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Using Coco as a Substrate

Smokin Moose

Fallen Cannabis Warrior
Coco produces excellent results for the soilless grower; it is comparable in result to hydroponics systems.

It is a great alternative to the soil grower willing to experiment with a "soilless" medium, yet get comparable results to a hydro grow.

Coco can be used in a hydroponics system, or just put into pots and watered by hand as with any other soil grow. Countless grows for decades have been produced in plain soil, mixed with organics, compost, and perlite among untold other ingredients thrown in.

While soil does have its advantages, it also has more drawbacks: inconsistancy, unwanted (unknown) ingredients, increased chances of over-fertilizing and over-watering. Nearly all of the potting soil used has been sourced from nature contain larva and insect eggs.

*Pics shown which I grew in Coco are only 30 days into flowering, 60 days old from seed, with an intentional N def. They are not as yellow as shown. I have provided them to show the crystal/pistil covering bud/leaves more common to hydro in this stage of flowering, yet grown in coco-filled pots

The Definition of Coco
Many at first are misled by the use of the term Coco. It has nothing to do with the Cocoa plant at all. In reality, they are the brown fibers that make up the husk of a coconut, which have been washed and buffered. Pure Coco can be used as a substrate, or Coco can also be mixed in with soil.

It can be bought loose in bags; it is also pressed into planks (and bricks). Coconuts are found near beaches, oceans, places that have very salty air. To rid the coco of these salts, the coco is first washed, and then pressure steamed to get rid of salts, and bacteria, germs or anything else that might have been in it. Coco is buffered using water, enriched with Magnesium and lime. The quality of this treatment is dependant to the quality of the Coco. Coconuts cannot be bought from a store, pealed, and mixed into your soil.

(Edit: low quality coco may need to be washed to remove natural salts.)

Coco and PH
The buffering process also means easy adjustment of pH in the Coco, which is imperative when it comes to the optimum uptake of nutrients throughout the plant's life.

Soil PH can be hard to change, since it takes time to correct, flow check and restore. It takes longer to correct the problem in soil, than it took to cause it.

The PH of fresh Coco is marked on the bag from 5.0 - 7.0, however all of the coco I've tested was always between 6.0 - 6.5. Changing the PH of Coco takes a few waterings of pH-adjusted water, perhaps only one. The medium is very reactive to the PH of the water given to it; this gives coco growers rapid control over pH.

What is important is that you use 6.0 - 7.0 pH water, 6.5 being optimal if in pots.

Oxygen and Coco
Soil has a tendency to become finer after time. The clumps of soil quickly disintegrate, leaving very fine pieces of matter which hold moisture, creating saturated spots, making the soil less and less aerated for roots over the plant's life. The soil at the bottom of the pots can become a very hostile environment for the roots to grow, making roots suffocate in mud. Coco users rarely find this a problem. Coco almost never disintegrates, leaving the medium well aerated, supplying the roots constantly with enough oxygen, and all saturated spots quickly even out.

Reusing Coco
Another advantage of Coco is the fact it can be re-used. Because Coco is treated so well, you can get up to three grows from the same batch of coco. Coco is inert and does not absorb nutrients within its own fibers, so plants uptake only supplied nutrient-rich water; excess nutrients and salts are washed through with the overflow.

I paid 8 Euros for a 50 Liter bag of coco. 24 Euros in Coco, and I can fill a total of 9 seventeen Liter pots (4.5 gallon) 3 times over. Those 27 plants could go through flowering, and only averaged to .88 euro per pot in coco.

Before reusing coco, you must sift through the Coco looking for any loose root fragments, missed decaying leaves, ect. and remove them.

Advantages and drawbacks
Coco overall has many distinct advantages over soil. I have yet to grow a plant in Coco that hasn't reached 2-2.5 feet in just 1 month from seed, without any stretching until later in life (without Topping or Fimming). The evenness of watering and the quick and direct changes of pH compares to hydro. The cost isn't that steep because it can be reused up to 3 times, making the average cost (for myself) .24 cents US currency per US gallon. Well, after using coco, I'll never use normal potting soil ever again

The only drawback to Coco I have found is that a massive root ball forms very quick while in veg., all my plants were detrimentally root bound in 7 Liter (1.85) gallons of coco after only 3 weeks of growth from seed. If you are ready for the growth, being in pots, and hesitant at all to go hydro with supplies and adjustments, it's just a small hurdle for all the benefits.


Member of the Month: Dec 2012
Great info indeed :thumb: I grow in coco coir and love it


New Member
going to try and posts some pics of some of my plants in coco' always grew in soil before this grow. Hope I can get these pics on line< they are behond weird.


New Member
Coco produces excellent results for the soilless grower; it is comparable in result to hydroponics systems...

The only drawback to Coco I have found is that a massive root ball forms very quick while in veg., all my plants were detrimentally root bound in 7 Liter (1.85) gallons of coco after only 3 weeks of growth from seed. If you are ready for the growth, being in pots, and hesitant at all to go hydro with supplies and adjustments, it's just a small hurdle for all the benefits.

Okay, I know this thread is 8 years old, but I just got a hit on something that someone else posted recently about controlling root balls, and could potentially apply with coir or coco medium.

Here's my thought, if one were to control the "root ball" effect by constantly increasing the container size during the earlier stages and lesser degree after final veg. and not at all during flower. In other words, by the time the roots finally reach the outside of the container, you increase the container size slightly, thereby stimulating more expansive (and potentially explosive) growth spurts. :3:

I've worked with arborists, where it was discovered that trees and their roots have a "memory" effect, and "learn" from fibrils and other fibrous root searches. Another way of saying this is, a tree or plant send out tiny fingers in search of what it wants and needs. If they find it, the tree or plant places more resources on the structure of utilizing that supply chain. If it meets with less than optimal to dismal results, the plant root development doesn't continue there and moves onto another area in its ongoing primal search.

Trees along roadsides in cities across this country have sent out their roots underneath sidewalks which, due to their inherent permeability, porosity and tendency to accumulate moisture on the undersides, provide exactly what the roots are looking for... a stable source of cool moisture and filtered nutrients. They tree sends more resources, the roots get thicker, sidewalks lift, then someone often comes along to trim the tree roots to prevent people tripping, and the tree ends up dying. When the tree roots are diverted toward more permeable and modular sidewalk surfacing edges, the fibrils can more easily be detected and trimmed without affecting the tree's health much, if at all. The tree ends up sending it's fibrils and roots deeper in search of what it wants and needs, and the problem corrects itself naturally without affecting the health of the tree. I've worked in this area for years, and this was proven by the Dept. of Forestry.

Anyway, continuing along this path using coir, I understand and accept the roots quickly move toward the outside seeking what they want and need, often limited by the thick accumulation of root mass (root ball), which may tend to slow down the explosive growth. If we were to limit the initial and subsequent root expansion phases, always providing more room throughout the veg cycle, then might it not be likely a more diverse root structure is accomplished? :hmmmm:

Here's my hypothesis, which I feel is worthy of a test, and I'm at just the right point to initiate this:

:idea: The root structure achieved through the use of coir or coco as a growing medium, allows for equal if not greater expansion of both root and plant growth over hydroponics or normal soil.

I don't necessarily feel hydroponics produces a higher volume of greater potency results over soil, and yet feel this could be possibly improved with the hybrid characteristics of coir or coco. It essentially provides the benefits of easy adjustment of pH and nute levels, as well as humidity, but could potentially dry out quicker than soil. There are a host of issues with hydroponics, especially with the growing mediums (unless you're going full fog/mist based systems, which are quite intensive). With soil, as mentioned in the beginning, you never know what you're really getting in the "mix." So properly sources coir is a great growing substrate, fairly inert, doesn't accumulate excess solids, allows for quick aeration, etc.

Here are the steps I'm thinking of going with (and documenting, if I do):
  • Germinate in small 2"x 2" cubes, with rock wool, etc. being okay for now. Placing the seed in, pointed end up, covering it, keeping it moist, with appropriate heat and light for 3-6 days.
  • Once the sprouts have emerged and the roots are starting to collect around the bottom of the cube, transplant into a slightly larger 8 oz cup with coir, holes in the bottom, maintaining moisture, starting nutes lightly, with lots of light.
  • Transplant into a red plastic cup when the roots have started to accumulate around the bottom, and continue the regimen.
  • Transplant again into a larger container at the same root expansion point, and continue.
  • Once the plant has gone through a number of growth spurts and successful transplants in successively larger containers, the root structure should be at a mnassive scale of webbing throughout the coir, and can be moved into a 5 gallon Phat Boy planter (12.75" dia)

It is at this point that the plant(s) should have had some massive vegetative growth, and hopefully lots of complex root structures that have up until this point have not resulted in any root mass or root balls that might become limiting during the crucial veg growth cycle. At the same time, it's likely the roots have continually sought out the edges of its confinement, gotten what they want, and the plant has responded appropriately.

It's very important the plant is placed within successively larger smooth sided containers from which the plants can be observed from a translucent container and/or the plant's roots can be easily observed/checked and removed for transplanting without any significant shock to the plant and roots.

It's also more important that proper controls on the types and amounts of water, pH, light & spectrum, nutrients, etc. are maintained consistently and adjusted as needed.

At the final vegetative growth stage into flowering, hopefully the plant's root system is very robust within the Phat Boy 5 gallon fabric planter, and can be tended to with spreading, SCROD, or other methods, with the benefits of the air pruning along the edges of the container. At this point, I'm not sure if I'd even want to keep and re-use the coir and container, given their relatively low costs.

Okay, that's all I think about that... for now. I'll let my subconscious work on it after a puff or two and some sleep. :tokin:

Hmmmm... I like projects in my sleep! :55:


New Member
Hey piano man, love your writeup... did you ever follow through on this? I'm in a really humid cold area and used soil with LED.. I put them straight from little half gallons to final 3 gal pots and it was hard not to overwater... they just didn't drink enough in those big pots. Would have been smart to add more drainage media to it, but I think I'll go with coco this time and an auto water once I figure out the right amounts...

Would love to hear your results and anyone else's input


Well-Known Member
Want to avoid your plants getting rootbound? Use Air-Pots. I can grow 6' plants in a 9 liter container and they never get root bound.
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