by Nebula Haze
Also Check Out the 250W Coco Coir Grow Tutorial (How to Consistently Harvest 4-7+ oz!)
Any quality cannabis nutrients made for hydroponics will work well for growing marijuana with coco coir as long as you also use a Cal-Mag supplement.
Learn about different cannabis nutrients: https://www.growweedeasy.com/nutrients
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!).
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!
Like nearly all cannabis nutrients, the included schedule is aggressive and can burn your plants if given with every watering. No matter what nutrient system you're using with your coco coir, I recommend giving plain water every other watering to prevent nutrient buildup.
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 for at least two weeks at the beginning of your grow. You may also add Cal-Mag with your other other nutrients if needed throughout the grow, though you may want to give it at lower doses.
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…
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).
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 combo is a crowd favorite – many coco coir growers write in to tell us this is their favorite cannabis nutrient for growing in coco coir. 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.” A different grower added, "Canna – I have only used their coco line, but it is the the highest quality you will find."
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 foir. 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.
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.”
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
- Made specifically for coco or hydroponics
- Coco does really well with either mineral nutrients or organic nutrient sources. With mineral (hydro) nutrients the plants tend to grow bigger and faster, but with the organic nutrients plants may produce buds with a more complex smell. Both types of nutrients produce very high-quality weed, and any differences are relatively small and often very hard to pin down. In our growing forum, many side-by-sed grow tests with organic vs hydroponic nutrients have given inconclusive results!
- 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 – For some reason cannabis is very prone to Calcium deficiencies when growing in coco coir unless you supplement with extra Cal-Mag (it's important to always add Calcium and Magnesium at the same time in a certain ratio, 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. If available, it's always good to get a Cal-Mag supplement from the company who makes your nutrients, because that helps ensure all your nutrients 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).
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!
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)
|Optimal Coco Coir Cannabis N-P-K Nutrient Ratios|
|Vegetative/Grow||High||Medium to High||High|
Additionally, coco nutrients should always include….
Nice but not necessary micro-nutrients (contained in most water sources, but if using RO or very soft water you want these in your nutrients to prevent possible deficiencies)
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 Phospohorus, 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