by Nebula Haze
What Makes Nutrients “Good” or “Bad” for Growing in Coco Coir?
When growing cannabis in coco coir, you don’t necessarily need nutrients made specifically for coco. Just about any quality cannabis nutrients made for hydroponics (and some nutrients made for soil) will work great, especially if you use a Cal-Mag supplement. This article will teach you what to look for when choosing coco nutrients for your marijuana plants.
There are coco-specific nutrients, which we’ll go over today, but any cannabis nutrients made for hydroponics will work with coco coir, especially if you add a Cal-Mag plant supplement (coco-grown plants crave lots of Calcium!).
Learn more about cannabis nutrients: https://www.growweedeasy.com/nutrients
I personally like the General Hydroponics Flora trio plus Calimagic (a Cal-Mag supplement) for growing in coco coir.
This is a tried and tested nutrient system for any type of hydroponic growing including coco coir. You can actually follow their nutrient schedule listed on the included nutrient schedule; it’s formulated for plants like cannabis.
Note: After adding nutrients (or even if you’re giving just plain water), always pH your water to 5.5-6.5 before giving it to your plants. This is important!
Give nutrients at half-strength to start
Like nearly all cannabis nutrients, the included schedule is aggressive and can burn your plants if given at full strength. No matter what nutrient system you’re using with your coco coir, I always recommend cutting the amount of nutrients in half compared to what you see on the bottle or from the company, and only raising the amount if the plant is started to get pale or llime green colored (which is a sign it needs higher levels of nutrients).
Tips on giving the right nutrient strength
- Give lower nutrient levels the more often plants get watered. Example: If watering your plants every day, half-strength nutrients are usually plenty. You’re constantly adding nutrients to the “system”.
- Give higher nutrient levels if plant is watered infrequently. Example: If you have small plants in a big pot of coco (like a seedling in a 5-gallon pot), chances are you only need to give a little water every several days in order to prevent plants from getting overwatered. In this case, give nutrients at full strength. Remember, plants in coco only get the nutrients you provide in the water. If you’re not giving water often, it means you are not adding many nutrients to the “system” at a time so need a higher dose.
- Always look at plants to see what they need! Plants tell you what they want. The picture below shows what cannabis plants look like when they’re getting low nutrients vs the right amount of nutrients.
Guide to whether you need to increase the amount of nutrients you’re giving to plants
Most of this plant’s leaves are a dark hunter green. Dark leaves mean the nutrient dose is too high and should be reduced. Although not really a problem in the vegetative stage, this excess suppresses bud growth in the flowering stage (buds don’t get as big as they could).
Test the pH to prevent nutrient deficiencies
Whenever using liquid nutrients, you will need a way to test pH so your plant roots are able to easily absorb all the nutrients they need. I use a simple General Hydroponics pH test kit. Learn more about managing pH here: https://www.growweedeasy.com/ph
How much Cal-Mag should I use for coco coir?
Give Cal-Mag at full strength alongside your nutrients until the plant stops growing new leaves and stems, which is typically during the second half of the flowering stage. At that point, either cut the dose in half or stop giving altogether as the plant is no longer using as much.
Here are some additional nutrient suggestions for growing in coco coir:
Nutrient Picks For Growing in Coco Coir
Often when growing cannabis in coco coir, it is helpful to supplement with extra Calcium and Magnesium as calcium deficiencies & magnesium deficiencies are relatively common in coco coir. There are many supplements that provide a boost of these nutrients, and pretty much all of them will work fine. A commonly seen one called “Cal-Mag” by Botanicare works well (and is pretty inexpensive), and so does “CaliMagic” from General Hydroponics. Coco coir is an excellent growing medium as long as you maintain the pH between 5.5 – 6.5 and make sure the plants have enough calcium and magnesium.
Any quality cannabis nutrients made for hydroponics will work well for growing in coco coir as long as you also use a Cal-Mag supplement.
I personally like the General Hydroponics Flora trio plus Calimagic (a Cal-Mag supplement) for growing in coco coir. This is what I use for my coco coir grow. You can follow the nutrient schedule provided by GH as long as you provide plain water every other watering. Or…
Here’s the custom Flora Series + CaliMagic nutrient schedule I use for coco coir [PDF]
You don’t need any other nutrients to grow marijuana; the Flora trio + Cal-Mag will give your cannabis plants what they need to flourish through the vegetative and flowering stages.
For the easiest coco coir growing, get a smart pot (pot made out of fabric – they work perfectly for growing cannabis and have good drainage).
IMPORTANT: Root pH Affects How Well Your Cannabis Plants Can Aborb Nutrients!
