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Soil vs Hydroponics: Growing Cannabis
by Nebula Haze
Today, we're going to discuss the difference between growing marijuana with soil or growing marijuana with hydroponics.
What is soil and what is hydroponics?
Soil for Growing Cannabis
Soil is the mineral and organic material found on the surface of the Earth which is a natural growing medium for plants.
Marijuana prefers rich, slightly acidic, high-quality soil that drains well. Many growers supplement their soil with perlite for added drainage. Soil growers also almost always add either liquid nutrients or nutrient-rich materials such as manure, earthworm castings, or seabird/bat guano to make sure the marijuana plants get everything they need.
Organic potting soils often work well for growing marijuana when mixed with perlite. Fox Farm Ocean Forest is a popular soil choice among marijuana growers. Regardless of the soil you start with, most growers will need to supplement with nutrients for the best results.
Popular Cannabis Soil Choice: Ocean Forest Mixed with About 20% Perlite
Plants naturally absorb nutrients from soil, though especially in the flowering stage, it's up to you to provide just the right amount (not too much) of the right kind of nutrients to maximize your yields and prevent nutrient deficiencies.
If you start with rich soil like Fox Farms Ocean Forest, you won't need to add any extra nutrients for at least the first few weeks of growth, but by the time your plant gets to the flowering/budding phase, it's very important you add additional nutrients to support bud growth (since your plant will have already used a lot of the nutrients in the soil!)
Learn more about marijuana soil nutrients here:
Hydro for Growing Cannabis
When growing marijuana hydroponically, as the grower it's up to you to provide all the nutrients your plants need throughout the entire grow. This is done by adding nutrients to their water supply.
The benefit to this is that you can accurately provide the right amount of exactly the right kind of nutrients your marijuana plants want, to maximize your yields.
Common growing mediums for hydroponics (often mixed together):
- Grown directly in water
- Growers often use Hydroton (clay pebbles) to anchor the roots in a hydro system
- Coco coir (coconut shell husks)
- Peat Moss
- Soilless Potting Mix
Learn more about hydroponic marijuana nutrients here:
Growing Weed in Soil Pros & Cons
- Many growers claim soil-grown marijuana tastes better
- Soil can be more forgiving for the inattentive grower since it already contains some amount of nutrients in the soil
- If you've grown anything in soil before, growing cannabis in soil probably seems easier than some types of hydroponic growing
- Marijuana tends to grow slower in soil than in hydroponics in the vegetative stage
- Soil usually returns lower yields compared to hydroponically grown marijuana (when given the same time, lights, and environment)
Popular Cannabis Soil Choice: Ocean Forest Mixed with About 20% Perlite
Growing Hydroponic Weed Pros & Cons
- Total control over nutrient levels
- Faster harvest (you can shave up to 2 weeks off the vegetative stage)
- Less likely to suffer from weeds, soil-born diseases or pests
- Growing in a soilless growing medium like coco coir is almost exactly the same work as growing in soil, yet you get nearly all the benefits of hydro
- Techniques like bubbleponics and DWC give growers the ability to pretty much automate their grow, so it takes a few minutes a week to maintain
- Can correct problems much more quickly in hydro
- Some growers claim hydro grown weed doesn't taste as good, though many growers agree that taste has more to do with your nutrients and flushing methods than purely hydro vs soil
- Plants are quicker to show signs of problems
- Some hydro methods are overly complicated and not beginner friendly
- No natural nutrients so you have to supplement nutrients, which can be as simple as a nutrient system like Dyna-Gro (Grow + Bloom) and as complicated as a full cannabis nutrient system.
Biggest Differences Between Growing Marijuana in Soil vs Hydro
Generally hydroponic and soil-grown cannabis need slightly different nutrients, but there is one nutrient system that works for cannabis in all growing mediums, including soil, coco and hydro. If you're not sure what to get, it may be worth a try. Learn more about cannabis-friendly nutrients.
Optimum pH for Nutrient Absorption
Soil pH: 6.0-7.0
Hydro pH: 5.5-6.5
Even if you're growing in a potting mix, if it doesn't say "soil" you will need to adjust the pH for hydro levels. So if your bag says "Coco Coir" then use the pH for Hydro.
