatively when it’s warm, and LEDs in particular often perform better when it’s warmer. (I just can’t bring myself to buy a space heater for a grow room in San Diego).

The other thing that comes to mind is that the QB is optimized for flowering (it’s an R-spec model) while the LEC is more of an all-around light. Personally, I don’t think the differences are meaningful since it’s only the vegetative stage, but this creates a challenge for the side-by-side experiment.

The LEC plants are ready to be flipped to the flowering stage (they’ve reached half the final desired height) but the QB plants need a few more inches.

My question: Should I switch both tents to 12/12 to try to keep it fair, or should I switch the LEC today and then the QB tent in a few days when the plants have reached the optimal height?

My instinct is to compromise between the two tents and flip them both at the same time.

Comments from readers

  • “I’d flip same time for side by side.” ~king_khola
  • “The 315 looks denser to me! Flip them both at the same time, I would guess the led tent will stretch more in flower but I may well be wrong 👍” ~3footgiraffe
  • “Flip both for the fairest comparison.” ~envygrower123


Flowering Stage

Tents were switched to a 12/12 light schedule on January 17.

January 18, 2020

It’s BUD TIME! Here’s an update on the LEC vs LED side-by-side grow journal on Day 1 of flowering.

 HLG 300 Quantum Board LED grow light tent

315 LEC grow light tent

I changed the timer in both grow tents to 12/12 yesterday in order to initiate the flowering stage. Buds will start forming in a week or two.

LED plants on top, 315 LEC plants on bottom

The LEC plants are 13-14″ tall and the LED plants are 10-11″ tall. I always change to 12/12 when plants are about half the final desired size and I wanted 12″, so this seems like a good compromise.

LED plants on top, 315 LEC plants on bottom

I’ve noticed that the LEC plants seem more stretchy/tall, while the LED plants seem more short and squat. I wonder if that will continue into the flowering stage or if that will change during the 3-week “flowering stretch” when plants typically double in size after they get 12/12.

The HLG 300 LED grow light is an “R-spec” model, which means it has more light is the red spectrum. It’s supposed to really shine in the flowering stage. The LEC is more of an all-around light.

Which would you prefer as far as vegetative growth on your plants? Top or bottom picture?

Comments from readers

  • “How did you keep the temps low in the LEC tent ? They both look great🙌🔥” ~__danilop
    • “It’s been unseasonably cold here. Thanks! 🙏” ~Nebula Haze
  • “Why you let them so small are they gonna stretch a lot? You have a lot of room in the vertical dimension to take advantage of.” ~nikkyepicseeds
    • “I want plants to be about 2 feet tall at the end. Why? I have a 6 foot tent. LEC takes 1 foot of height for the fixture, then needs 2 feet to the plants. That’s 3 feet of height taken. The pots are just under a foot tall. That’s 4 feet now. That leaves room for plants that are about 2 feet tall in total. Since plants about double in size after switching to 12/12, I wanted to switch when they’re about 1 foot tall. You run out of height fast in a grow tent when you have grow lights that need to be kept so far away from the plants. Lights being too close can cause burning and light stress. I want buds to look pristine until harvest without brown or crispiness 🙂 If you look in the pictures, I don’t have a whole lot of room to move the lights up, but they’re already a good distance to the plants 🙂 Neither of these lights would be able to reach further down into the plants than 2 feet anyway. I’ll probably only get significant buds on the top foot or so.” ~Nebula Haze
  • “Just got some serious light stress and foxtails from switching to the HLG300 from two 100’s. This thing is strong! Can’t wait to hear how you dial yours in.” ~hateyerguts


January 20, 2020

More than just a pretty picture! Although these plants are happy and green, one leaf is displeased.

Can you spot the unhappy leaf?

What’s causing that symptom? Scroll down for the answer… I’m a little worried you might somehow spot something I didn’t 😂

Answer: Light stress. I’m referring to the leaf in the upper left with the edges of its leaves turned up. The outside of the leaf looks almost spikey.

This can happen in heat or when plants are experiencing water stress. However, indoors it’s often the result of high light levels. It’s easy to keep grow lights too close.

In this case, the Durban Poison is about 24″ from a 315 LEC. However, all the other plants in the tent don’t show any signs of stress at all. The Durban Poison clone in my Quantum Board LED grow tent is doing the same thing at 26″ from the LED. I guess this particular cultivar of Durban Poison is sensitive to light.

Since all the other plants seem joyful, and the two Durban Plants are otherwise green and healthy, I’m not going to change anything. I’ll just keep an eye on the Durban Poison plants for more serious signs of stress like yellowing, spots, or other discoloration.

What plants do you have growing right now? Have you ever had a particular strain or plant react differently from all the rest?

Comments from readers

  • “You’d think an African strain would be used to high heat & light.” ~doubledogged
  • “I see it on left side near middle 😜” ~mw_supreme_green
  • “What a sick background for a cell phone” ~that.guy09
  • “The one towards the left that had its edges curling up? 😅” ~dankcanopy
  • “I noticed that as well. At first was doubting myself then realized I know more than I think 🙌” ~hunta_mccloonz

January 21, 2020

Try to avoid letting leaves lay on top of each other. Leaves are constantly giving off water vapor and the wet spots they make from touching can attract white powdery mildew. Seeing lots of wet spots can be a sign your plants are too leafy overall.

When you see wet spots between leaves, either tuck one the leaves away or remove one. Let leaves breathe!


January 24, 2020

LEDs vs LECs 💡 Grow journal update!

LEDs on top, LEC on bottom

LEDs are about 28″ away

315 LEC/CMH is about 24″ away

It’s been 8 days since they started receiving a 12/12 light schedule to initiate flowering. Stems are stretching and every plant is showing pistils.

Yay! Soon buds will be forming!

The LEC plants are taller, but also stretchier. They have long stems between each node. The LED plants have tighter node spacing and the canopy is generally more even.

So far I think the tents are about neck and neck. When I first put the plants in the tents, the LED plants seemed stressed, while the LEC plants adjusted to the light much more quickly. At first, it seemed like the LEC tent was ahead. However, the LED plants have caught their stride and are growing visibly faster. They’re tied now, as far as I can tell.