- General Hydroponics Flora Series Nutrient Trio & CaliMagic<– Tried and tested nutrient system for any type of hydroponic growing including growing in coco coir. This version of Cal-Mag (CaliMagic) has been created by General Hydroponics, the same company that makes the nutrients. I use this combination for my grow.
Here is the coco coir nutrient schedule I’m using right now [PDF]
- Canna Coco A + B & Cal-Mag <– This cannabis-specific nutrient line is a fan favorite for growing in coco coir and has many dedicated followers. From a grower: “Canna is a Dutch company and one of the best IMO. They make a great product line for growing in coco coir and test their products on real cannabis plants.” Another grower said, “Canna products are one of the only nutrient lines to be developed primarily for cannabis (and tested on live plants). They’ve been doing so for almost 30 years. Cost is a little higher than competitors but worth every penny.”
- Get a custom nutrient schedule from Canna or use this pre-made one [JPG].
- Fox Farms Nutrient Trio for Hydroponics & Cal-Mag <– Very concentrated, less is more. This is what I used for my first few coco coir grows, and I was very happy with my results. “Grow Big” & “Tiger Bloom” provide most of the major nutrients your cannabis needs, while “Big Bloom” has many micro nutrients and beneficial compounds that help nutrient uptake and root health. This trio works extremely well by itself, just follow the feeding schedule (here’s a PDF, here’s a JPG) from Fox Farms. They offer a lot of supplements, but the only bottles you need to be successful growing cannabis is the FF trio, which is highlighted in green on the schedule. The trio tends to be strong, so use it sparingly (especially “Grow Big” & “Tiger Bloom”). Generally the Fox Farms nutrient system will prevent Cal-Mag deficiencies, but it’s good to have extra Cal-Mag on hand just in case whenever growing cannabis in coco coir.
- Dyna-Gro (Foliage-Pro, Bloom) & Cal-Mag <– Cheapest nutrients that work well for growing cannabis in coco coir. Use “Foliage-Pro” during the vegetative stage, and “Bloom” during the flowering stage. Just follow the instructions on the bottles!
- House & Garden Line-up (expensive yet remarkably effective) Coco A + B, Roots Excelurator, Algen Extract, Bud XL, shooting powder <– Get a custom nutrient schedule directly from the people at House & Garden via their free online nutrient calculator. I’ve never really heard a complaint about this line, and when I visit the local hydro stores, this is the nutrient line often gets recommended as the “high end”. From a grower: “H&G was started by a top researcher from Canna. They are right outside of Amsterdam and because cannabis is legal there, so both Canna and H&G are able to do R&D using cannabis. I don’t know about Canna, but I know that House and Garden makes all their own nutrients in house and they work great.”
- Botanicare Pure Blend for Hydro (Grow + Hydro Bloom) & Cal-Mag <– Botanicare is a trusted company and this line has been a popular nutrient for growing cannabis for years. I’ve seen growers get good results with it, but I’ve never tried this line myself. That being said, I have used their Cal-Mag product with great success, and their Hydroguard is an essential root supplement for me when growing in hydroponics.
What makes Coco Coir nutrients “good” or “bad?”
In other words, why are some nutrients better than others for growing cannabis in coco coir? What kind of coco nutrients need to be avoided when growing marijuana? Do you need expensive nutrients to get good results, or will cheap nutrients get the job done?
With all the different bottles of marijuana nutrients out there, how do you know which one is best for your coco coir growing setup?
When it comes to choosing nutrients for growing weed in coco coir, there are a few considerations that are really important!
Best Nutrients for Coco
Nutrients that are specifically made for coco or hydroponics tend to be the easiest to work with- Coco does well with either mineral nutrients or organic nutrient sources. With mineral (hydro) nutrients the plants tend to grow bigger and faster because the nutrients get delivered to the plant in the most efficient form. It’s often said that organic nutrients result in buds with a more complex smell, but organic-grown plants are a little slower to grow. Both types of nutrients produce very high-quality weed, and any differences in the final product are relatively small and often very hard to pin down. In our growing forum, the side-by-side grow tests with organic vs hydroponic nutrients have given inconclusive results as far as bud quality! The most important thing to pay attention to when growing in coco is good watering practices and paying attention to pH.
- Contains rich sources of micro-nutrients (to make up for what might have been found in the soil)
- Optimum NPK ratios (more info below)
Poor Nutrients for Coco
- Made specifically for soil, especially if you look on the back and don’t see Magnesium, Calcium, Sulfur and other micronutrients on the label. A lot of soil-made nutrient systems will work for cannabis, but they often skip out on micronutrients which would normally be found in soil, but might not be available in coco coir. If you’re using filtered or RO water, it’s even more important to use nutrients designed for hydro or coco since there will be basically zero traces of other nutrients in the water.
