The short answer: coco coir holds roughly twice the water of wood fibre, rewets easily, keeps its structure for several years and doesn't draw nitrogen out of the feed. Wood fibre holds more air, costs less per litre when the plant is near your farm, and is the one peat replacement Europe can make locally at scale. Its weak points are a thin water buffer and nitrogen immobilisation, which is why almost nobody uses it alone. Coir is the stand-alone base. Wood fibre is the opener you add to it. Most blenders now use both.
Key facts
- Water holding by volume: coir about 40%, wood fibre 20 to 25%. Air-filled porosity: coir 13 to 28%, wood fibre 30 to 35%.
- Wood fibre ties up 100 to 150 mg of nitrogen per litre as microbes colonise it. Coir pith releases potassium instead, 170 to 600 ppm in the raw material.
- Mixes with up to 30% wood fibre grow normal crops without extra feed. At 60% wood fibre, petunias miss marketable quality even with more nitrogen.
How each one is made
Coco coir is the pith and short fibre left when coconut husks are processed for long fibre. It's a by-product, and around 90% of it comes from the Philippines, Indonesia, India and Sri Lanka. For horticulture it's aged, washed to lower salts, sometimes buffered with calcium nitrate to displace sodium and potassium, then dried and compressed. Our coco peat from Kanyakumari, Tamil Nadu, India is washed with water to reduce EC. No calcium nitrate or other chemicals are used and it isn't buffered. The trade-offs of buying it that way are in buffered vs unbuffered coco peat.
Wood fibre is made from fresh, de-barked spruce or pine chips forced through a small aperture or refiner under pressure and heat. The friction shreds the wood into thin strands, sterilises it and stabilises it. Producers hygienise the raw material at over 90 °C. Bark share matters: about 5% is fine, more than that holds back growth because of the tannins and terpenes in fresh bark. Early fibres were impregnated with nitrogen during defibration to counter drawdown. That gave erratic salt levels and poor storage life, so the big producers now leave the fibre plain and add a nitrogen reserve at the blending stage.
In short: coir is a wet, salty by-product cleaned up for use. Wood fibre is a clean, dry, low-salt material made on purpose, with a nitrogen problem built in.
Physical properties side by side
| Property | Coco coir (pith) | Wood fibre |
|---|---|---|
| Total pore space | 86 to 94% | Over 90% |
| Air-filled porosity | 13 to 28% (9 to 14% in fine pith at saturation) | 30 to 35% |
| Water holding by volume | About 40%, easily available water around 35% | 20 to 25% |
| Dry bulk density | About 80 kg/m³ | 80 to 150 kg/m³ by grade and compaction |
| Rewetting after drying | Easy | Varies, some products clump when wetted alone |
| Compression for transport | 5 to 6 : 1 | About 1.4 : 1 |
| Structural life | 3 to 4 years in berry crops, 4 to 5 in cool climates | Not yet established, compresses under load |
Coir's advantage is the water buffer. Fine pith gives up about 35% of its volume as easily available water, so a missed irrigation cycle costs you little. Wood fibre drains fast and holds little easily available water, which means shorter, more frequent pulses and a dry top layer that can slow establishment. Fines help: a fibre fraction with everything under 1 mm reaches about 95% maximum water capacity, one with no fines about 70%.
Where wood fibre wins is air. It opens pore space, cuts bulk density and dries the surface faster, which helps against algae and fungus gnats. In peat blends measured in the same lab, 30% coir pushed water-filled pore space up to about 59% and air down to about 30%, while 30% wood fibre left both almost where 100% peat sat (52% water, 34% air). They pull a blend in opposite directions, which is why they pair well. For measuring these numbers in your own mix, see coco coir water holding and air porosity.
Chemistry: salts, pH, CEC and nitrogen
| Property | Coco coir | Wood fibre |
|---|---|---|
| pH as supplied | 5.5 to 6.8 | 5.0 to 7.5, usually near neutral |
| EC | Variable, 0.4 to 6.0 dS/m across raw coir from six countries, low after washing | Low, no washing needed |
| Cation exchange capacity | High, anything from 30 to 100 meq/100 g is quoted | Lower than coir |
| Native nutrients | Potassium 170 to 600 ppm, phosphorus 6 to 60 ppm, sodium and chloride if unwashed | Almost none |
| Carbon to nitrogen ratio | Moderate | 100 to 270 : 1 |
| Nitrogen behaviour | Little drawdown in aged pith | Immobilises 100 to 150 mg N/L, strongest in the first weeks |
Coir's issue is cations. The pith carries potassium and, if it's grown near the coast or processed in brackish water, sodium and chloride. Its high cation exchange capacity holds those ions and swaps them for the calcium and magnesium in your feed, which is why unbuffered coir wants a calcium-rich start. The upside of that CEC is a pH that moves slowly and a root zone that forgives a feed mistake.