I was going to defoliate both tents heavily, but I feel like there’s a lot of choice that goes into defoliation. I want to keep as many aspects exactly the same as I can between the tents. I decided that I’ll only be removing leaves that are A.) covering bud sites and can’t be tucked (because buds that don’t get light don’t fatten), or B.) any leaves laying on top of each other forming wet spots (to prevent mold). I think those simple rules help prevent me from influencing the results in any way.

What do you think? I value your input because I’m doing this experiment for you!

Comments from readers

  • “Defoliation needed. I went way too long and lost good bud potential because I thought I couldn’t defoliate in any stage of flower. 👏👏🏾 I’m so glad I can learn from awesome people on the community like you. Keep up the awesome work.” ~tattoogen
  • “I think you should defoliate! Follow your growers intuition, I also avoid taking off budsites unless at very bottom of plant.” ~mycannabiscultivars
  • “Normally, defoliate. But for the sake of the experiment, avoid pruning to not affect the results.” ~growingismypassion18

January 25, 2020

I always try to share problems with my plants, because even the best growers get a few bad leaves here and there! I turned up the contrast so the symptoms are easier to see.

Here’s a closeup of symptoms on a few top branches of the Pacific Punch clone in the LED tent.

That Pacific Punch plant is top right.

Exact same symptoms on the Pacific Punch clone in my LEC/CMH tent!

Closeup of the Pacific Punch in LEC tent. Affected leaves in the middle.

LEC/CMH tent. Pacific Punch is top right.

What’s causing the discoloration and curling?

Since it’s affecting both Pacific Punch clones exactly the same, that makes me think it has nothing to do with the lights.

My theories:

  1. Bad pH at the roots. I always pH my water, but I’ll check the runoff of both plants after the next watering to make sure pH is staying between 5.5-6.5 for coco.
  2. It’s been warm lately so I just turned the exhaust fan from half power to full power the day before these symptoms appeared. So perhaps that somehow stressed these plants.
  3. I used up the last of my Cal-Mag with the last watering. A little part of me wonders if I shouldn’t have used the Cal-Mag at the very bottom of the bottle. Maybe it was super concentrated or had some other problem.
  4. I may be overwatering the plants a little. Watering too much or too often can cause odd symptoms.


If it’s the exhaust fan, they should get used to it. I’ve got a fresh bottle of Cal-Mag, and I’ll be checking the pH of the runoff water next time I water. I’ll also give a little less water for a few days. I feel pretty certain this combo should stop the symptoms from spreading.

Comment from reader

  • “I just had a very similar incident in which I used the very bottom of what was a gallon on cal mag on 3 plants then opened a new bottle to finish out the garden. Those 3 plants were 3 shades of green with a few brown spots in 2 days. All the new growth is happy green or purple being an Anvil Auto but damage is done” ~green_thumb_grower_081


January 29, 2020

Day 13 since 12/12 and all twelve plants are flowering and stretching!

HLG 300 Quantum Board LED grow tent

The plants under the HLG 300 LEDs are a bit shorter, but have less space between sets of leaves. More manageable. I’m very pleased with the canopy and how they look in general. I haven’t really had to do anything to shape them since I put the plants in the tent. They’ve been growing closer to the light without any signs of stress, so I haven’t been moving the fixture up. Currently about 24″ away and thriving.

The LED plants also seem greener, happier, and faster-growing than the plants I grew under ViparSpectra LEDs. The HLG 300 actually only used 260w when I measured the electricity usage with a kilowatt meter, which means the HLG 300 fixture uses less wattage than the others, too. I’m so excited to find out what these LEDs can do in the flowering stage!

315 LEC grow tent

The plants under the 315 LEC/CMH are taller but stretchier, with longer amounts of stem between sets of leaves. That’s okay as long as those long branches turn into long buds, but not ideal.

So far the only plant getting really tall is the Durban Poison in the back left of the LEC tent. I know from experience that spot is good for tall plants because it gets light from the side of the bulb but won’t run into the light itself. I’m just going to let it be for now.

  • “Nice! A friend of mine is on his first run using HLG lights and is loving the results so far! I look forward to seeing your results. I may be in need of a lighting upgrade 😎” ~electric.gardener
  • “Do you think if you had the lights a little closer you would’ve got tighter nodes?” ~automaticgreenthumb_
    • “It’s possible, but I didn’t want to keep it closer because a few leaves were showing signs of light stress.” ~Nebula Haze


February 4, 2020

Bud development check-in! Week 2.5 of flowering.

Buds from the HLG 300 LED grow tent. The Lemon Lime plant (top middle) seems to be growing pink or purple buds.

The LED Tent (plants are in the same order for easy comparison)

I’m SO pleased with the LED tent. The buds are stacking, the canopy is even, the plants look happy. LEDs are currently 20″ away and leaves aren’t showing signs of stress. I still have plenty of room to raise the light up if needed. It’s stinky. The Ocean Fruit plant in here seriously smells like candy. Buds are starting to get sparkle.

Buds in the 315 LEC grow light tent

Bud size seems about the same between the clones in both tents, except the Durban Poison, which do seem bigger under the LECs. Buds look slightly more sparkly in this tent, but don’t have a strong smell yet.

315 LEC grow tent

The 315 LEC grow tent is much less orderly. Plants are taller and stretchier. I normally would have set this one on 12/12 sooner, but the LED plants were too short so I compromised. I wanted to switch when they were 12″ tall. LEDs got switched at 10-11″, the LEC plants were switched at 13-14″ tall. It seemed fair to do it halfway for the purposes of the experiment.

As a result, the LEC plants are getting too tall. I only have another 5 inches or so to move the light up and plants are 18-20″ away (about as close as they should get). This tent is going to be a great example of dealing with too-tall plants. Luckily I have experience wrangling wild plants! I think it’ll be okay.

As far as user experience, the LED is winning in my mind 🥇 I love that the LED has the ability to turn lights on and off instantly. The LEC must wait 10 minutes after being turned off to turn on again. That’s a pain because I turn off the lights every time I check on my plants (grow lights bother my eyes). I like the thin LED profile and how orderly the LED plants are growing.

