A 650 g coco peat briquette is a brick of compressed coir pith about 20 x 10 x 5 cm. Drop it in a tub with 3.5 to 5 litres of warm water, give it 10 to 30 minutes, break it apart with your hands and you have roughly 8 to 9 litres of loose, damp growing medium ready for seed trays. That's the whole process. The rest of this page is about getting it right for propagation, where seedlings are fussier than any other crop stage about salts, moisture and texture.
Briquette, block or disc: what's the difference?
All three are the same material, coir pith, pressed to a different size for a different job.
| Format | Dry size and weight | Expanded volume | Water to hydrate | Best for |
|---|---|---|---|---|
| Briquette | about 20 x 10 x 5 cm, 550–700 g (sold as 600 g or 650 g) | 6.5–10 L, most often quoted as 8–9 L | 3–5 L | Seed trays, small batches, retail packs, trials |
| 5 kg block | about 30 x 30 x 12 cm | 60–75 L realistic, 50–100 L quoted | 20–30 L | Potting-mix production, filling many trays at once |
| Disc or pellet | 30–100 mm across, 5–25 mm thick | 5–7 times its dry volume | A cup or two per disc | One plant per cell, no tray filling |
The briquette sits in the middle. It's the biggest piece of coir one person can hydrate in an ordinary bucket without a mixer, and the smallest unit that still fills several trays. Hydrating a block is a different job with different equipment, covered in the coco peat blocks guide. Discs and plugs are covered in the guide to coir discs and propagation plugs.
How much water, and how many litres do you get?
Labels and guides don't agree, so here's the spread you'll see for a 650 g briquette.
| Figure | What's quoted |
|---|---|
| Water to add | 2 L (one Indian seller), 3 L per brick, 3.25 L, 3.5–4 L, 4–5 L warm water |
| Expanded volume | 6.5 L, 8 L, 8–9 L, 9 L, 9–10 L, 9–11 L |
| Time to expand | 5–10 minutes, 15–30 minutes, 15–45 minutes, up to 8–12 hours |
| Per kilogram of compressed coir | roughly 10–14 L, against 9–17 L/kg quoted for blocks |
Why the range? Briquette weight varies between 550 and 700 g because pressing moisture and density differ from run to run. Fine, dusty pith packs denser and expands less than pith with some short fibre in it. And "litres" depends on whether the wet coir was measured loose or settled. The honest expectation is 8 to 9 litres of loosely filled medium, and you'll know your own figure after one batch.
On water, the lower figures only work if you add in stages. A brick left overnight in 3 litres can still have a dry core. Start with 3.5 to 4 litres, warm if you have it, wait, break it up, then add a few hundred millilitres at a time until nothing dry remains. For a seed tray you want damp, not dripping, so stopping short and adding is better than drowning it and then draining.
Preparing a briquette for seedling trays and plugs
1. Hydrate in a clean container
Use a bucket or tub with at least 10 litres of room. Hydrate the brick whole. A dry briquette is too dense to break by hand, and chipping pieces off leaves hard lumps that wet unevenly. Use irrigation or mains water, never recycled drainage. Seedlings have no reserves to cope with whatever is in your runoff.
2. Fluff it completely
Once the brick has slumped, work through the whole mass with your hands or a clean trowel until it's evenly crumbly with no lumps. A compressed lump in a tray becomes a dry pocket that roots can't enter and that won't rewet from above. This is the step people rush, and it shows up two weeks later as patchy germination.
3. Drain to damp
Squeeze a handful. A few drops should come out, not a stream. If you've overshot, tip the coir into a tray with drainage holes and let it stand until it stops pooling, or fold in some dry coir from another brick. Saturated coir is colder and holds less air, both of which slow germination and encourage rot in the first week.
4. Sieve out coarse fibre if you're filling small cells
Briquette coir usually contains some short fibre and the odd chip. In a 50- or 72-cell tray this doesn't matter. In a 288 plug tray it does, because a single long fibre can bridge a cell and leave an air gap under the seed. A garden sieve or 6 mm mesh takes the fibre out in a couple of minutes. Keep the siftings for coarser blends or as a loose cover for larger seed. If you'd rather not sieve, ask for a fine or screened grade when you order. The briquette product page lists what can be specified.
5. Blend after hydrating, not before
If you're adding perlite or vermiculite, do it to the wet, fluffed coir so your volumes are right. Dry coir expands and throws the ratio off. Ratios in use for propagation run from straight fine coir for plug trays and cuttings, through 70 % coir, 20 % perlite, 10 % vermiculite for ornamental plugs, to 2 parts coir, 1 perlite, 1 vermiculite for general seed starting. Match the perlite grade to the cell size, fine for small plugs and coarse for larger cells and cutting beds. The reasoning and more ratios are in the guide to coir, perlite and vermiculite mixes.
EC and pH for propagation, and when to rinse
Seedlings tolerate about half the salt level of an established crop. The figures you'll come across are injury in young plants around 3.0 dS/m by saturated extract, medium pH of 5.5 to 6.0 or 5.5 to 6.5 depending on the guide, and a rooted-plug target around 1.5 mS/cm once feeding starts. For the raw coir before sowing, the thresholds are simpler.
Test a handful of the hydrated coir in 1.5 or 2 parts distilled water, stand it 30 minutes, and read.
- Below about 0.5–0.7 mS/cm: fill trays as it is.
- 0.7 to 1.0 mS/cm: fine for blending or large-seeded crops, or rinse once.
- Above 1.0 mS/cm: rinse before sowing.