Wood fibre's issue is nitrogen. Fresh wood sits above 100:1 carbon to nitrogen, and microbes colonising it take mineral nitrogen from your feed to build protein. In an incubation test wood fibre locked up 115 mg of nitrogen per litre within four days, between 27% and 92% of what was applied depending on the dose. Lettuce in a 40% wood fibre mix lost 39 to 57% of its biomass against peat at the same nitrogen rates. Commercial fibres are steadier, with producers quoting a constant 100 to 150 mg/L that they cover with a nitrogen store in the blend. Cucumber in straight wood fibre matched peat for height and leaf number only when fed extra ammonium nitrate. The practical answer is a higher starting nitrogen charge or a controlled-release source, plus weekly pour-through checks for the first month.
Stability over long crops
Coir contains more lignin and less cellulose than peat, so it resists breakdown and shrinks less. Berry growers run the same coir for three or four seasons. In a Spanish tomato trial that reused the same bags for four successive crops, coir, wood fibre and perlite yielded alike for three cycles, and only in the fourth did coir fall behind.
Wood fibre's long-term stability is the open question. It's rarely used alone because it retains too little available water and tends to compress. Producers are working on lignin-enriched fibre that breaks down more slowly, but there's no multi-year berry data yet. If you keep a substrate for more than one season, coir is the safer base.
Supply, price and carbon in plain terms
Coir is cheap to make and expensive to move. It's compressed 5 to 6 : 1 and shipped by container, so its price follows freight rates, the monsoon, husk availability and export conditions. Lead times to Australia stretched from nine or ten weeks to six or seven months during the 2021 to 2022 shipping squeeze, and growers there put up to half of their delivered cost down to freight. Husk prices in India rose again in 2026 after a dry season.
Wood fibre is expensive to make and cheap to move short distances. The machinery is a large capital outlay, after which running costs sit close to peat. It barely compresses, so freight per usable cubic metre climbs fast with distance. It makes sense when the plant is within a couple of hundred kilometres of the farm, which in Germany, the Netherlands, Ireland or Scandinavia it often is. Its price tracks timber, so it tracks the building trade and the pellet market. Irish growers name wood fibre their most used peat alternative and, in the same breath, high cost and limited availability as the main problems with switching.
On carbon the picture is simple. Coir carries shipping emissions: one estimate for coir moved about 10,500 km by sea came to roughly 2.5 tonnes of CO₂ equivalent per hectare of berry production, small against the crop's other inputs but not nothing. Wood fibre carries the energy of defibration and local trucking. Neither is peat, which is the point of both.
Where each one wins
Wood fibre wins on
- Air-filled porosity and drainage in dense mixes
- Local supply and short freight within Europe and North America
- Cost per litre at the gate when the plant is nearby
- No salts, so no washing, no sodium, no buffering
Coco coir wins on
- Water buffer and easily available water
- Rewetting after a dry-back
- Structural life across multi-year crops
- No nitrogen drawdown in aged, washed pith
- Transport density and use at 100% as a stand-alone slab or bag substrate
Typical blend ratios
Nobody has to choose one. These ratios show up in commercial recipes and trials:
| Blend | Where it's used | What to watch |
|---|---|---|
| 75% coir : 25% wood fibre | Raspberry and blackberry pots, container nursery stock | Top layer dries sooner, establishment a little slower. Yields matched 100% coir |
| 66% coir : 17% bark : 17% wood fibre | Hardy nursery stock, peat-free | Marketable plants equal to the peat standard |
| 50% coir : 50% wood fibre | Peat-free potting and nursery mixes | Extra nitrogen reserve, shorter irrigation cycles |
| 70% peat : 30% wood fibre | Reduced-peat bedding and pot plants | No measurable nitrogen tie-up at 100 to 200 ppm N. Above 30%, raise the feed |
A good rule: let coir set the water and wood fibre set the air. If the mix drains too slowly, add fibre in 10% steps. If it dries too fast or shrinks, add pith or husk chips. For the blending-line side, including coir's weight and wood fibre's nitrogen in the same recipe, see coco peat for potting mix producers.