I’m actually surprised how much I like this LED light. The plants seemed stressed and shocked at first but now they’re loving it!

Comments from readers

  • “You ever try an experiment with having many plants vs few with the same canopy area. (5×5 2 plants vs 12) would having more plants make better quality buds? In terms of density and what ever else. I know the yield should be identical. But I’m wondering for the amount top quality buds. Thanks in advance for weighing in.” ~taktalok
    • “I’ve found growing a bigger number of plants usually produces a bit more yield (“Sea of Green” technique) for the same amount of space, but buds are generally smaller and less dense. Especially if you let tons of buds grow as opposed to training the plant to have just a few main buds. You get the most density when no nuggets are allowed anywhere. The most consistently dense buds I’ve grown have been when “manifolding” plants to have 8 main colas, lollipopping them right at the start of flowering, defoliating week 1 and 3. It works best when growing just 1-2 plants in my 2×4 space. But I’ve found I get better overall yields with multiple plants and more buds. I also get more strain choice. So it’s kind of a compromise between limiting the number of buds for density, but leaving enough you get as much bud as you want. The genetics make a huge difference to density. You can get buds of very different densities out of the same tent, and the only difference is strain 🙂” ~NebulaHaze

February 5, 2020

When it comes to bud size and number of bud sites, there’s a definite winner in both my grow tents so far… Durban Poison by Dutch Passion!

Plants started 12/12 less than 3 weeks ago andthe  top buds on the Durban Poison clones are already as thick as my thumbs! Most of the other plants still have mostly wisps of white hairs.

Here is the Durban Poison growing under an HLG 300 Quantum Board LED grow light

This plant is its clone growing under a 315 LEC grow light

These two plants epitomize the differences between the two tents so far. The LED plants are growing super orderly, wide, with great node spacing. I haven’t had to do anything to any of the plants in the LED tent since I put them in on New Years.

On the other hand, the LEC plants are growing wild, stretchy, and leafy. The stems are long and willowy. I’m supporting the tall branches of the Durban Poison with plant yo-yos already. The colas were leaning towards the light and I knew they’d eventually fall without support. I decided to hold them exactly where I want them. However, despite the wild growth, the buds appear to be bigger on the LEC plants so far.

I’ve discussed in the past how European strains tend to grow vigorously with huge yields. American strains often grow a bit slower with smaller yields, but buds come out smellier and sparklier (better bag appeal, Americans want impressive brag-worthy buds!). Of all the 6 strains I’m growing, only the Durban Poison is from a European breeder (Dutch Passion), and it’s extremely noticeable the differences in vigor and bud size/stacking compared to the American strains. With 12 plants in total, I’ll harvest plenty of buds so I’m not super worried about yields. I prefer better bud quality despite lower yields. That being said, Durban Poison is one of my favorite strains to smoke…

February 7, 2020

LEDs vs LECs 💡 Who will win? Honestly, from the look of these tents so far, I think both will be winners!

It’s been exactly 3 weeks since I initiated the flowering stage with a 12/12 light schedule. The LEC seems to be winning for bud size (so far) but the LED plants are flowering hard. They could be catching up!

I took pictures in the dark with a flash so you can really see the bud size and placement. (LEDs on Top, LECs on Bottom)

I noticed from the pictures that some of the leaves look a bit pale. I’ll be raising the nutrient levels.

The LED plants have grown to about 18″ away, which is pretty close for an HLG 300. The front-right plant (Ocean Fruit by Square One Genetics) under the LEDs is pale on top but darker lower down. That’s a sign the LEDs are too close. I’m going to move the LEDs up to 24″ away.

Once I give the plants higher nutrients and those leaves darken to the proper color, I may move the LEDs down again. Closer lights = bigger buds as long as plants are healthy and the environment is right.

The LEC plants stretched a lot since 12/12. They’re about 2.5x the size they were 3 weeks ago. I just moved the LEC grow light to the top of the tent, and it’s about 18-20″ away from the tallest colas. They don’t show any signs of light stress yet.

Normally I would supercrop (bend) the problematic colas to the right distance, but I don’t want to potentially affect the results of this experiment.

Comments from readers

  • “Keep em and bend the tallest ones your worried about.” ~errrban_gardner
  • “I’ve noticed LEC buds get bigger but they are a lot fluffier and not near as dense as the white light LEDs produce.” ~24_kt_green
  • “Well really bending them isn’t affecting the lec/led comparison.If anything I reckon it’s stabilising the experiment.of they are that close then you should bend em” ~paulyella
  • “Let em roll….Don’t stress em” ~doubledogged
  • “Just want to say a big thank you to you and Sirius, I have been referring to the Growweedeasy.com website since 2013. I teach abroad and have been residing in highly restrictive regions of the world, when I decided to exercise my God given rights to be heathy without pharma drugs, I learned everything I needed from that highly informative site. Thank you for the time and dedication to quality, God bless you both. Peace and prosperity 🙌🏾” ~ptyplug420


February 9, 2020

Horrible news today… 📰

When I checked on the plants today I see that both Durban Poison plants have hermed on me.

The word “herm” is short for hermaphrodite and means the plant is growing both male and female flowers.

Sometimes you see full pollen sacs as you’d see on a male plant, but sometimes you see pale (often yellow) “bananas” appear among the beautiful buds 🍌 If you look closely at the pictures of buds you can see they’re sprouting bananas everywhere.

What’s the big deal? These release pollen, which pollinates buds and makes them produce seeds. You can see brown pistils/hairs in some pictures. Those are attached to calyxes that have already been pollinated.

These Durban Poison plants by Dutch Passion were clones of each other and both tents have been receiving great conditions, so I’m chalking this up to genetics. Every other plant has perfect buds.

They’re currently quarantined and both plants are getting tossed tonight under cover of darkness. I’ve been luckier than most. In 12 years of growing, I’ve never had a plant herm like this before. It was bound to happen eventually. I saw some odd yellowing coloring on a bud and I’m glad I knew what it was! I hope I caught the herms soon enough that they haven’t seeded other plants in the tents.

Disappointing for sure. I was singing praises for these Durban Poison plants a few days ago. They both looked like they were going to yield 2-3x more than any other plant.

