In short: Use the rule-of-thumb: 1 litre of hydrated coco coir per 1 litre of container/bed volume. One 5 kg buffered coco coir brick expands to roughly 75 litres. So a 60 litre raised bed needs ~0.8 of a brick; a 1 m × 1 m bed at 8 cm depth needs ~1 brick. Use the on-site calculator for precise figures.
One 5kg Blue Apple Garden coco coir brick expands to approximately 75 litres when fully hydrated. A 15kg 3-pack expands to approximately 225 litres. Use the coverage tables below to calculate how much you need for your specific setup.
How Coco Coir Volume Is Measured
Coco Coir is sold as compressed dry bricks. The volume stated on the pack refers to the expanded volume after adding water — not the brick size itself. Always use expanded volume for your calculations.
- 1 × 5kg brick = ~75 litres expanded
- 3 × 5kg bricks (15kg pack) = ~225 litres expanded
Coverage by Container Type
| Container | Volume (litres) | Bricks needed (5kg) |
|---|---|---|
| Small pot (15cm diameter) | 2–3L | 1 brick fills ~25–30 pots |
| Medium pot (25cm diameter) | 8–10L | 1 brick fills ~7–9 pots |
| Large pot (30cm diameter) | 15–20L | 1 brick fills ~4–5 pots |
| Very large pot (40cm+) | 30–40L | 1 brick fills ~2 pots |
| Standard grow bag | 25–35L | 1 brick fills ~2 grow bags |
| XL grow bag / trough | 50–75L | 1 brick per bag |
Coverage for Raised Beds
For a raised bed, calculate the volume as: length (cm) × width (cm) × depth (cm) ÷ 1000 = litres needed.
| Raised bed size | Fill depth | Volume needed | 5kg bricks |
|---|---|---|---|
| 60cm × 90cm | 20cm | 108L | ~2 |
| 90cm × 120cm | 20cm | 216L | ~3 |
| 120cm × 240cm | 20cm | 576L | ~8 |
| 120cm × 240cm | 30cm | 864L | ~12 |
Note: Most raised beds are not filled to 100% coco coir. A typical mix is 50% coco coir + 30% compost + 20% perlite. Adjust the quantity accordingly — e.g. for a 216L raised bed using 50% coco coir, you need approximately 108L = 1.5 bricks (~2 bricks with a small reserve).
Coverage for Greenhouse Grow Bags
For a standard UK greenhouse season growing tomatoes or peppers in grow bags, the typical allowance is 35–50 litres per plant. One 5kg brick (75L) provides enough for 1–2 plants in bag culture. For a 3m × 6m greenhouse with 12 tomato plants, you would need approximately 6 bricks (450L).
Water Required for Expansion
| Quantity | Water needed | Expanded volume |
|---|---|---|
| 1 × 5kg brick | 20 litres | ~75 litres |
| 3 × 5kg bricks (15kg pack) | 60 litres | ~225 litres |
How to Calculate Your Exact Requirement
- List all containers, pots, or beds you plan to fill
- Calculate the volume of each (length × width × depth ÷ 1000 for litres)
- Multiply by the percentage of the mix that is coco coir (e.g. 70% = × 0.7)
- Total the volumes and divide by 75 to get the number of 5kg bricks required
- Add 10% contingency — coco coir is inexpensive and it is better to have too much than too little
Is It Cheaper to Buy in Bulk?
The 15kg 3-pack (3 × 5kg bricks) offers better value per litre than buying individual 5kg bricks. For large gardens, allotments, or a full greenhouse season, the 3-pack is the more cost-effective option. See our bulk buying guide for UK growers for more detail.
Frequently Asked Questions
How many litres does a 5kg coco coir brick expand to?
A 5kg Blue Apple Garden coco coir brick expands to approximately 75 litres when fully hydrated with 20 litres of water.
How much coco coir do I need for a raised bed?
Calculate the bed's volume (length × width × depth in cm ÷ 1000 = litres). If filling with 50% coco coir, halve that figure and divide by 75 to get the number of 5kg bricks required. For a typical 90cm × 120cm × 20cm raised bed: ~216L total, ~108L coco coir = 1.5 bricks (buy 2).
How much coco coir do I need per plant?
As a general guide: small herbs and seedlings need 2–5 litres; medium vegetables (lettuce, courgette) 10–15 litres; large crops (tomatoes, peppers) 25–50 litres per plant in a container system.
How much water do I need to expand coco coir?
20 litres of clean water per 5kg brick. Allow 20–30 minutes for full expansion. Break up any remaining clumps before use.
How long does one 5kg brick last?
For a typical UK container garden (4–6 large pots or a small greenhouse), one 5kg brick provides enough medium for one full growing season. If reusing and refreshing the medium between crops, the same brick can last 2–3 seasons.
Shop Coco Coir
Available as a 5kg brick (expands to ~75L) or a 15kg 3-pack (expands to ~225L). Free UK delivery on all orders.
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