Growing Cannabis Seeds in Coco Coir: Benefits & Drawbacks

Growing cannabis seeds in coco coir provides a number of advantages; however, there are a few drawbacks as well. Coco coir is a renewable source of soil-less substrate growing medium, made from the coconut husk fibers. This type of grow medium can provide the ideal environment for developing cannabis crops. One of the benefits of growing cannabis in coco coir is the efficient use of nutrients available. Due to its porous structure, coco coir allows nutrients to become readily available for the plant’s roots, without becoming water-logged. This makes coco coir an ideal choice in humid climates where it’s difficult to control water levels. Cannabis plants also benefit from coco coir’s ability to maintain air porosity around the roots, allowing air to move freely through the substrate. This lets the plants get an optimal amount of oxygen even during periods of high humidity.

Along with the advantages, there are a few drawbacks associated with growing cannabis in coco coir. It is often difficult to maintain pH levels, as coco coir absorbs nitrogen at a high rate, leading to an increase in pH levels over time. It can also become overly dry as coco coir is known to absorb water easily and quickly. Plant roots may suffer if the coir is allowed to become too dry. Lastly, coco coir may contain bacteria, fungi, and other parasitic organisms which can be damaging for cannabis plants; for this reason, coco coir should always be prewashed and sterilized before use.

pH and Salinity Control

Since coco coir absorbs high levels of nitrogen, controlling the pH and salinity levels becomes an important factor when cultivating cannabis. One thing to note is that the type of coco coir used plays an important role in this regard. For instance, coco coir that is labeled ’buffered’, as opposed to ‘unwashed’ or ‘unbuffered’, is usually processed with off-the-shelf fertilizers, which keeps the pH and salinity at a low and stable level for longer. To maintain optimal conditions for the cannabis plants, pH levels should be checked and adjusted on a regular basis. This can be done by adding hydroponic pH adjusters to the nutrient solution or coco coir itself.

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Aside from pH and salinity, cannabis grown in coco coir can also require additional nutrients that are not found in traditional soil mixes. Adding coco-specific nutrient formulations can prove to be beneficial, especially when the nutrients are formulated to work in tandem with coco coir. This will ensure that the cannabis plants are able to absorb the much-needed nutrients and minerals they need in order to properly grow and mature. Additionally, adding a microbial additive to the coco coir can help to Strengthen the root system and promote strong growth.

Best Practices

When using coco coir for cannabis cultivation, it is important to follow the best practices for optimal results. It is crucial to pre-soak the coco coir prior to adding it to the nutrient solution, as this will ensure that the correct moisture content is present. Likewise, mixing in one part perlite along with the coco coir is a reliable way to provide adequate aeration, as perlite has excellent draining and aeration properties. Looking after the roots is also an important step – cannabis plants with healthy roots will generally show positive results when growing with coco coir.

Since coco coir is known to absorb water rapidly, it is important to water the plants regularly. Plants should be watered every other day, with nutrient-rich water, to keep the coco coir hydrated and the roots healthy. It is best to avoid over-watering, as this can lead to root rot and other health-related issues. As with any other growing medium, it is also essential to keep an eye on pH and salinity levels, regularly checking for any fluctuations or abnormalities.

Sterilising Coco Coir

While it is a relatively clean medium, coco coir is known to contain fungal spores, bacteria, and other parasitic organisms. For this reason, it should be sterilized before use. This can be done in a number of ways, such as boiling, steaming, or soaking the coco coir in a diluted hydrogen peroxide solution. Once sterilized, the coco coir should be properly drained, as any excess water will increase humidity levels, making it difficult to maintain optimal environmental conditions.

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Another thing to keep in mind when sterilizing coco coir is that additional nutrients or fertilizer should not be mixed in until after the coco coir is sterilized, as high heat levels can break down those components. Finally, it is important to be aware of the temperature and duration of the sterilization process, as coco coir tends to absorb heat quickly, and can be damaged or destroyed if left in high heat for too long.

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Natural Bacteria

Aside from sterilizing, cannabis growers may also choose to employ natural bacteria to help promote healthy growth. Natural bacteria are beneficial because they provide the plant with essential nutrients, improve overall root development, and help to introduce beneficial fertility elements. Adding beneficial bacteria to the coco coir should be done shortly before adding nutrient solution, as natural bacteria will require the presence of some nutrients in order to survive and produce fertilizing elements.

These helpful bacteria can also help to control and manage the coco coir’s moisture content. Natural bacteria are efficient at absorbing and regulating moisture levels, as well as reducing any odors that may come from the coco coir. At the same time, they increase beneficial oxygen levels in the substrate, allowing the roots to breathe better and take in more nutrients from the coco coir.


The type of nutrient solution used has a significant impact on the overall health and yields of cannabis plants grown in coco coir. Coco-specific nutrient solutions are typically lightweight, offering a balanced range of macro and micro nutrients that are well-suited for nutrient-rich coco coir. In addition, if the coco coir has been sterilized, it is important to provide fertilizers that contain beneficial bacteria. This type of solution will introduce beneficial bacteria into the coco coir to help with nutrient absorption, root development, and oxygen levels.

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When feeding, it is important to monitor the level of nutrients in the solution, as the coco coir can absorb and retain high levels of nutrients over time. Additionally, the temperature of the solution should be checked regularly to ensure that it is within a suitable range – ideally between 68 and 72° Fahrenheit. Too low of a temperature may slow down nutrient absorption, while too high of a temperature can lead to nutrient burn in the coco coir.

Reducing Wastage

Finally, coco coir can be a surprisingly sustainable medium for cannabis cultivation. During the flowering phase, it is highly recommended to flush the coco coir regularly to ensure that it does not become toxic due to a build-up of unused nutrients. This will help to reduce nutrient waste and also increase the overall quality of the crop. Additionally, spent coco coir can be reused as a soil amendment, by mixing it into the soil or compost pile for future use.

In conclusion, growing cannabis in coco coir can provide a great number of benefits. It can provide an optimal growing environment along with efficient nutrient use, and can also help to reduce wastage. However, the grower should be aware of the potential drawbacks associated with this type of substrate, such as difficult pH and salinity control and the potential of containing harmful organisms, and take the necessary steps to counter these issues. With proper understanding and management, cannabis growers can get the most out of coco coir when cultivating cannabis.

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