But c’est la vie. In the words of Marcus Aurelius: “You have power over your mind – not outside events. Realize this, and you will find strength.” 💪 There’s no point in worrying about what can’t be changed!

Who else has had to throw away a gorgeous plant due to herming? Do you think it was caused by genetics or something else?

Comments by readers

  • “😥. This happened to me on my first grow. I believe it was genetics I used a couple bag seeds. Along with tester seeds from a breeder. I grew them out I didn’t have the strength to kill them lol. The finished bud was gross so I soaked in in Everclear.” ~weiler_bull
  • “Currently had a beautiful Red Eye OG in quarantine due to hermie soo sad.” ~jacobid82
  • “Oh nooo!!! This is always a fear of mine as cutting down such beauties is hard on my soul lol.” ~smitten.kitten.grows

February 12, 2020

Starting to see some noticeable differences between the buds! They’ve been getting 12/12 since Jan 17, or about 3.5 weeks.

The top pictures show the buds growing under an HLG 300 LED panel. The bottom pictures shows a clone of the same plant growing under a 315 LEC grow light.

Pacific Punch

Zweet Inzanity

Mandarin Cookies

Lemon Lime

Ocean Fruit

LED tent

LEC tent

Here’s what I’ve noticed so far. Some LED buds are bigger, some LEC buds are bigger. It’s like some plants prefer one light or the other. I think some LEC buds look more sparkly, but the LED plants smell stronger so far.

Comments from a reader

  • “Definitely a difference in frost” ~tanyaknjp

February 14, 2020

Today I’m testing light levels with my new Apogee MQ-500 light meter.

1st video is the HLG 300 Quantum Board LED grow light in a 2’x4’x6′ grow tent. I have it about 20″ away from the tops of plants. It measures about 700 in the middle on the meter (up to 800 on a few of the tall colas), and the very sides get as low as 450.

2nd video is a 315 LEC grow light in the same size tent. I have it about 18″ away from the tops of plants. It measures about 550 around the middle (there’s a handful of tall colas getting up to 750), and down to 250 at the very edges.

The Apogee MQ-500 measures in µmol m^-2 s^-1 (micromol per square meter per second). Basically, just pay attention to how the numbers change in different parts of the tent, with high numbers meaning more light.

The LED numbers are higher across the board, and more evenly spread through the tent, even though the LED is designed for a 3’x3′ space, HLG has a new version of this exact LED meant for a 2’x4′ space (on my wish list!), and I imagine that light would be even more well distributed.

The LECs don’t fare well on this particular test, in part because it has poor coverage on the sides. It is also designed for a 3’x3′ space, not a 2’x4′, and it really struggles to read the edges of the tent.

Comments from readers

  • “Numbers r different but the flower almost the same… Thx for the readings👍” ~keepemgreenjgood
  • “Gettin nerdy I love it! Beautiful 🤘” ~craftcannamike


February 16, 2020

Take a video tour of the LED grow tent!

We’re in week 4 of flowering (30 days since 12/12) and buds are starting to get some heft and sparkle!

Zweet Inzanity

Zweet Inzanity buds on day 30 of the flowering stage (week 4)

Mandarin Cookies

Mandarin Cookies cannabis buds on day 30 of the flowering stage (week 4)

Lemon Lime

Lemon Lime cannabis buds on day 30 of the flowering stage (week 4)

Ocean Fruit

Ocean Fruit cannabis buds on day 30 of the flowering stage (week 4)

Pacific Punch

Pacific Punch marijuana buds on day 30 of the flowering stage (week 4)

The plants have really hit their stride and buds seem bigger every day! 💪I’m surprised how deep the light seems to reach into the plant because the buds are more stacked than I normally see under LEDs.

The leaves seem a bit more pale towards the top of each plant but otherwise not much evidence of light stress from the LEDs. The fixture is about 20″ away and I’m not going to raise it unless the top leaves start get crispy or discolored.

It’s a jungle in there 🌿 I’m happy with this light so far!

Comments from readers

  • “Looks like love has been in the room good grow.” ~love_smoke_cultivate

February 16, 2020

Check out these 5 plants growing under a 315 LEC grow light. Day 30 since 12/12 (in week 4 of flowering). The LEC tent looks like it snowed! So many trichomes. Check out my last post to see clones of these plants growing under LEDs.

I think the Mandarin Cookies plant has the most trichomes, but the Zweet Inzanity plant seems the highest yielding so far.

Zweet Inzanity

Zweet Inzanity bud - Day 30 since 12/12 (in week 4 of flowering)

Mandarin Cookies

Day 30 (week 4) flowering stage - Mandarin Cookies bud

Lemon Lime

Lemon Lime marijuana strain - Day 30 of the flowering stage - grown under 315 LEC grow light (CMH)

Ocean Fruit

Ocean Fruit marijuana strain - Day 30 of the flowering stage - grown under 315 LEC grow light (CMH)

Pacific Punch

Pacific Punch marijuana strain - Day 30 of the flowering stage - grown under 315 LEC grow light (CMH)