We recently received this question where a reader was growing marijuana in a mix of vermiculite and perlite. Because this seems soil-like, he was adjusting the pH levels as if he were growing in soil.
It's important to note that growing hydroponically means growing in basically anything besides soil, even if it resembles soil.
Here's the question....
Question: I'm growing 3 White Widow plants in soil with High Pressure Sodium (HPS) lights using cannabis-specific utrients. The soil is made up of 75% Perlite 25% Vermiculite and I'm adjusting the pH to 5.5 - 5.9. All my plants seem to be having this problem. Any idea why? Thank you in advance.
Answer: It looks like Magnesium deficiency, but considering your nutrients have plenty of magnesium, and what you said about your pH. I think this is really a pH problem.
Using Perlite and Vermiculite is still technically considered hydroponic (not soil), so you'll need to use a hydroponic pH range (5.5 - 6.5). Magnesium and Calcium especially tend to get locked out when the pH near the roots drops below 6.0. If you adjust the pH to the proper levels, this problem should clear right up.
Also make sure you're testing the pH of the runoff water that comes out the bottom of your pot. This will give you a clue if there's something going on at the roots that is dramatically changing your pH. Good luck!
Hydro and Soil Grown Marijuana Usually Need Different Nutrients
As a general rule, you will need to get nutrients specifically made for soil or hydro. This is because soil provides some nutrients, while in hydro you must provide all the nutrients.
Dyna-Gro is a noted and well-loved exception that works great for growing marijuana in soil or hydroponically. Just follow their instructions at half strength. Use "Grow" or "Foliage Pro" for the first part of the plant's life and then switch to "Bloom" after you see the first flowers growing.
Learn more about marijuana nutrients here
There Are So Many Different Hydroponic Methods, It's Hard to Generalize
Each hydroponic grow method has its own pros and cons, and they're so different from each other it's hard to truly compare "hydro vs soil."
Some hydro growers use bubbleponics of Deep Water Culture (DWC) which means they're growing with their plant roots directly in water.
Other hydroponic growers grow in soilless potting mixes or coco coir, which in practice is extremely similar to growing in soil besides the nutrients and optimum pH.
Here's the simplest way to grow weed in soil. Get Fox Farms Ocean Forest soil and plant your seeds. Water whenever top inch or so of soil seems dry. Start adding a tiny bit of Dyna-Gro Bloom fertilizer to your water after plants start budding and you're good to go!
Growing marijuana hydroponically in bubbleponics tutorial:
Growing marijuana hydroponically in coco coir (with CFLs) tutorial:
You should grow in soil if...
- You really like the idea of growing weed as "close-to-the-wild" as possible
- You have access to good soil or are willing to make your own
- You are willing to supplement with organic compost teas or nutrients as needed
- You feel that soil-grown marijuana tastes the best
- You want something that's more "set it and forget it" and don't care as much about yields or fast harvests
You should grow with hydroponics if...
- You want a faster harvest
- Getting the highest yields possible is most important to you
- You desire the convenience of soil without the pests (hand-water grow in soilless potting mix)
- You'd like the convenience of a close-to-fully automated system (DWC, bubbleponics, etc)
- You are willing to become the sole provider of nutrients throughout the grow
- You love experimenting with different methods and want to tune into the perfect grow method
I hope you enjoyed today's issue. As you may have gleaned from this article, I (Nebula Haze) personally love growing marijuana hydroponically. I believe proper flushing and overall lower nutrient levels give you marijuana buds that taste even better than soil-grown (though my opinion is obviously biased).
At GrowWeedEasy.com, we are dedicated to teaching people how to grow indoors the way they want. We'd love to hear from some soil growers and get more from your side of the story!
If you love growing marijuana in soil, don't hesitate to submit an article or pictures so we can share with the rest of the growing community!
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About the Author: Nebula Haze
Now she grows in DWC using a 250W HPS, check out one of her grows!
In response to the need for more tutorials aimed at new growers, Nebula co-founded GrowWeedEasy.com in 2010 with fellow grower Sirius Fourside.
Since then, Nebula has published dozens of growing articles in print and online, stars in online video lessons, and continues to dedicate herself to serving the needs of the medical marijuana growing community.
"My mission is to show other medical marijuana patients how easy and fun it can be to grow pounds of killer weed out of your closet."