Trial results, stated as ranges
- Petunia in 70:30 peat:wood fibre at 200 ppm N: marketable, dark green, 45 or more flowers per plant. In one of two experiments plants were slightly shorter and narrower than 100% peat. Nitrogen drawdown index sat at 1.0, meaning no net tie-up.
- Petunia at 60% wood fibre: shoot mass and flowers fell with fibre share and plants missed marketable quality. Extra nitrogen fixed it in only a few cases, so water was limiting too.
- Lettuce at 40% wood fibre: biomass down 39 to 57%, leaf nitrogen down 7 to 40%, chlorophyll down 14 to 36% versus peat.
- Tomato over four cycles in reused bags: no difference between coir, wood fibre and perlite for three crops. Melon over one cycle: no yield difference.
- Raspberry in 75:25 coir:wood fibre: yields similar to 100% coir, slightly better growth after establishment put down to the extra air.
- Berry gross margin, coir versus locally made wood fibre: 64.4% against 64.5%, and only because fibre was assumed made within 100 km.
Up to about 30% wood fibre is a free upgrade in air. Between 30 and 50% you manage nitrogen and water harder and still do well. Above 50%, coir or peat has to carry the water.
For bark, perlite, rice hulls and the rest, read coco coir alternatives compared. If you're blending both materials, we supply washed, unbuffered coco peat as blocks and as custom blends with husk chips and fibre. Contact us with your target air and water numbers and we'll match a grade.
FAQ
Is wood fibre better than coco coir?
Neither wins across the board. Wood fibre has more air, lower salts and shorter freight in Europe. Coir holds about twice the water, rewets easily, lasts several seasons and doesn't tie up nitrogen. Most blenders use coir as the base and wood fibre to open it up.
Can wood fibre replace coco coir completely?
Rarely. On its own it holds too little available water, tends to compress and immobilises nitrogen as microbes colonise it. Some products clump when wetted alone. It works at 25 to 50% of a coir or peat mix, and at 30% or less without any change to feeding.
Why does wood fibre cause nitrogen deficiency?
Fresh wood has a carbon to nitrogen ratio above 100 to 1. Microbes breaking it down take mineral nitrogen from the feed, locking up about 100 to 150 mg per litre, mostly in the first weeks. Commercial blends add a nitrogen store to cover it. Check pour-through nitrate weekly for the first month.
Does coco coir tie up nitrogen too?
Aged, washed pith shows little drawdown. In peat blends with 30% coir the nitrogen drawdown index sat at about 1.0, the same as peat. Coir's chemistry issue runs the other way: it carries potassium and sometimes sodium that exchange with the calcium and magnesium in your feed.
Which holds more water, coir or wood fibre?
Coir. Fine pith holds around 40% of its volume as water with about 35% easily available. Wood fibre holds 20 to 25%, drains fast and buffers poorly, so it needs shorter, more frequent irrigation pulses. Adding fines to the fibre raises its water holding.
Which is cheaper, coco coir or wood fibre?
It depends on distance. Wood fibre is usually cheaper at the factory gate but compresses only about 1.4 to 1, so freight climbs fast beyond a couple of hundred kilometres. Coir compresses 5 to 6 to 1 and ships worldwide, with its price following container rates and husk supply. A berry gross-margin model showed almost no difference once fibre was made locally.
What is a good coir and wood fibre blend ratio?
Start at 75% coir to 25% wood fibre. Berry trials at that ratio matched 100% coir. Nursery mixes run 50:50 or 66% coir with 17% bark and 17% wood fibre. Go up in 10% fibre steps if you need more drainage, and budget extra nitrogen and more frequent irrigation once fibre passes 30%.
Which lasts longer in a multi-year crop?
Coir. Its high lignin content resists breakdown, and berry growers run the same coir for three to four seasons. In a tomato trial reusing bags for four crops, coir matched wood fibre and perlite for three cycles. Wood fibre's multi-year stability is still being tested and it tends to compress under load.