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Date:
February 11, 2019Author:
Marijuana Growing Educators
Coco coir is a popular root zone media choice for growing marijuana. It can be easy to use, and some growers use it for more than one crop, which saves money. But it often causes problems for your marijuana plantsâharming growth rate, potency, yield and your bank accountâuntil you master these important coco coir factsâŠ
Marijuana Coco Coir Fact #1: Coco Coir Manufacturing Standards
As with manufacturers of gardening soil, soilless mix, and rockwool, there are multiple coco coir manufacturersâand very few make quality substrates.
Coco coir comes from coconut husks. The quality of coco coir depends a lot on where and how the husks are sourced. The quality and age of the husks are also important. Some coconut husks are loaded with sodium and toxic contaminants from ocean water or storage ponds. Other husks are too green and immature to be processed into quality horticultural material.
When coconut husks arenât processed properly by washing them with fresh water at the right temperatures and for long enough, and by carefully treating and drying the material after washing, the resultant coco coir can cause nutrients problems that harm or kill your plants.
Whatâs more, coconut husks have to be expertly processed so they break down into âcoco peatâ fibers with the right water-holding, aeration, internal consistency, and durability for marijuana plants. The processing must be done using professional facilities, methods, and materials. If not, you see inferior coir that tends to become waterlogged or break down quickly, leading to drowning marijuana roots.
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During horticultural coco coir media manufacturing, husks and fibers must be washed and treated correctly or the finished product causes severe feed program problems involving nitrogen, calcium, iron, magnesium, potassium, sodium, and chlorine.
And coco coir must also be graded, packaged, shipped and stored correctly so it works well for your marijuana garden.
Youâre probably wondering whatâs the best coco coir brand. Iâve tested all major brands and many off-label brands, and have experienced intermittent or pervasive problems with all of them, including Canna and Botanicare.
It doesnât help that there are significant variations in coco coir quality batch to batch, even from the same manufacturer.
Ask your hydroponics store what brands of coco coir they most recommend. But no matter what they recommend, take a look at this next factâŠ
Marijuana Coco Coir Fact #2: Wash & Test Coco Coir
No matter what a hydroponics store or coco coir manufacturer tells you about the quality, pre-washing, processing, and usefulness of their coco coir product, itâs best to wash and test it yourself before you use it. What I do is buy the smallest amounts possible of the top two coco coir brands recommended by my hydroponics store. Then I test the products using the following method:
- Put the coco coir in a two-gallon bucket that has holes in the bottom, and place that bucket inside a five-gallon bucket.
- Using reverse osmosis water, pour 2.5 gallons of water at pH 5.7-5.9 through the coco coir, collecting the runoff water in the five-gallon bucket.
- Test the parts per million and pH of the runoff water.
- If the parts per million reading is higher than 450 ppm, and/or the pH is wildly out of range, repeat the experiment to see if you can get runoff water thatâs less than 450 ppm and within pH range.
- If you rinse your coco coir more than three times and itâs still showing 450 or more ppm, and/or the pH is out of range, donât use that coco coir.
- This rinsing and monitoring process take times and you may go through several brands of coco coir before you find a quality product. When I rinse coco coir and the runoff pH is within range and the runoff parts per million is below 300, I feel I can trust that coco coir.
Marijuana Coco Coir Fact #3: Buying the Best Form of Coco Coir
Beyond finding properly-manufactured coco coir that performs well in runoff pH and ppm tests, you want to buy coco coir that has the right consistency and configuration. Coco coir comes in a variety of configurations, including condensed bricks, loose fiber, coco peat blocks, and coco coir fibers mixed with perlite.
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The best way to grade coco coirâs usefulness in your grow op is to wash and measure it, and to physically handle and visually examine it. Youâre looking for dark, clean, golden-brown fibers with the consistency of moderately-dry soil. The coco shouldnât have clumps or fine powder.
Many marijuana coco coir growers use coco in raised grow tables for sea of green marijuana gardening while others use it in individual pots. I donât pay the extra price for coco coir that comes with perlite, but especially if Iâm growing in a grow room that tends towards high humidity, I might cut coco with 10%
coarse perlite. Bricked coco is usually cheaper, but harder to work with. I suggest loose fiber.
And againâremember to first buy a small amount, so you can thoroughly inspect the coco before you buy the larger amount youâll use for your season if you find that the coir is high quality.
Marijuana Coco Coir Growing Fact #4: Watering Coco Coir
Coco coir retains water wellâtoo well if youâre a marijuana grower who tends to overwater. On top of that, coco coirâs appearance isnât a reliable way of knowing when it needs more water. Coco coir should be watered when itâs 50-70% dry. But how can you determine the dryness of your coco coir?
One method works only if youâre growing in individual pots:
- Water until about 15-20% of the water runs out the bottom of the pots and the coir appears to be thoroughly wet.
- Weigh the pots and record their weight. If theyâre evenly watered, theyâll all weigh about the same.
- When you think 50-70% of the moisture has left the coco coir root zone, weigh the pots again.
- The difference between the initial wet weight and the current weight is used in a percentage calculation to determine how dry the coco has become.
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Two other things to know: Coco coir is particularly sensitive to salts and contaminants, because it has chemical and physical properties that interact with water and whateverâs in it in ways that no other marijuana root zone media does, so always use reverse osmosis water.
Be careful not to overwater. Too many coco coir users drown their cannabis roots, which is especially bad for tender seedlings and clones that donât yet have fully-formed root systems.
Marijuana Coco Coir Growing Fact #5:
Some Nutrients Suck
If you use regular hydroponics nutrients or organic nutrients with coco coir, youâll almost certainly see crop problems. I used to hate coco coir, until someone explained to me that it was the fertilizers I was using, not just the coir, that caused the problems.
So the first step in ensuring you can properly feed your cannabis plants in coco coir is to get the highest quality coco coir substrate. Weâve been testing coco coir for years, and have been greatly disappointed by all the major brands. Most of them havenât been processed, washed, or buffered properly. Using these inferior brands, youâre forced to use nutrients made specifically for coco coir, which means they canât be used in other substrates.
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Problem is, most of the nutrients brands that claim to work well in coco donât. Growers are forced to use cal-mag supplements that created more problems than they solve. Growers harm their marijuana plants with repeated flushing, trying different nutrients parts per million concentrations, underwatering, and overwatering.
- Coco coir holds water well, so you water less, and less frequently.
- Coco coir is an ideal host for beneficial, root-enhancing microbes.
- Coco coir can be recycled for use in multiple crop cycles.
- Coco coirâs favorable oxygen/water ratios provide more oxygen to roots and prevent waterlogging (as long as watering is done properly) which increases growth rate and harvest weight.
- Coco coir is a mostly-inert medium that works well with hydroponics and organic nutrients.