Soil Alternatives – Coconut Coir
Those who have never grown marijuana before often assume that the best way to grow plants is to just toss the seeds in some soil, apply some fertilizer, and water them regularly. This is simply not the case. Growers who want to produce high-quality crops and get decent yields need to explore more advanced options, and coco coir is one of the best of them. Read on to find out everything growers need to know about using coco coir in hydroponic and soil-based grow operations.
What Is Coco Coir?
Coco coir, also referred to as cocopeat, coir peat, coconut fiber, or simply coco, is made from tissues known as mesocarp found in the seed husks of coconuts. This natural, renewable material can be reused as many as three times before it needs to be replaced and, when that happens, it can be composted as it is completely biodegradable.
Coco coir contains all the nutrients required to grow a coconut tree, so needless to say, it provides a fantastic medium for growing many kinds of plants, including marijuana. Since it’s also cost-effective and ecologically friendly, experienced organic growers consider it one of the best substrates for growing cannabis.
Coco Coir vs. Soil
Once it’s been ground up, coco coir feels a lot like soil. It also contains plenty of organic material, so it also acts a lot like soil. There are, however, some important differences.
Water Retention and Aeration
Coco coir offers growers a higher level of control over nutrients and water retention. This material offers better drainage and more aeration than most soil, as well. Finely ground coco fibers have more surface area than soil, which traps oxygen near the roots and provides plenty of aeration. When used properly, it creates a perfect environment for growing larger, heavier-yielding plants.
When dry, coco coir is much lighter and less dense than garden soil. It feels almost fluffy. The reason it’s so light is that this material has a huge surface area that allows plenty of oxygen to infiltrate. The fibers can hold plenty of water, but they don’t do so at the expense of oxygenation. Regular soil is harder to work with since it’s heavier, it has more drainage problems, and it allows less oxygen to get to the plant roots. Those are some serious limitations.
While coco is packed with nutrients, it doesn’t have everything plants need to grow and thrive. Coco coir naturally contains potassium (K) and phosphorous (P), but it doesn’t have the amount of nitrogen (N) required by marijuana plants. That means growers must add nutrients to the medium to produce healthy plants.
Most growers who use soil also apply fertilizers, compost, or plant food. The fact that coco coir is a comparatively inert material isn’t necessarily a down-side. It gives growers a blank slate to start out with, so they’re better able to control the exact amount of macronutrients and micronutrients provided to their plants.
Coco coir is also comprised of a combination of one-third lignin, a material found in wood, and two-thirds complex carbohydrates, including the polysaccharides cellulose and hemicellulose. These carbohydrates provide a great breeding ground for microorganisms, which help to break down organic matter and make it more easily available to the plants.
The microorganisms that thrive in coco coir include rhizobacteria. These beneficial bacteria convert the cellulose found in coco fibers into carbon, which feeds both plants and other beneficial microorganisms. They also help to break down other types of organic matter.
Coco coir is naturally resistant to fungus and bacterial growth. This makes it a perfect fit for hydroponic setups. Unlike some organic materials, it doesn’t attract garden pests, so it’s just as good for outdoor container grows. Soil, in comparison, is known to harbor a variety of harmful microorganisms in addition to beneficial bacteria, which makes plants grown in garden soil more prone to pest infestations.
Coco coir naturally has a pH between 5.6 and 6.2, which is perfect for growing marijuana. Soil pH is much more variable and harder to control.
Coco Coir vs. Peat Moss
Coco coir is often compared to peat moss in terms of its role in marijuana growing, but it’s much more sustainable. It’s a 100% renewable resource. The average coconut tree produces around 150 coconuts per year, which means there’s always plenty of coco fiber to go around. In comparison, it takes 25 years or longer to regenerate a peat bog.
As previously mentioned, coco fiber can be reused up to three times. This is especially true in hydroponic grows where the coir can be flushed clean and reused immediately. After three uses, it begins to break down. At this point, it will be unsuitable as a growing medium, but it can be composted and used to feed other plants.
Types of Coco Coir
There are three types of coco coir available to commercial and hobby growers in North America. Growers can purchase coco fiber, pith, or chips. Each of these types of coir has benefits and drawbacks. Some growers prefer to use a mix of them, while others swear by using coco pith alone.
Coco Coir Pith
Coco coir pith has a rich, brown color and is similar in texture to peat moss. Coco pith retains water better than chips or fiber. Most growers don’t use pith alone, as it can create adverse conditions around the plant’s roots that lead to waterlogging. It’s best to mix 15 to 20% perlite into coco pith to improve drainage.
Coco Coir Fiber
Coco fiber has a stringier texture, which makes it perfect for oxygenating the root zone. It’s much less absorbent than pith, though. Mix it with pith or another substrate to improve water retention without sacrificing aeration.
Coco Coir Chips
Coco chips aren’t ground as finely as pith, and they aren’t as long as fiber bundles. These small chunks of coir retain water better than fiber but provide more air pockets in the plant’s root zones. Some experts feel that their larger size makes them impractical for growing cannabis, while others insist that adding coco chips to a blend of fiber and pith creates a perfect environment for their plants.