Comments from readers

  • “Yes the mandarin cookies tend to give a lower than average yield when compared to plants in the same environment, but quality in terms of terpenes and trichome production is top notch, hence the term boutique flowers. You can also get some really pretty colors from her when using the right lights which you are . Colors Usually only starts to kick in at about week 6 though. Best of luck ✌️✌️✌️” ~somerset_terps
  • “I’ve read once that the abundance of trichomes on the buds doesn’t always translate to high potency, meaning some strains could have a lot of them and still be lower in the cannabinoid content – which is supposed to be a genetic trait that you can either enhance or somehow suppress depending on the growing conditions. Has anyone experienced that?” ~prensadoplantado
    • “Yes, that’s been my experience too. Sometimes the strongest buds aren’t that sparkly, but it’s rare to get a really sparkly bud that feels totally weak unless it’s a CBD strain. I think it’s because breeding goes into trichome production, so if there are lots of trichomes, likely the plants were carefully bred. But it’s only been the last decade in America that breeders really starting going for trichome production. Potent strains from other parts of the world usually aren’t as covered in glitter as American strains.” ~Nebula Haze
  • “What’s your humidity and temp in the tent?” ~jaclyn.phoenix
    • “Humidity is 40-50% RH and temperature is between 70-80F day and night” ~Nebula Haze
  • “Plants look great!! How much water are u giving” ~canweplayhockeyplease
    • “I’ve been giving about 2-3 gallons per 5 plants every 2 days. I go based on how heavy the pots are.” ~Nebula Haze
  • “Ethos Mandarin Cookies looking bomb . On my immediate radar. Any thoughts 👍” ~vancitygrower
    • “The Manderin Cookies by Ethos doesn’t seem as high yielding as the others (based on bud size), but the sparkle in both the LED and LEC tents is out of this world!” ~Nebula Haze
    • Post Harvest Update by Nebula: “Now That I’ve been smoking the Mandarin Cookies for a little while I definitely have some thoughts. First, it tested highest in THC of all the plants I grew in this run. It was relatively low yielding but smoking the buds is amazing. The problem is the smell of the cured buds is absolutely terrible and insanely strong. I know growers strive for terpenes, but we live in a condo and you can’t really open the jar without the smell escaping the front door. And it’s not skunky or sweet or pleasant in any way. It’s an earthy barbaric rank smell. It smells like a warning from nature. I think it’s a great strain but I feel like the name “Mandarin Cookies” is a little misleading :)” ~Nebula Haze
  • “It might be trouble if trichomes appear too soon… That is what some growers say. CMH brings them too early and buds don’t finish so good and large. But also, some people seem to know what to do with them.” ~jarmovoutilainen


February 21, 2020

LEDs vs LECs grow journal update!

1st picture is the tent with the HLG 300 Quantum Board LED grow light.

2nd picture has a 315 LEC grow light.

Both tents are on day 36 of flowering. These strains need a total of 70-80 days before they’re ready to harvest, so we’re about halfway through the flowering stage!

The plants look a little dark to me, and one plant in the LED tent is thinking about nutrient burn so I’m going to pull the nutrients back about 50 PPM (just add some extra plain water to my normal mix) and see how they react. Dark leaves usually mean the plant is getting lots of Nitrogen, which can suppress bud development. I want them to stay nice and green until flush time, but a little paler.

There are major differences between the two tents now. The buds on the edges of the LED tent are significantly bigger than the buds near the edges of the LEC tent, especially the Zweet Inzanity plant on the left.

That makes sense considering the Apogee MQ-500 light meter showed the LED tent had a pretty even light spread, while the LECs had poor coverage on the edges. The buds in the middle are bigger in the LEC tent, especially the Mandarin Cookies in front center.

I think overall the LED buds are thicker, but the LEC buds are longer.


February 21, 2020

The Mandarin Cookies plant in my LEC tent is definitely the sparkle monster of the garden. No other strain comes even close to this trichome coverage.

mandarin cookies trichome-sparkle-monster

Currently, 36 days since 12/12 was initiated, so this plant is only about halfway through the flowering stage.

Do extra trichomes mean increased THC?

Not necessarily.

Some high-CBD/low-THC strains get just as sparkly, but don’t have strong perceived “potency” because the THC has been bred out. You can’t look at a plant and know how potent it will be. That being said, this level of trichome coverage usually takes dedicated breeding over generations. Therefore, it’s almost always a good sign to see lots of trichomes because it means you’re growing a strain that was developed by caring breeders.

The type of grow light also has an effect on trichome production. I’m growing a clone of this plant under LEDs and the buds are still extremely sparkly, but not like this.


February 29, 2020

See this little nug at the bottom of the plant falling over? This whole branch should have been removed before the plant started making flowers.

Normally I like to “lollipop” plants right as they start flowering, which means to remove all growth below a certain point on the plant 🍭 Lollipopping creates bare stems on bottom and all the “good stuff” is concentrated on top close to the lights.

That would have prevented tiny little buds from forming at the bottom of the plant, which are falling over and probably have to go in the trim pile after harvest. Lollipopping also would help the main top buds get fatter.

Check out this picture to see what I mean. The front right plant would have benefited the most (that’s where this falling nug is located) but I think lollipopping would have helped them all.

I don’t want little buds going all the way down to the base. Those bottom nugs are barely getting light and will never thicken properly. The LEDs only penetrate so far into the plant.

I didn’t lollipop because of the side-by-side experiment and I didn’t want to introduce extra variables. I knew lollipopping would be a potential variable because I’d have to choose which branches to take or leave.

I’ve tried to stay “hands off” as much as possible this entire grow, and it really makes me appreciate how much easier the grow process is when you using plant training, defoliation, and other manipulation to make plants grow in a more favorable manner indoors.

But never again! I’m going to standardize lollipopping in future tests because this is ridiculous. All these little nugs stealing energy from my main colas!

Comments from readers

  • “I lollypop hard and grow 4 branch symmetrical plants. I get zero “larf”. Been doing it for years with some bonsai techniques.” ~trailfather666
  • “I lollipop, keep them squat by topping a couple times and defoliate just before that switch to flower and then again at about the third week of flower, just after the stretch period. I Get great results using these methods. Done my own side by sides and the defoliated plants are always better yielders, especially with some hst and lst. Defoliation helps with so many other issues as well that can happen while growing indoors. it’s really a no brainer for me. Outdoors I sort of let the plants do their thing but indoors I’m all about keeping things nice, tidy and efficient. I learned about mainlining on your website a while back and every now and again I’ll mainline some just because it’s also a great technique, I usually only do a mainline from seed….maybe for my outdoor run from seed this year….” ~phobicbudz
  • “Well, that is bag appeal vs. terp profile. Sometimes the larf is actually stronger and more terpy than the main colas. Besides, small pieces are easier to smoke or vape than larger ones anyway. So in reality, all it is is bag appeal. If you aren’t selling, and we are grinding before rolling or loading into our utensils, then why should we care if we have larfy buds?” ~doctor_philgood

March 3, 2020

Starting to see purple 💜 on the top leaves of my plants under HLG300 LED grow lights. I’m not seeing any purple on the clones of these plants of my LEC tent, so it seems it’s the LEDs in particular bringing out the colors. (Learn more about purple plants)

In the past, I’ve noticed that plants under LEDs are more likely to turn purple, though only if their genetics allow. For example, the Zweet Inzanity plant all the way on the left is turning pale green (and will eventually turn yellow) instead of purple. That plant seems to be a heavy feeder and will be getting a slightly higher dose of nutrients next watering.

