Guide to Coconut Substrates

Coconut substrate is a modern growing medium made from fibers and husks of coconuts, available in many forms and suitable for a wide range of horticultural techniques, from traditional pot cultivation to hydroponics and large irrigation systems. In this guide we will help you choose the right type of coconut substrate for your grow room, garden, or greenhouse.

Coconut substrates are among the most versatile and easiest growing media you can choose for cultivation. Compared to soil, where it is difficult to have precise control over pH and nutrients in the medium, coconut makes it simple to monitor these two variables with EC and pH meters and adjust them using a nutrient solution. At the same time, coconut substrates have sufficient buffering capacity and retain water and nutrients well, so they are not as sensitive to mistakes as fully hydroponic systems. This gives you the best of both worlds: the security of a classic growing medium and the speed and efficiency of hydroponic growing.

MAIN ADVANTAGES OF GROWING IN COCONUT

• pH- and nutrient-neutral: Coconut fibers themselves contain minimal nutrients, which makes precise plant feeding easier. You can supply plants with exactly the nutrients they need at any given time. It is also simple to adjust the pH in the root zone area without increasing EC.
• Optimal drainage: Coconut fibers can hold up to ten times their weight in water and, unlike materials such as expanded clay or perlite that drain water quickly, they keep the plant root system moist for longer, so plants do not need to be watered too often. Compared to soil, water drains faster, allowing you to water and feed plants much more frequently.
• Healthy root development: Growing in coconut substrate is very beneficial for plant roots, which grow faster and are healthier. This is due to the fibers' ability to retain high amounts of nutrients, water, and air. Roots deprived of air (for example in overly compacted soil or poorly aerated hydroponic solution) tend to be poorly developed and susceptible to fungal attack.
• Fewer pests: Many soil insect pests and pathogens do not thrive in coconut. Additionally, coconut fibers often contain strains of Trichoderma that protect plant roots from other parasitic microorganisms.
• Ecological and reusable material: Coconut substrates are made from waste materials and can be reused. This represents a significant reduction in the carbon and environmental footprint of cultivation.

Buffered or unbuffered coconut

When choosing a coconut substrate it is very important to distinguish between buffered and unbuffered coconut. Buffering is the process of preparing coconut fibers before use for plant cultivation. Raw coconut fibers contain high amounts of salts and are poor in calcium and magnesium. During buffering, which involves soaking and rinsing in water with adjusted pH, the potassium and sodium ions bound to the coconut are replaced by calcium and magnesium, which plants need.

Most manufacturers supply pre-buffered coconut mixes that do not require further treatment before use — they only need to be soaked in water or nutrient solution. If you want to use coconut as an amendment to soil that is rich in nutrients and organic matter, it is not necessary to buffer the material in advance, because the substrate will still contain sufficient calcium and magnesium.

Types of coconut substrates and their uses

Pure coconut substrates

Coconut substrates without additives contain only coconut fibers and chips and are suitable as a base substrate for indoor and outdoor cultivation, in pots or hydroponically and when using automatic irrigation systems. Coconut substrates contain minimal nutrients and these must be supplied to plants in the form of fertilizers for growing in coconut substrate. Coconut fibers are also a great amendment to garden substrates, where they improve water and air circulation.

Coconut substrates with perlite/expanded clay

Coconut substrates enriched with perlite or expanded clay have better drainage properties and help prevent overwatering, which is especially useful for growers in pots. The typical ratio of coconut fiber to mineral component in such cases is usually 70% to 30%. Because the growing medium dries faster, it will be possible to water plants more frequently.

Compressed coconut substrates

Compressed coconut pressed into solid briquettes or blocks has the advantage of reducing storage and shipping costs. This is beneficial not only for retailers but also for large growers who need large quantities of growing medium. Compressed coconut substrate must be soaked in water or a buffering solution before use so the fibers expand. Afterwards it can be used pure or mixed with other additives such as peat, soil, or perlite/expanded clay.

Growing mats made from coconut substrate

Growing mats with coconut substrate are especially practical for growers using automatic irrigation systems, where they help save water and fertilizers thanks to precise and even irrigation. Despite their ability to retain large amounts of water, growing mats provide sufficient drainage and air access, which supports rapid root growth without the risk of pathogens or molds. Growing mats can be reused.

Coconut substrates with Trichoderma

Some ranges of coconut substrates contain Trichoderma, a naturally occurring beneficial fungus that can adapt to almost any environment. Trichoderma species produce metabolites that inhibit the growth of other microorganisms, thereby protecting plants from parasitic fungi and other pathogens. Some Trichoderma species (T. reesei) produce high amounts of cellulase, others (T. virens) are excellent mycoparasites and can parasitize other fungi, and others (T. harzianum) have proven effective in combating nematodes.

Grow bags with coconut substrate

Grow bags with coconut substrate ready to use are appreciated especially by greenhouse and outdoor growers. The advantage is easy use without the need to soak or buffer the coconut fibers. The coconut substrate in the bags is not compressed, so it allows good drainage and absorbs water well. Grow bags can be reused.

Like any growing medium, coconut has its challenges and requires certain knowledge and practice. Now that you know which type of coconut substrate to choose and how to use it, you are ready to start growing.