How to grow cannabis in coco coir for bigger, better yields

Not growing cannabis in coco coir? You could be missing out on bigger yields and healthier plants. 

Many growers struggle with soil-based cultivation, battling inconsistent watering, poor aeration, and nutrient deficiencies. 

This coco coir cannabis grow guide gives you a complete walkthrough of the fundamentals of how to grow cannabis in coco coir for optimal results. 

In this post, you’ll learn everything from choosing the right coco coir to watering techniques and nutrient management, ensuring you get thriving plants and impressive harvests. 

Let’s get started! 

Disclaimer: Any information given on this site is for educational purposes only. Please ensure if you’re growing cannabis, you’re doing so by the law and subject to appropriate permissions and licenses of the applicable country.  

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What is coco coir?

Coco coir or coconut coir is made from the fibrous husk of coconuts, a waste product or by product of the coconut industry.  

Coco has become an increasingly popular growing medium because it is peat-free, retains water well, and provides excellent oxygenation for healthy roots.

Growing with coco coir is a rewarding experience. 

It's essentially hydroponics, but you're also using a soil-like medium that still connects you with the earth compared to traditional hydroponics.

As a versatile growing medium, coco can be used alone or mixed with perlite to improve drainage.  It's also usually organic and can be reused.

Many growers use coconut coir because it is eco-friendly and peat-free, providing a sustainable alternative to peat moss. 

Because it’s an inert growing medium, it contains no natural nutrients, so you’ll need to add nutrition from day one.

It's generally more tricky to use than growing in soil, but the yields will be bigger in coco compared to soil.

These are the three main types of coco coir products:

• Coco peat – Fine-textured and highly water-retentive.
• Coco coir fibre – Coarse strands that improve aeration.
• Coco coir bricks – Dehydrated coco coir blocks that expand when hydrated. 

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Choosing the best coco coir for cannabis

Not all coco coir is the same. To ensure healthy plant growth, look for coco coir for cannabis that is low in salts, pre-buffered, and organic. 

Some growers prefer coco coir blocks, while others use pre-hydrated coco peat. When choosing your coco coir substrate, check for:

• Organic certification (avoid chemical treatments)
• Washed and buffered coco (prevents calcium/magnesium lockout)
• Medium to coarse texture (better drainage and root growth)

Preparing coco coir for growing cannabis

Before planting, coconut coir must be hydrated, buffered, and mixed with perlite for better drainage.Step-by-step preparation:

1. Hydrate your coir bricks by soaking them in water until fully expanded.
2. Buffer the medium with a Cal-Mag supplement to prevent deficiencies.
3. Mix with perlite (70% coco coir, 30% perlite) for better oxygenation.
4. Check pH levels (aim for 5.8–6.2) before planting.

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‍Stages of cannabis growth in coco coir

Starting cannabis seeds in coco coirTo ensure a strong root zone, start your cannabis seeds in a light and fine coco coir mix.

1. Use small pots with coco coir and perlite.
2. Pre-moisten the potting mix with pH-balanced water.
3. Plant seeds about 1cm deep.
4. Maintain warm temperatures (20–25°C) and high humidity (60–70%).
5. Keep the medium moist but not soaked until germination.

Seedling stage (Weeks 1–2)  

• Keep the coco coir lightly moist, but avoid overwatering.
• Use a weak nutrient solution (¼ strength) to prevent deficiencies.
• To encourage root development, maintain an 18–24°C temperature and 60–70% humidity. Read up on the optimal VPD for seedlings here.

Vegetative stage (Weeks 3–8)

• Increase watering frequency; coco coir holds water but drains well, so you may need daily feeding.
• Provide a balanced nutrient mix high in nitrogen to promote leafy growth.
• Keep humidity around 50–60% and temperatures at 22–26°C. More info here on the ideal VPD for veg.
• Train plants early for bigger plants and optimal light exposure.

Flowering stage (Weeks 9–16)

• Reduce nitrogen and increase phosphorus and potassium for strong bud development.
• Maintain humidity at 40–50% to prevent mould and root rot. Check out our post on the best VPD for flower here.
• Water your plants consistently and check for salt buildup in the root zone.

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Growing cannabis in coco coir: The key to bigger yields

‍Unlike soil, growing in coconut coir allows for high-frequency fertigation, meaning you can water your plants up to 15 times a day without overwatering.  

‍This results in bigger plants with vigorous root health.

Why coco coir boosts yields:

• Holds water while maintaining high aeration.
• Encourages healthy root development.
• Allows high-frequency fertigation for faster growth.
• Provides complete control over nutrient levels.

Watering and nutrient management in coco coir

Watering in coco coir

‍Proper watering is essential for healthy roots when growing in coco coir. Coco also has a high air pocket ratio, so, unlike soil, coco coir retains moisture while allowing for excellent air exposure, making it difficult to overwater.However, if excess water can’t drain, root rot can occur.

• Water frequently, at least once daily, to prevent dry pockets in the root zone.
• Ensure your pots allow for proper drainage, preventing nutrient buildup.
• Since coco is inert, you must add nutrients from the start.
• Consider using coir bricks, which expand when hydrated and improve root health.
• Avoid letting the bricks dry out completely, as coco coir is designed to stay slightly moist for optimal plant health.

Since coco coir is highly water-retentive, it supports bigger plants, making it a versatile growing medium. 