The ones turning purple are Ocean Fruit, Pacific Punch, and Mandarin Cookies. What a tasty bunch to turn purple. The only plant still totally green is the Lemon Lime plant in back middle (Palm Beach Sour Apple x 87 Limepop). As far as purpling from LEDs, it usually doesn’t affect the buds all the way down at first. It starts with the parts at the top of the plant getting strong, direct light, and slowly climbs down over time. Colors really pop as soon as you stop giving nutrients during the flush.

It’s pretty cool to open the tent and see tints of purple appearing everywhere!

Cool temperatures (or big temperature swings between day and night) are more likely to induce purpling. The tents got down to 65F the last 3 nights and I think that may have helped trigger the color change.

These plants have a few weeks left to go (still seeing lots of clear trichomes and zero amber/yellow trichomes) so I’m sure the purpling will continue. It looks so cool. I wonder how far into the plant it will reach by harvest.

Comments by readers

  • “Very nice plants. I have one of these lights and I can’t say one bad thing about it. I love it.” ~m_c.l

March 3, 2020

I feel the LED tent is taking a lead for bud weight. The middle LEC buds (directly under the light) are bigger, and all the LEC buds are longer, but the LEDs seem to be winning for bud thickness overall, especially on the side plants. That seems like it will make the difference.

Top is LEDs, Bottom is LECs

HLG 300 Quantum Board LED grow light on top, 315 CMH grow light on bottom - Cannabis grow journal

Both LEDs and LECs are about 18″ away from the plants.

The LED tent is starting to get purple-tinted on top, while the LEC tent is still totally green. LEC buds are significantly more sparkly, but most of that is the trichomes taking over the leaves. That’s going to be great for making hash out of the trim, but I’m not sure how much of an effect it will have on buds.

These plants are in week 7 from 12/12. I’m guessing the two right plants in both tents will be ready to harvest in 1.5-2.5 weeks. Their hairs have mostly darkened and curled in, but under a magnifier the trichomes still have lots of clears left. The other plants will probably take a few more weeks longer since their hairs are all still mostly white.

If I light the buds really well and keep my Galaxy phone ultra still and zoomed in, I can usually see trichome color with the built-in camera. I try to go for mostly white with few clears left. However, I’ve had the best results using a USB magnifier connected to my phone. Now that’s clarity.

But luckily even if just going by bud appearance, there’s about a two week window to harvest. A little early or late doesn’t make a huuuge difference so don’t stress too much 🙂

Comments from readers

  • “How do you check the temperature in the plant area? I have a thermometer on the top of the tent, but if I place the thermometer next to plants it gets hotter and hotter every second. How do I get the proper temp under my lamp?” ~tomdext3r
    • I started using the ETHMEAS Digital Thermometer and Hygrometer. I keep it on top of the tent but it has a probe that can be hung inside the tent. I hang mine from the side so it’s at about plant height, but not in direct light. I’ve checked it against other thermometers and it seems to be accurate and has held up to the grow lights so far.” ~Nebula Haze

March 5, 2020 

Day 48 of 12/12. Compare the differences between buds. Since these clones have been treated identically, any differences are likely from the grow lights.

(Top pictures are LEDs, bottom pictures are LECs)

Zweet Inzanity

LEDs vs CMH grow lights - Zweet Inzanity - Top LEDs, Bottom CMH

Pacific Punch

LEDs vs CMH grow lights Grow Journal - Pacific Punch - Top LEDs, Bottom CMH

Ocean Fruit

LEDs vs CMH grow lights Grow Journal - Ocean Fruit - Top LEDs, Bottom CMH

Palm Beach Sour Apple x 87 Limepop (Lemon Lime series)

LEDs vs CMH grow lights Grow Journal - Lemon Lime - Top LEDs, Bottom CMH

Mandarin Cookies

LEDs vs CMH grow lights Grow Journal - Mandarin Cookies - Top LEDs, Bottom CMH

Full HLG 300 LED grow tent – Day 48 of 12/12

Cannabis grow journal with Quantum Board vs CMH - HLG 300 LED grow tent - Day 48 of 12/12

Several plants are turning purple from the top down in the LED tent. Many buds seem bigger in this tent (though the Mandarin Cookies plant in front middle has significantly bigger buds under the LECs). I’ve been pleasantly surprised by the HLG 300. It uses about 20% less electricity than the LEC, produces less heat, and the buds are rock hard. The Ocean Fruit and Pacific Punch buds may be the hardest/most dense buds I’ve ever grown.

Full 315 LEC grow tent – Day 48 of 12/12

Cannabis grow journal with Quantum Board vs CMH - 315 LEC grow tent - Day 48 of 12/12

All buds are covered in trichomes (thanks to extra-sparkly genetics) but the LEC tent looks like it snowed. Every sugar leaf is covered in trichomes, and lots of the fan leaves are, too. This is going to be some epic trim!

Both light fixtures are 18″ from tops of plants.

For the fairest comparison, I’ve avoided messing with the plants after they went into the tents (besides giving water). I don’t want to unintentionally affect the results by introducing new variables, so I’ve abstained from my normal plant training tactics like lollipopping and pruning. It’s a little wild as a result, but this ensures grower skill does factor into the outcome. Anyone could copy this grow and get the same results!

Some buds look ready, but trichomes say they need more time. I plan to harvest after most trichomes are cloudy with a few ambers.

The smell is overpowering! It’s so strong I can’t tell which tent smells more.

Comments from readers

  • “Do you run that light at 100% power all the way through?” ~310grow
    • “Yes it’s been at full power since the beginning 🙂” ~Nebula Haze

March 6, 2020

When to harvest cannabis for the highest potency? There are many methods but looking at the glandular stalked trichomes (glitter on buds) under a magnifier may be the most accurate. The color of the heads gives you clues to the potency.

