best coco coir for weed

Best Coco Coir Nutrients for Cannabis?

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!).

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:​

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…

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).

    House & Garden Line-up (expensive yet remarkably effective)Coco A + B,Roots Excelurator, Algen Extract,Bud XL, shooting powder

    Botanicare Pure Blend for Hydro (Grow + Hydro Bloom) & Cal-Mag

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 If you think you have the best coco cannabis nutrients, tell us about your results!

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 add a Cal-Mag supplement. Learn what to look for!

Best Brand Coco Coir


so whats the best brand now days that doesn’t need pre rinsing ?


I don’t have an answer, just another question: Do you really need to avoid pre-rinsing? I’ve used all sorts of coco, but after one bad experience I always rinse and pre-treat it now. I’m much more re-assured and rest easier knowing for sure that the coco is free of salts (because I measured the rinse runoff ppm), and adequately pre-loaded with nutrients, calcium and magnesium (because I put the nutes in there and measured).

Oh, on topic — I did find my last few Botanicare coco bales to measure very low on initial runoff ppm.


those are the two answers I would give, except that Canna Pro + is NOT full coco. However, after doing some research, Canna is the only brand that determined the BEST way to pre-rinse coco. They also added specific nutrients, humic (and or folvic) acids, and tricoderma mould (a benifitial microbe).

It isn’t that expensive either. Only about 10-15% more expensive than the next brand on the list (attami B’cuzz, in the same form, pre-wetted bags)

While Canna coco is already “the best” in my oppinion, the only thing I’ve found that works better than good nutrients with canna, is CANNA nutrients, with canna coco. just follow their direction (ml per gallon) and use all additives, you’ll thank me some day 🙂 if onyl in your thoughts. Sure, the rhizotonic is like $50 a litre, and the “boost” is $110 a litre, with 15ml per gal (initial, dropped to 5 ml/gal) for rhizo, and 9ml per gal in bloom fro boost. I find that every ounce of ganj produced requires $20-$35 in consumables (nutrients and substrate, electrical is always extra) It’s easy, and makes you feel like a scientist, not a snake oil hawker

so whats the best brand now days that doesn't need pre rinsing ? :stonedsmilie: