Coconut peat or coir was first presented to the Royal Botanical Society in 1862; after initial success, it was relegated to the background due to its inherent problems.
People then believed that coir peat was too much of a problem to use alone, but that it caused impressive indirect results when mixed with potting soil or used as a soil amendment to improve. Today, however, it is a popular growing medium for many plants, including cannabis.
What is coconut coir?
The substrate called “coconut” which is used for growing cannabis is made from the fibers of the bark surrounding the coconut. These fibers are first processed to be leached from the salt accumulated by the sea, then transformed into the coir used to grow plants.
It is a so-called sterile, or inert, substrate which contains no germ, no fungus, no seeds or other parasites. It also does not contain nutrients as is naturally the case with soil.
Coconut fiber has many benefits for the cannabis grower. Its strengths are primarily linked to its shape since coconut is biodegradable, easily reusable, light, and can be compressed into bricks, thus facilitating its transport.
Coconut coir can be used alone or mixed with potting soil to improve its properties (drainage, root aeration, etc.)
How to decompress a brick of coconut?
The first thing you must do is to immerse the brick in water until it returns to its initial shape. This only takes an hour or so, and it is then ready for use.
The advantages of the coco coir growing medium
If coconut is attracting more and more cannabis growers, it is because this substrate has many advantages! It is above all known to optimize yields. If the grower is careful and cultivates their crop correctly, then the harvest will definitely be productive.
An economic choice
Coir is inexpensive; it is made from coconut waste and is reusable. In addition, it requires the use of smaller pots and, therefore, the use of less substrate for each culture. It is essential to grow in smaller containers when using a coco growing medium. If we have to make a comparison with the soil, then a 2-liter pot in coconut is equivalent to a 7-liter pot in soil.
Due to its aerated, porous, draining structure and its ability to stay that way over time, it allows cannabis plants to develop a healthy and dense root system rapidly, which promotes vigorous growth and thus allows faster flowering. It is also a good support for making cuttings.
Thanks to a high level of oxygenation, coconut coir has excellent water draining abilities. For this reason, it is almost impossible to overwater. On the other hand, evaporation takes place more quickly, and the coconut tends to dry out faster than the soil, especially once the root system has developed well. It still has the advantage of rehydrating faster.
Coconut is a neutral substrate that does not contain any nutrients at the start. The nutrient supply to the plant is therefore entirely managed by the grower. The pH and EC testers allow you to keep control over the nutritional conditions of the cannabis plants and to react quickly in case of excess or deficiency.
Coconut contains natural trichomonas which promote the formation and evolution of roots. They stimulate microbial life and increase the natural defenses of plants.
Ideal for beginners
Coconut coir also makes it easy to rectify problems. If you accidentally over-fertilize your plants and the substrate is loaded with salts, then watering them with plenty of water with a little rinse aid will be enough to remove the excess minerals. This has the effect of “resetting the counters to zero”, the substrate being cleaned of all the previous inputs. You can start again on dosages of fertilizer adapted to the needs of the plant.
For growing cannabis indoors, it’s the kind of detail that counts! If the coconut falls on the tiles, even after watering, a brush or vacuum cleaner and nothing appears! Unlike potting compost which can be very messy.
Coconut fiber is a good compromise between soil and hydro:
- Like soil, it is possible to develop the roots of the plant in a healthy environment where many microorganisms flourish happily to allow the plant to develop in the best conditions.
- Like hydro, the control of nutrition is more precise, and it is possible to install a semi-hydro system with automatic watering.
Tips: How to grow cannabis in coconut?
A beginner can get started with coco once the basics of growing cannabis are acquired. However, coconut cultivation has some specificities that are worth bearing in mind.
The importance of using fertilizers at each irrigation
Because the substrate does not contain nutrients, the grower must regularly feed the plants via a nutrient solution dosed precisely according to the stage of development of the plant. It is advisable to start adding fertilizer as soon as the first pair of leaves appear, or as soon as the cuttings are potted. Be careful, however, to start with low dosages so as not to burn the plant which at the beginning of its life has little plant and root matter to consume the nutrients.
The significance of DTW (Drain To Waste)
The drain is what flows under the pot during watering. A DTW watering means the drain will be thrown away. This is the case with manual watering or with an open automatic watering system (see below for more info)
In coco, the volume of the drain must represent 30 percent of the amount of water/nutrient solution supplied to the plant, to avoid the accumulation of salts in the substrate (which is frequent in coco). If the grower brings 1 liter to the plant to drink then about 300ml of water should come out under the pot.
Rinsing every two weeks
As we have seen just above, coconut tends to promote the agglomeration of salts, thus increasing the risk of over-fattening due to an overloaded substrate. To avoid this, we recommend that you water every two weeks with a solution composed only of water and enzymes.
Mineral or organic fertilizers
We can very well cultivate in manual coconut with organic fertilizers following the same principles as organic cultivation in soil. However, mineral fertilizers, as well as the use of PH and EC testers, are a plus for controlling plant nutrition.
Coco only or mixed?
When the grower chooses to grow in coconut, it is often recommended adding perlite or clay balls to lighten the substrate. However, it is perfectly possible to grow cannabis in a substrate made entirely of coconut and achieve excellent results.
Keeping the substrate moist
At the start of cultivation, nothing differs from horticulture in soil. The grower starts in a small 0.75 cl pot and takes care to let the coconut dry out before watering again, to force the root system to develop. Once it has adequately developed, the plants are transplanted into two or 3-liter pots to start the vegetative phase. From this point on, it is strongly recommended not to let the substrate dry out too much, knowing that the coconut will dry out faster than the soil.
PH and EC levels
When using mineral fertilizers, carefully monitor EC measures to avoid the build-up of salts that could be toxic and harmful to the plant. If the drain exceeds the acceptable EC measurements according to the stage of development of the plant, the substrate should be immediately rinsed with enzymes or a rinsing solution such as Florakleen or Final Flush, passing 2 to 3 times the capacity of the plant. Water retention of your pot. (See EC measurements according to the different stages of the cannabis life cycle)
Whether during the entire culture or during a rinse, you will always need to adjust the pH of your solution. In coconut, it is advisable to maintain a pH between 5.5 and 6.3. Depending on the stage of development of your puppies, you can vary the pH in order to match their needs best.
Coconut coir watering
When it comes to watering you have two options. DTW manual watering and closed circuit. Read more about these forms of watering below.
DTW manual watering
This has the advantage of being the least expensive and of being able to adapt the dosage of fertilizers during watering according to the needs of each plant. On the other hand, it is the most tedious.
It is highly recommended repotting your plants in 6-liter pots before the flowering phase, to make it easier to keep on top of the daily watering.
Unlike a DTW system, a closed circuit drops the nutrient solution back into the tank to be reused by the pumps for watering.
For a long time it was thought that coconut could not be used in this way and yet more and more people are doing it successfully.
You need almost the same material as an open circuit DTW as well as nozzles and one less tank. Closed circuit is also less expensive because the solution is not thrown away but reused so no water or fertilizer is wasted.