A rinse is just a second soak. Flood the fluffed coir with fresh water, stir, let it settle, pour or drain off, and squeeze back to damp. One rinse removes most of the loose salt. Washed coir, which is how CVM Fiber and Industries processes its pith in Kanyakumari, Tamil Nadu, India, usually arrives under the threshold and goes straight into trays. The pith is washed with water only, to reduce EC, with no calcium nitrate or other chemicals added, so it is not buffered. What buffering is and when it matters is explained in buffered vs unbuffered coco peat. The short version for propagation: unbuffered washed coir works for germination, and you start light calcium-and-magnesium-containing feed once true leaves appear.
One warning on testing plugs after sowing. Single cells hold too little medium for a standard test, so if you need to check a tray mid-crop, pool the medium from at least 20 cells before extracting.
Filling trays and compaction
Fill loosely. Scoop the damp coir over the tray, sweep it level with a straight edge, then tap the tray once on the bench to settle it. Don't press it into the cells with your fingers or stack filled trays on top of each other. Coir filled wet and pressed firm loses its air space, and the cell stays waterlogged for weeks because there's nothing to drain through. Loose filling followed by the first watering gives the right density on its own.
Dibble the seed hole rather than pushing the seed in, and cover with a thin layer of fine coir or vermiculite. Very fine seed goes on the surface uncovered.
How many trays does a briquette fill? Sellers claim anywhere from three to six standard 1020 trays per brick, and the spread is entirely about tray depth. Shallow 1020 flats take the higher count, deep plug trays the lower. Fill one tray from a measured jug and multiply.
Watering young seedlings in coir
Coir holds a lot of water, so the risk in the first fortnight is overwatering, not drying out. Water from a fine rose or by capillary mat, lightly, and let the surface go from dark to light brown between waterings. Lift the tray. Weight tells you more than the surface colour. Coir dries from the top, and the surface can look dry while the bottom of the plug is still saturated.
Once coir dries hard it resists wetting for a while and water runs off into the gaps between cells. If that happens, bottom-water the tray for a few minutes rather than pouring from above. Feeding starts at true leaves, at a quarter to half of your normal strength, and the detail is in the guide to coco peat for seed germination.
Storing opened briquettes and leftover coir
A dry, unopened briquette keeps for years if it stays dry. Store it off the floor, out of the sun and in its wrapper, because the pith absorbs humidity and a damp brick goes mouldy inside its own packaging.
Hydrated coir is a living medium, so use it within two or three weeks. Keep it in a lidded tub out of direct sun and don't let it dry to a crust. If it smells sour or grows white mould, don't put it under seedlings. Compost it or use it in beds.
When briquettes make sense versus blocks
For a nursery the decision is about labour and batch size, not quality. The coir inside a briquette and a block from the same factory is the same pith.
Briquettes suit you when:
- You fill a few trays at a time and want to hydrate exactly what you'll use that day. No half-hydrated block sitting in a tub.
- One person is doing the work with a bucket, not a mixer or a hydration bay.
- You run trials and want to compare batches or suppliers in equal portions.
- You retail. A 650 g brick fits in a carrier bag and on a shelf, and the customer can hydrate it in a kitchen bucket. A 5 kg block does neither.
- You ship small quantities. Briquettes case-pack neatly and don't need a pallet.
Blocks suit you when you're filling pallets of trays a day, producing potting mix in volume, or buying by the container, where price per litre matters most. Many nurseries end up with both: blocks for the production line and a few cartons of briquettes for the propagation bench, where small, exact batches make life easier.
If you're a retailer or a nursery weighing briquettes against blocks, get in touch with your tray sizes and weekly volumes and we'll help you work out what fits.
FAQ
How much water does a 650 g coco peat briquette need?
Start with 3.5 to 4 litres of warm water and let it stand. Break the brick apart, then add a few hundred millilitres at a time until no dry pockets remain. Most people end up between 3.5 and 5 litres. Adding in stages gives you damp coir for trays rather than a sodden mass you have to drain.
How many litres does a coco briquette make?
Expect about 8 to 9 litres of loosely filled medium from a 650 g briquette. Labels quote anything from 6.5 to 11 litres because brick weight varies between about 550 and 700 g and because people measure loose or settled volume differently. Hydrate one and measure it into a container you know, then plan on that.
How long should a coco briquette soak?
With warm water a briquette slumps in 5 to 15 minutes and is fully workable within half an hour. Cold water can take an hour or more and may leave a dry core. If you find hard lumps when fluffing, add a little more water and wait another ten minutes rather than forcing them apart.
Can I sow seeds directly into coco briquette coir?
Yes, if the coir tests below about 0.7 mS/cm in a 1:1.5 or 1:2 dilution. Washed coir usually does. If it tests higher, give it one rinse in fresh water, drain to damp and then fill your trays. Many growers add a share of perlite or vermiculite for small plugs but it isn't essential.
Do I need to buffer briquette coir before propagation?
Not for germination. Unbuffered washed coir carries seedlings through to true leaves without a problem. The calcium and magnesium exchange that buffering addresses matters more once you're feeding regularly, and you handle it by including calcium and magnesium in the feed from the first application.
Should I sieve coco peat for plug trays?
For 50- or 72-cell trays, no. For 288 plugs and smaller cells, yes, because long fibres bridge the cell and leave air gaps under the seed. A 6 mm garden sieve takes out the fibre in a few minutes, or you can order a fine or screened grade so the step isn't needed.
How long does hydrated coir from a briquette keep?
Two to three weeks in a lidded tub out of the sun is comfortable. It must stay damp, since dried coir resists rewetting, and it must not go sour or grow surface mould. A dry, unopened briquette in its wrapper keeps for years as long as it stays dry.
Is a 650 g briquette the same coir as a 5 kg block?
From the same factory, yes. It's the same washed pith pressed into a smaller brick. The difference is handling: a briquette hydrates in a bucket in minutes, a block needs a large tub and 20 to 30 litres of water. Blocks cost less per litre, briquettes cost less in labour for small batches.