Coco Coir Mixes
Experienced growers typically create their own coco coir mixtures, often combining other organic and man-made grow media depending on the unique needs of their opertation. Those who are new to growing in coco might want to purchase pre-mixed products instead. Hydroponic growers should look for a coir mix designed for these systems, while soil-based growers looking to improve their yields should look for a mix designed with that purpose in mind.
Quality Coco Coir
Unprocessed coco coir is often high in sodium and chlorine since coconuts grow near the ocean. These must be washed and leached out of the material before it can be used to grow marijuana. When growers buy their coir from a respected supplier, they can trust that it has already been cleansed and leached and won’t have to waste the time and effort doing it themselves.
Nutrients for Coco Coir Growing
Since coco coir doesn’t have all the nutrients required to support healthy marijuana plants, growers must supplement it with specialized nutrient formulas. It’s best to purchase a nutrient formula specifically designed for use with coco coir, which already has significant amounts of potassium and phosphorous and trace amounts of many micronutrients.
When using coco coir in a hydroponic setup instead of mixing it with soil or other substrates, growers must purchase liquid nutrients designed specifically for hydroponic grows. These products are available both online and at specialty hydroponic gardening shops.
Experienced growers who use coco coir as a base and supplement it with other grow media sometimes make their own nutrient mixes, but this takes a lot of knowledge, plus some trial and error. Each ingredient in their media mixes imparts different macronutrients, micronutrients, and minerals, and providing for the marijuana plant’s nutrient needs is a fairly exact science. Unless you have a background in chemistry or a lot of experience with hands-on organic grows, it’s best to trust the experts and pay some extra money for a specialty product.
Does Coco Coir Produce Larger Yields?
When compared to standard soil or peat mixes, coco coir can produce substantially larger yields. This is especially true when it’s used by novice growers who might otherwise have trouble maintaining healthy moisture levels in soil-based grows. When they switch to coco from soil, growers can expect to see a 25% increase in their annual yields.
Growers will only see larger yields if they provide supplemental nutrients. Supplement the coir before planting, then pay careful attention during the seedling and early vegetative stages. Expect to see some signs of nutrient deficiency by around the fourth week of the vegetative stage and take action immediately if the leaves start to yellow or the plant’s growth slows down significantly.
Most growers who use coco coir follow pre-determined nutrient application schedules. Just follow the instructions offered by the liquid nutrient’s manufacturers the first season, then tweak them as needed to ensure that the plants have what they need to thrive without overdoing it and causing nutrient burn.
Coco Coir in Hydroponic Setups
Coco coir is one of the most popular grow media among hydroponic growers, but that doesn’t mean it’s completely problem-free. For one thing, coconuts are harvested from a wide variety of places, which can alter their pH and electrical conductivity (EC) values. Combined with the fact that this media also has a high cation exchange capacity, this makes it difficult to control total dissolved solids (TDS) levels.
The best way to deal with this problem is to purchase coco from producers that treat their products with calcium nitrate solutions to create a neutral medium. Growers can also ensure neutrality by treating their coco with a solution composed of 1 g/L of calcium nitrate mixed with distilled water, then following up by a treatment of 2 g/L of tetrasodium EDTA. Most growers find that the inconvenience of either purchasing treated coco or performing this process themselves is well worth the trade-offs.
Benefits of Coco Coir for Hydroponic Growers
When treated properly, coco coir is an almost perfect media for growing hydroponic marijuana. The right mix of pith, fiber, and chips will hold water well while simultaneously ensuring adequate aeration, and its fibrous structure is great for encouraging root growth.
Coco fiber’s ability to withstand substantial exposure to water and nutrient solutions without decomposing also contributes to this material’s popularity as a hydroponic medium. It can be rinsed and reused up to three times, which cuts back on costs, and there’s no need to worry about the grow medium decomposing and causing pH changes or other issues.
The fact that coco coir is known for producing increases in crop yields also appeals to commercial hydroponic growers, as does its affordability. Coco coir can also be mixed with other hydroponic grow media, including things like perlite and vermiculite to alter its ability to hold water depending on what type of setup growers use.
The Best of Both Worlds
When used as a replacement for soil, coco coir offers the best of traditional and hydroponic growing. Outdoor growers who would otherwise be stuck working exclusively with soil and various amendments can grow their marijuana plants in pots filled with coco coir to take advantage of its pest resistance, improved root zone oxygenation, water retention, and increased control over nutrients without having to invest in a full hydroponic setup. There are few commercial or hobby grow operations that won’t benefit from making the switch from soil to coco.
The Bottom Line
Coco coir is a natural, organic material that is equally useful in hydroponic setups and as a replacement for soil in traditional indoor and outdoor container grows. It takes a little extra work to grow with coco coir, but those who are willing to put in the effort will find that increased yields more than make up for the time it takes to supplement nutrients and check their levels throughout the season.
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