In short: Top questions UK gardeners ask about coco coir: how much does one 5 kg brick make (75 L), what's the pH (5.5–6.5 buffered), is it peat-free (yes), do I need to buffer it myself (no, ours is pre-buffered), can I use it alone (yes for some plants, blend with compost for most), and does it need extra fertiliser (yes — coir holds little nutrient).
15 Expert Answers to the Most-Asked Questions About Coco Coir
We have compiled the 15 questions our customers ask most frequently about coco coir — and answered each one with precision. Whether you are new to coco coir or an experienced grower troubleshooting a problem, this reference guide has you covered.
1. What exactly is coco coir?
Coco Coir (also called coir pith) is the fine, spongy material extracted from coconut husks after the long fibres have been removed. It is a by-product of the coconut industry and an excellent peat-free growing medium. It is compressed into bricks for storage and transport, then expanded with water before use.
2. What is the difference between buffered and unbuffered coco coir?
Raw (unbuffered) coco coir contains naturally occurring potassium and sodium salts that can compete with calcium and magnesium at root uptake sites — causing nutrient deficiencies even when nutrients are present in the feed. Buffered coco coir has been pre-soaked in a calcium-magnesium solution to displace these competing ions. It is ready to use without pre-flushing. Always buy buffered. Full comparison here →
3. What pH is coco coir?
Coco Coir has a natural pH of 5.5–6.5, which sits within the optimal range for most garden plants (6.0–7.0). This makes it considerably more plant-friendly than peat moss (pH 3.5–4.5) and more stable than many compost-based mixes.
4. What is EC and why does it matter in coco coir?
EC (Electrical Conductivity) measures the concentration of dissolved salts in a growing medium or solution. High EC in raw coco coir indicates excessive sodium or potassium that can stress plants. Buffered coco coir from Blue Apple Garden has an EC of ≤0.5 mS/cm, which is safely low. Anything above 1.5 mS/cm in the substrate is potentially harmful to sensitive plants. More on EC testing →
5. Does coco coir contain nutrients?
Coco Coir contains trace levels of potassium and phosphorus but is not a significant nutrient source. It functions as a structural medium, not a fertiliser. Plants grown in coco coir require a complete liquid nutrient programme from approximately week 2 onwards. This is actually an advantage — it gives you precise control over what your plants receive.
6. Can I reuse coco coir?
Yes. Coco Coir typically lasts 2–3 growing cycles before its structure degrades. Between cycles: remove spent root matter, flush thoroughly with clean water to reduce EC, check pH, and optionally re-buffer with a calcium-magnesium solution. Discard when it becomes compacted and no longer drains freely. Full reuse guide →
7. How much water does coco coir hold?
Coco Coir can hold up to 10 times its own weight in water while maintaining significant air porosity (22–30%). This combination — high water retention plus good oxygen levels — is what makes it so effective for roots. By comparison, garden soil typically holds 2–4× its weight and has much lower air porosity when wet.
8. How do I expand a coco coir brick?
Place the brick in a large container. Add warm water gradually — approximately 3–4 litres per kg of brick weight. The brick will begin expanding immediately and reach full volume within 20–30 minutes. For a 5 kg Blue Apple Garden brick, expect approximately 75 litres of expanded medium. Break up any clumps with a trowel or by hand before use.
9. Can I use coco coir in my garden beds?
Yes, though it works best blended with compost or soil. A 30–50% coco coir blend in raised beds improves drainage and water retention significantly. Pure coco coir in open garden beds provides no nutrients and may dry out faster than in containers. Add compost to supply organic matter and biology.
10. Is coco coir suitable for hydroponics?
Yes — coco coir is one of the most popular hydroponic substrates worldwide. It works particularly well in hand-watered drip systems and Dutch Bucket systems for tomatoes, cucumbers, and peppers. Its water retention is higher than rockwool, making it slightly more forgiving of missed waterings. Use coco-specific nutrients (with elevated calcium and magnesium) to compensate for the medium's natural cation exchange properties. Hydroponics guide →
11. What is the difference between coco coir and coco coir?
"Coco coir" is the umbrella term for all products derived from coconut husks. This includes coco coir (fine pith), coco fibre (long strands), and coco chips (chunky pieces). When most products are labelled "coco coir" in garden retail, they typically mean coco coir. The terms are often used interchangeably.
12. How does coco coir compare to perlite?
Perlite is an inert volcanic glass used primarily to improve aeration and drainage — it holds very little water. Coco Coir holds significantly more water and provides a better root environment for most plants. The two are often blended together: 70–80% coco coir + 20–30% perlite is an excellent all-purpose container mix with both moisture retention and drainage.
13. Is coco coir safe for organic growing?
Coco Coir itself is an organic, natural material. However, "organic growing" certification depends on the nutrients you use alongside it. The medium is inert and does not introduce synthetic chemicals. Some organic certifications (e.g. Soil Association) permit coco coir as a growing substrate.
14. Can coco coir go mouldy?
White mould on coco coir surface is typically saprophytic fungi — harmless decomposers that feed on organic material. It usually appears when the surface remains wet and airflow is poor. It is not harmful to plants. Improve airflow, allow the surface to dry slightly between waterings, and it will disappear. Root rot (from Pythium or Fusarium) is a more serious issue caused by overwatering, not by coco coir itself.
15. Where is Blue Apple Garden's coco coir from?
Our coco coir bricks are sourced from responsible producers in South Asia. They are fully buffered, low-EC tested, compressed for minimal transport impact, and arrive in recyclable packaging. All products are peat-free and compliant with UK horticulture standards.