Adventures in Growing Cannabis in Coir
As a cannabis grower, many moments stick out in your mind as aww haw moments when the way you’ve been growing suddenly changes for the better. As a dedicated soil grower, I tended to ignore advice about using other substrates other than soil. I figured if it was good enough for mother earth, it’s good enough for my plants.
It wasn’t until I went to visit another medical grow and witnessed the difference between cannabis grown in soil and cannabis grown in a substrate such as Coco Coir. That day I had my eyes opened to the massive potential of growing in Coco Coir. I’m now going to share with you everything I learned that day that changed the way I grow forever.
Why did I make a significant change from soil to coco? By the time you finish reading this short article, you’ll know exactly why, and you’ll want to do the same!
What is Coco Coir?
Coco coir is a waste product made from the natural fiber of coconut husks. Found mostly in India, the Philippines, and Sri Lanka. In the past, this fiber was tossed away until some smart people figured out its amazing properties as a grow medium for both indoor and outdoor plants. As new Coco coir, the material generally has a pH balance of between 6.5 and 6.7 which is like natural soil.
Coco Coir is available from grow shops in 25- and 50-pound bags as well as in small compressed bricks.
While coco does itself contain some level of basic nutrients, if you’ll be growing cannabis with it, you’ll need to fortify your grow with a proper cannabis nutrient combo. I used nutrients by Remo, a great Canadian manufacturer.
Coco Coir isn’t recycled just once, you can use it up to three times before the fibers start to decompose. After each grow, you’ll need to rinse the Coir fiber very thoroughly with water with a pH between 5.8 and 6.2. This wash of the substrate will remove any mineral and fertilizer salts from the fiber.
How Do I Grow Cannabis with Coco Coir?
As I started to research how to grow cannabis in coir, I found that many growers are already mixing soil with coco coir to create super soil mixes that improve the growing potential of cannabis plants. But why stop with a mix? Wouldn’t using 100% coir be better than mixing it with soil?
FACT: Coco coir is an extremely fibrous material allowing it to hold more water than soil while providing the root system of your plants more oxygen. Space for oxygen to contact the roots comes from the massive amount of surface area the fibers of coir contain.
To truly get the best results with coco you should be mixing it with 20% to 30% Perlite which will increase the air space in the root area. Perlite is a volcanic glass which allows water to be trapped inside its structure further increasing the substrates ability to hold water for longer periods.
INSIDER TIP: Don’t cheap out on your Coco Coir, buy the best available to you. Lower quality coco is known to have higher salt contents which can cause a problem for your plants. If you purchase cheap coco, you’ll need to wash it in pH corrected water first.
Brick Coco Coir is what I like to use. No need for messy bags being stored. The little brick stores away easily until it’s ready for use. To use it just place it in a large bucket or sick with 4-5 liters of pH 5.8 to 6.2 water. Let it soak until the fiber starts to expand and come apart. Once soft the brick will break apart easily. Now add two to three liters of perlite and mix well with your hands. You're ready to grow!
Feeding Cannabis When Growing in Coco Coir
Any new grower or experienced hydro or organic grower can easily make the transition to Coco coir. Generally, liquid nutrients like those found in multi solution fertilizer systems will work best for growing in coir, but some soil specific nutrients will work as well (check with your manufacturer). There are specific nutrients made for Coco coir such as the options made by Advanced Nutrients and though they are tailor-made for coco, and great, you may have nutrients already that should work almost as well.
IMPORTANT NOTE: Coco coir is a great grow medium option, but it has one shortcoming. Coir doesn’t hold on to calcium very well meaning you’ll need to boost your Cal/Mag supplements to about 15% over manufacturers recommendations to avoid any issues.
Coir allows the grower some forgiveness when it comes to pH fluctuations, but you really need to be growing with a proper pH meter so you can keep your water/nutrient mix between 5.9 and 6.1 for adequate nutrient uptake.
Watering/feeding your plants in coir is no different than dealing with plants in soil. Provide ample water to wet the roots, then to check if the plant is dry just lift the pot and check if it’s become light. If the top inch of the coir is dry to the finger and the pot is getting light, it’s time to water.
Coco coir is different than soil in the fact that it contains lower naturally occurring base nutrients. This means that your coco grow will need significant levels of nutrient solution from day one until your final two weeks of flowering.
How to Keep Your pH Correct
There are nutrient blends that come pH balanced perfectly, even so, you’ll still need a pH meter to verify the water pH before the nutrients are added. To pH your water you’ll need a pH meter, a bottle of pH UP and a bottle of pH Down. Check the waters pH with the meter, if the water is too alkaline you add a tiny bit of pH Up, if the water is acidic add a little pH Down and check with your meter again. Follow this process until your water is in that 5.9 to 6.1 range.
If you aren’t using coco specific nutrients, you will run into a few situations which you’ll need to correct and watch out for. Coco Coir cannot hold on to calcium efficiently causing a need for increased Cal Mag supplementation. You could also run into an issue with iron which needs to be supplemented as well.
Advantages of Growing Cannabis with Coco Coir
In general Coco, coir is a forgiving and easy to use grow medium once you’ve got a system dialed in. If you start with proper water and nutrients, you really shouldn’t have any unexpected issues with your grow.
1. Great for your Plants Roots
Coir has a one of a kind attributes, and that’s it’s the ability to hold water while still providing millions of tiny oxygen pockets within the root system of your cannabis plants to breath. Unlike soil which needs to dry out almost completely between feeds to ensure oxygenation. Another reason coir is a great grow medium is that it also retains phosphorus exceptionally well so that your plants will yield larger buds.
INSIDER TIP: Don’t use plastic or ceramic pots for growing cannabis. A better option is a fabric pot which further allows oxygen transfer from the atmosphere to the root system by way of the air pockets in the Coco coir.
2. Ecofriendly and Completely recyclable
Coir is a natural by-product of coconut; nothing more then husk fiber. So, when you get coco coir, it’s already the second use of the material. A safe rule of thumb is you can use your coir 3 times before you put it out to pasture as mulch. The Coir fibers will start to break down over time, so it’s best to retire it before it starts to lose its structure.
3. Fewer Insect Infestations
I’ve had it happen many times, I bring home a bag of potting soil that’s infested with eggs. A month into the grow you start to notice pests; these guys came with the soil. This does not happen with coco. Its material is resistant to root rot, fungi, and insects so as a grower you have much less to worry about.
4. Coco Coir = Growth Improvements
There is no doubting the benefits of Coco Coir after having a successful grow with it. You’ll notice better, faster vegetation right away because of the useful water/nutrient management coir provides. That extra oxygen in the roots coupled with having more water/nutrients in contact with the root system increases plant growth and health.
Don’t be Afraid to Stretch your Knowledge
I’m guilty of staying in my “lane” because I’m satisfied with average results. Making changes to your growing procedures brings risk to your crop and I’m risk adverse. You’ll never achieve greatness by not taking risks.
Coco coir does represent a large improvement in growing cannabis, there are differences and procedures to learn to be successful, but that little bit of studying is well worth the investment of time. Read this article a couple of times, make sure you investigate your nutrient situation ahead of time and get growing!
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