Clear = Not yet at full THC. “Speedy” effects.

White/milky = Highest level of THC, and greatest level of psychoactive effects.

Amber/yellow = Some of the THC has turned into CBN (not CBD, which is based on strain and develops alongside THC). CBN is a little less psychoactive but gives more of a “couchlock” body effect as opposed to mostly affecting your thoughts.

These 3 pictures are the Ocean Fruit plant in the 315 LEC tent. This is the closest plant to harvest I have right now according to the trichomes.

The next three pictures show a clone of the same plant from the HLG300 LED tent. Pretty similar to the other.

Most other plants have nearly all clear trichomes but these ones actually are thinking about harvest time. There are few clears left, and an amber trichome here and there. Some people might even start flushing now if they didn’t want much of a body effect.

I’ll probably stop giving nutrients to the Ocean Fruit clones (start flushing) soon. I’d like to flush for a week in total since these are in coco. I want to wait until there are no clears to start the flush. They look close to each other as far as maturity so I plan to flush and harvest them on the same schedule.

At only 49 days in the flowering stage, this may be the fastest flowering plant I’ve grown!

All pictures were taken through a Wesley’s jewelers loupe with my Galaxy phone zoomed in. I’m actually pretty impressed with how effective that is! I didn’t even have to take out my USB microscope.

When do you harvest?

Comments from readers

  • “I chop after I see a few ambers” ~normal.man2
  • “The ocean fruit and pacific punch both finished pretty fast for me. I use a usb “microscope” (cheap zoomed in digital camera basically) and check the trichs when they look close. I wait for mostly cloudy and some Amber to start showing up and call it good. They continue to cloud up during dry/cure” ~o_hai_nathaniel
  • “I like to harvest with between 10% to 20% amber, some cbn is always my goal for medicinal purposes✌️” ~thebudgetgrower
  • “I cut when they milky !!! Love this effect !!! I check twice a day with microscope~” ~vegetoo420
  • “I use the lighted handheld Carson 60-120x microscope from Amazon $15.00. I usually go with between 100% milky to about 30% amber at the most.” ~watching420grow
  • “I always chop at about 20 to 25% Amber to milky🤘 you’re going to have a nice Frosty Harvest👏” ~craftcannamike

March 7, 2020

Wow the LED tent is looking and smelling great!

The plants are 50 days from when I initiated the flowering stage with a 12/12 light schedule.

It’s crazy how big a difference the strain makes on bud size!

The plant with the biggest buds (Zweet Inzanity all the way on the left) still has a lot of white hairs and probably needs the most time until harvest. Maybe another few weeks. That means those buds will be fattening the whole time.

On the flip side, the Ocean Fruit and Pacific Punch on the right are actually closer to the LEDs (and getting lots of light at 900 PAR), yet buds are much smaller. Those plants are very close to harvest. They’ve got maybe another week. I’ve started flushing so their buds are not going to get much bigger.

I think this demonstrates how some strains get smaller yields than others, regardless of what you do.

Long-flowering strains often get the best yields. A few extra weeks in the flowering stage makes a huge difference. Yet plants can be ready to harvest at the same time, and some strains simply fatten more than others even when given identical growing conditions.

But check out this picture of the Pacific Punch plant.

The buds are probably the smallest in the tent but look gorgeous. They’re extremely dense, sparkly, turning purple, and just look top-shelf. Maybe the smaller yields are worth it for the bud quality?

I’ll find out after harvest!


March 9, 2020

The 315 LEC grow tent looks like it got hit by a glitter bomb 🕺 It’s a disco in there!

The 315 LEC/CMH tent

The trichome coverage is the result of sparkly strains combined with the 4000k bulb on the LEC. Something about that bulb really brings out the sparkle, though in my experience buds get significantly smaller than they do under the “flowering” 3100k bulb. I’ve heard other LEC growers say to flower plants under the 3100k bulb so you get the weight and yields, then switch to the 4000k bulb for the last 2 weeks to bring out the trichome production. I may try that next time!


March 17, 2020

These tents are going to be ready to harvest soon!

Top is LEDs, Bottom is 315 LECs

Full HLG 300 LED tent

Full 315 LEC tent

The tents look pretty different! Lots of purple leaves in the LED tent, and mostly all green leaves in the LEC tent. However, the buds are about the same color between the tents (some are purple-tinged, some are the standard green). The LEC buds have more trichomes so they appear more pale, almost sorbet colored.

Pacific Punch in LED tent

Pacific Punch in LEC tent

I thought the LED tent was going to win for yields but now I’m less sure. The LEC buds have really been fattening up this last week, especially the ones directly under the grow light. I think I won’t know until after harvest.

I have the two right plants flushing (no nutrients) in each tent. I plan to harvest those this weekend. The rest of the plants need a bit more time.

They’ve been flowering for about 8 weeks (initiated 12/12 on January 17).

Comments from readers

  • “Looking solid. I am biased and I’m gonna say I prefer the led so far. Bud quality might be only slightly inferior(in crystal coating not color) but I prefer the efficiency and low temps especially cos I’m in a very hot climate and LED’s advantages benefits me most…” ~homegrownobsession
  • :I’ve always thought that my HLG was making my buds more purple.” ~eastmcg
  • “Looks like the LED tent has more uniform trichome and maybe bigger heads? While the LEC one looks to me to have strangely longer stalks?” ~king_khola
  • “Wow the LEC looks way frostier! Like an extra layer.” ~oneday_someday10



Now it’s harvest time. We made it!

March 26, 2020

Harvest day! Here are some harvest pictures from my two tents. First shows buds, then the LED and LEC tents.

LED tent

LEC Tent – I forgot to take a pic of the LEC tent until I was almost done harvesting the two right plants. Oops!

Lots of purples and pinks appeared since I started flushing.

Buds are air-drying in their tents with the temperature set to 62°F (17°C), which is as low as my AC goes. I anticipate they’ll take 7-10 days to dry.


April 21, 2020

Lab results for terpenes and cannabinoids should arrive this week and I’m waiting on the edge of my seat. I can’t wait. LEDs vs LECs! What will the differences be, if any?

Grown under a 315 LEC grow light

Grown under a HLG 300 Quantum Board LED grow light.

Here they are spliced together for easier comparison (left is LEC, right is LED).

Overall the LED buds tend to have a purple tint and the LEC buds got a sparkly sorbet finish. All buds are super sticky!

In smoke tests, I only have one thing to say… Awesome! I can’t tell the difference between the buds yet, I can only say that they’re both terrific.


Yields, Lab Results & Bud Quality

The weights and lab results are in for the LEDs vs LECs grow journal! Cannabinoids and terpenes and yields, oh my!

Quick summary:

HLG 300 LED grow tent – 260W

  • Total 9.34 oz
  • Average THC: 22.35%
  • Average Terpenes: 29.8 mg/g
  • 1.02 g/watt

315 LEC grow tent – 315W

  • Total 7.48 oz
  • Average THC: 20.58%
  • Average Terpenes: 34.9 mg/g
  • 0.67 g/watt

There was also 6.7 oz trim between both tents. I didn’t think to keep the trim separated, though I’d guess about 2/3 of the trim came from the 315 LEC tent (more on that below).

Top is the entire harvest (including trim and samples for the lab). Bottom left is LED harvest, bottom right is LEC harvest.

Here’s an excel spreadsheet so you can see a breakdown of all the data in one place:

LED Test Results [PDFs]

315 LEC Test Results [PDFs]

Note: Total THC is calculated as THC + (THC-A x 0.877) because the conversion rate of THC-A to THC is 0.877.

Overall, the LEDs won handily for weight and THC percentage. When it comes to terpenes, the LECs ended up on top. The plants had similar terpenes ratios, but the LECs averaged higher amounts overall.

Here are some bud pictures to compare between the two lights.

Ocean Fruit

LED grow light

315 LEC

Pacific Punch

LED grow light

315 LEC

Mandarin Cookies

LED grow light

315 LEC

Lemon Lime

LED grow light

315 LEC

Zweet Inzanity

LED grow light

315 LEC


Thoughts on LEC yields:

When it comes to yields, I think the LECs would have performed better with additional pruning like lollipopping and defoliation. I let the plants grow wild because I didn’t want to affect the results of the experiment, but this created tons of tiny buds at the bottom of the LEC plants, which all got thrown into the trim pile. I think the flower weights would have been more similar between the lights if the larfy bottom LEC buds were removed early, so the plants could focus more energy on top. It makes me appreciate the power of proper pruning to prevent small airy buds.

Lesson learned for my next side-by-side… Never skip plant training day! I want to keep things fair but also help each tent produce the best.

Another consideration with the LECs has to do with the bulb used. There are a few different schools of thought then it comes to LEC bulbs. Eye Hortilux recommends the 4000k colored bulb I used from seed to harvest. However, the Philips company offers two options: a 4200k LEC bulb for veg, and a 3100k color bulb for the flowering stage. In my experience, the 3100k bulb increases bud size somewhat if used in the flowering stage, but buds come out less sparkly and nice. Since the LEC lost for yields it should be noted that the yields probably would have been better if I’d flowered under the 3100k LEC bulb, though the bud quality may have been affected.

Thoughts on LED Yields

There are also some considerations about the LEDs.

One major thing working against the LEDs was the temperature. HLG recommends 78F – 84F for best performance with this light in flowering. However, it was unseasonably cold for this whole grow and the LED grow light doesn’t put off a lot of heat. Therefore the air in the LED grow tent was regularly around 68-75F. This likely reduced growth rates and yields. I bet the light would perform even better against the LECs in the summer, when the extra LEC heat will be a disadvantage.

Plus, like the LECs, these plants would have likely yielded higher if they were trained properly.

Note: HLG just came out with a version of this exact light that is ideal for a 2’x4′ grow tent. I’m switching!

The debate between LEDs vs LEC yields is not over! More testing is needed!

Now the question you’ve been waiting to know the answer to…


Which Light is the Best?

Based purely on this grow…

HLG 300 Quantum Board LED Grow Light (R-spec version)


  • Produced better yields per watt
  • Higher THC levels
  • Hardware is lighter, smaller, and easier to use
  • Seems to bring out purple leaves in some strains
  • Doesn’t bother my eyes
  • Plants thrive at higher temperatures (78-84F)
  • Plants naturally grew in an ideal bushy structure
  • You can instantly turn light on and off to check on your plants
  • Runs significantly cooler than the LEC
  • Uses less electricity


  • Buds appeared somewhat less sparkly
  • Buds had lower terpenes
  • Plants were more easily stressed
  • Plants grew slower in the vegetative stage
  • Plants don’t like low temperatures under 78F, so may not be the best grow light in a cold climate


315 LEC Grow Light (4200k bulb)


  • Better trichome production on buds and leaves
  • Higher levels of terpenes and more complex smell
  • Plants were more resistant/forgiving
  • Faster and more vigorous vegetative stage growth


  • Smaller yields per watt
  • Lower THC levels
  • Heavier/hotter/bigger hardware
  • Must wait 10 minutes after turning off to turn on again, so harder to quickly peek in on plants
  • The light really bothers my eyes (likely due to higher UV levels)
  • Plants tend to grow tall and stretchy with lots of side branches

And now… drumroll please….


The “Winner” is… 

Between these two lights, I think most home growers would be happier with the HLG 300 LED grow light. Not only did the LEDs win handily for weight and THC percentage, they also produced better yields per watt. The purple leaves were a treat. Plants naturally grew in a more bushy structure without any training on my part. Plus the cool running temperature (and the fact that plants prefer warmth under this light) makes it ideal for growers struggling with heat.

However, the LEC buds were more sparkly and the leaves were also glistening with trichomes from head to toe. The LEC produced much higher quality trim and more hash. Plus, when it comes to terpenes, the LECs ended up on top with an average of about 17% more terpenes per gram. Therefore the LEC may be a better choice if you’re most concerned with trichome production (for example if you’re making a ton of hash) and/or a complex terpene profile. The LECs are also a great choice for growers struggling with cool temperatures or having a hard time getting plants to grow vigorously under LEDs.

In the end, the real winner was me. Both of the lights produced fabulous weed!


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