- Low in Calcium – Cannabis is prone to Calcium deficiencies when growing in coco coir unless you supplement with extra Calcium and Magnesium (it’s important to always add Calcium and Magnesium at the same time because they rely on each other and too much of one will cause a nutrient problem with the other). Most coco-specific nutrients already have high levels of Calcium, but it’s also really common to add a Cal-Mag supplement to your regimen when growing weed in coco coir to add extra calcium just in case. Any Cal-Mag supplement will work, but it’s always good to get a Cal-Mag supplement from the company who makes your nutrients jf available. Sticking with the same company for all your nutrients helps ensure they will be compatible with each other.
You can learn a lot about nutrients by looking at the label!
Optimum NPK Ratios for Coco Cannabis Nutrients
N-P-K stands for Nitrogen-Phosphorus-Potassium, which are the three most important plant nutrients. These are what the 3 numbers listed on the front of all nutrient bottles stand for (Potassium is represented by “K” because chemists use the symbol K in the periodic table for potassium).
So what are the optimum NPK values for growing cannabis in coco? It depends on the plant’s stage of life (N-P-K are the 3 numbers on the front of nutrient bottles, like this)
In order to get the best results growing cannabis in coco, it’s important to give the right ratio of these crucial nutrients so the plant gets what it needs at the right time. For example, if you give too much Nitrogen in the flowering/budding phase, it actually surpresses bud production and reduces your yields even if the plant is completely healthy! You don’t want that!
The most important thing is high Nitrogen in the vegetative stage, and low Nitrogen in the flowering stage
| Optimal Coco Coir Cannabis N-P-K Nutrient Ratios | ||
| Life Stage | N | P & K |
| Vegetative/Grow | High | Medium or High |
| Flowering/Bloom | Low | Medium or High |
Cannabis plants grown in soil are not that picky about P & K. As long as there is an abundance of each, the exact ratio isn’t as important as the amount of Nitrogen compared to the others. Additionally, coco nutrients should always include….
- Magnesium
- Calcium
- Iron
- Sulfur
Nice but not necessary micro-nutrients (these are contained in most water sources, but if using RO or very soft water you definitely want to add these nutrients to prevent possible nutrient deficiencies)
- Boron
- Cobalt
- Copper
- Manganese
- Molybdenum
- Zinc
The main difference between NPK ratios for coco and soil are….
- Coco nutrients usually contain more micro-nutrients (in trace amounts), to make up for what the plant would have been able to find in the soil
- Soil nutrients tend to have higher levels of Phosphorus, because microorganisms in the soil (as well as clay “colloidal” particles) can ‘steal’ some of it
When set up right with good nutrients, coco can produce some beefy buds!
Optimum pH of 5.5-6.5 <—- Sooooo important in coco
No matter which nutrient brand you’re using, even with chelated nutrients, cannabis roots are better able to absorb some chemical forms of nutrients than others. This is where pH comes into play. When the pH at the roots is too high or too low, it actually changes the chemical form of the individual nutrient compounds, making it more difficult for your plant to absorb the nutrients it needs.
With coco cannabis nutrients, they’re designed to be most available to your plant when the pH is between 5.5-6.5. If you let the pH get higher or lower than this, you will start getting nutrient deficiencies even if literally everything else is dialed in!
Learn how to adjust your pH to prevent nutrient deficiencies
(It’s easy! It’s kind of like a supplement you add to your reservoir to get better growth)
Stay skeptical of companies that say their nutrients will “automatically” adjust the pH of your water. Although some nutrient systems may be better than others at stabilizing pH, you still need to check the pH regularly if you want to get the best results in coco. Seriously, this is really important!
Depending on your starting water, “PH Perfect” nutrient systems sometimes aren’t able to correct the pH to the right levels, at least not consistently throughout the grow.
This could happen for various reasons. For example your source water likely contains minerals and other “stuff” that will change the pH of your water. If you start with highly purified water instead of tap water, it can actually make pH swings worse because there is no “buffer” in pure water to stabilize pH.
Plus, the amount of nutrients you use changes depending on your plant and its stage of life, and changing the nutrient levels will almost always change the pH, too!
If you check the pH and it’s in the right range, that’s perfect and there’s nothing else you need to do. But don’t skip checking the pH just because the bottle says you don’t have to!
At the very least, make sure pH is the first thing you check if you start seeing nutrient problems!
If you think you have the best coco cannabis nutrients, tell us about your results!
More on Cannabis Grow Mediums…
- 250W Coco Coir Grow (How to Consistently Harvest 4-7+ oz!)
- Soil vs Coco vs Hydro
- Basic Soil Guide
- Organic Soil Compost Guide – Just Add Water!
- Coco Coir Guide
- Hydro/DWC/Bubbleponics Guide
- “True” Organic Growing vs Just Using Organic Nutrients