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Nutrient management in coco coir 

Since coco coir is inert, it lacks natural organic matter and requires consistent feeding like traditional hydroponics.

‍Without the right nutrient quantities, cannabis may experience deficiencies in calcium, magnesium, and other essential minerals.‍

• Use a coco-specific nutrient formula to maintain proper levels.
• Keep pH between 5.8 and 6.2 for optimal root development.
• Supplement with Cal-Mag to prevent calcium and magnesium deficiencies, which are common in coco peat.
• Flush the medium regularly to remove excess salts, ensuring a balanced nutrient uptake.

Many growers prefer coco coir for their gardening uses, as it allows better control over nutrients compared to traditional potting soil.  

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Choosing the right containers for a coco coir grow

Selecting the correct container is crucial for maintaining healthy roots and maximising yields when growing cannabis in coco coir. 

‍Fabric pots are the top choice for cannabis growers because they enhance aeration, prevent root rot, and encourage root growth through air pruning. This means roots grow stronger without becoming root-bound. 

• The water-retaining properties of pots made of fabric prevent excessive drying while maintaining a good water drain.
• Bigger plants thrive in fabric pots, as they provide better airflow to the root zone.
• Smaller containers (1–3 litres) are fine for seedlings, but for full-grown cannabis, 10-litre pots or larger are best.

If you’re planning a cannabis grow using coco fibres, avoid plastic pots, as they can hold too much moisture and lead to root rot.  

Instead, pots made of fabric combined with perlite in your coco peat mix create the perfect environment for healthy roots and larger plants.   

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Preventing common issues in coco coir growing

Avoiding root rot for healthy root development

One of the biggest risks when growing in coco coir is root rot, which can stunt growth and cause poor root health. Maintaining proper aeration and drainage is crucial to ensure healthy roots.

• Use well-draining pots made of fabric to promote oxygen flow in the root zone and prevent waterlogging.
• Mix perlite into your coco peat to improve aeration and avoid compacting the medium.
• Never let water sit at the bottom of your pots - ensure your coco coir allows proper water drain.
• Check roots regularly; healthy roots should be white and strong, not brown or slimy.

Managing pH and nutrient deficiencies

Because coco coir is inert, it holds onto nutrients but lacks natural organic matter. 

‍If not appropriately managed, coco coir products can accumulate salts, leading to nutrient lockout.‍

• Flush regularly to remove excess salts and maintain optimal nutrient levels.
• Always buffer coco before use to prevent deficiencies in calcium and magnesium.
• Keep pH levels between 5.8 and 6.2 for consistent nutrient uptake.

Recognising overwatering vs. underwatering

• Overwatering: If leaves are droopy and the medium feels wet, you’re overwatering. Reduce the frequency and allow better drainage.
• Underwatering: If leaves are wilting and the medium is dry, increase watering to maintain consistent moisture. 

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Takeaways

Growing in coco might take some time to master, but the rewards are massive once you get the hang of it. 

‍The combination of high aeration, the ability to water frequently, and complete control over nutrients will ensure your cannabis plants produce bigger and better yields.

‍Since coco coir is an eco-friendly, renewable resource, it’s also a sustainable way to grow. 

Whether you’re a beginner or an experienced cannabis grower, switching to coco coir could be the upgrade your grow needs.

Happy growing!

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FAQs

Is coco coir good to grow cannabis?

‍Absolutely! Coco coir is one of the best mediums for growing cannabis because of its light texture and water-retentive properties. 

‍Unlike traditional potting mix, coco peat allows for frequent watering without the risk of overwatering. 

Its inert growing medium nature means you have full control over nutrient quantities, enabling you to positively influence plant growth. 

Some growers prefer coco coir products as a peat-free, eco-friendly alternative that supports larger plants and higher yields. 

Used in hydroponic grow systems, it enhances root health and helps cannabis plants flourish.

Can you mix coco coir with soil?

‍Yes, coco coir can be mixed with soil to enhance aeration, improve water-retaining properties, and support healthy roots. 

‍Combining coco coir products with potting soil creates a peat-free, eco-friendly blend that retains moisture while preventing compaction.

Adding perlite to the mix further boosts root growth and drainage. 

However, since coco is an inert growing medium, you’ll need to add nutrients to maintain proper levels of nutrients. 

Some growers use a coco-soil mix for gardening uses, especially when growing plants that do well in well-aerated, water-retentive environments.

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Do plants grow faster in coco coir?

‍Yes, many plants can experience accelerated growth in coco coir compared to traditional soil. 

‍This is because of coco coir's excellent aeration and water retention properties, which promote robust roots. 

Additionally, coco coir's neutral pH allows for precise nutrient management, further supporting healthy development. 

Therefore, with proper nutrient supplementation, plants often grow faster in coco coir than in soil.  

Can you overwater cannabis in coco coir?

‍While coco coir is renowned for its excellent water retention and aeration properties, overwatering can still pose challenges.

‍Excessive watering without proper drainage can lead to waterlogged conditions, depriving roots of necessary oxygen and potentially causing issues like root rot. 

Ensure that your growing setup allows for adequate drainage and that moisture levels are monitored closely with a moisture probe.

A consistent watering schedule tailored to your plants' needs can help prevent overwatering and promote healthy growth.  

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