The short answer: this is a plain-English glossary of the words you'll see on coco coir spec sheets, quotes and growing guides. Coco peat, coir pith and coco coir mostly mean the same thing (the spongy material from the coconut husk), while terms like EC, AFP, CEC and dry-back describe how that material holds water, air and nutrients. Each entry is one to three sentences. Where we have a longer article on a term, it's linked.
A
Ageing. Storing sieved coir pith in heaps for months before washing and pressing. Microbes break down easy carbon, and phenolic compounds leach out, which makes the pith more stable and less likely to tie up nitrogen. See aged vs fresh coco peat.
Air-filled porosity (AFP). The share of a substrate's volume that holds air after it has been saturated and allowed to drain. It tells you how much oxygen the roots get. Coir's AFP depends mostly on particle size and how much chip or fibre is in the mix. See water holding and air porosity in coco coir.
B
Bale. A large pressed pack of loose coir pith or fibre, used mostly by potting-mix makers who break it open and blend it.
Block. A pressed brick of coco peat, most often 5 kg, that expands when water is added. Blocks are the standard bulk format for mixing.
Bristle fibre. The longest, stiffest grade of coconut fibre, combed out of the husk and used for brushes, brooms and some horticultural products.
Briquette. A small pressed brick of coco peat, commonly 650 g. It's the same material as a block in a size that's easier to handle.
Brown fibre. Fibre extracted from mature, usually dry or semi-dry husks, mostly by machine. It's tough and resilient and goes into brushes, rubberised coir and mattresses.
Buffering. Soaking coir pith in a calcium solution, usually calcium nitrate and sometimes magnesium, so that calcium replaces sodium and potassium held on the exchange sites. It's an optional step after washing. See buffered vs unbuffered coco peat.
Bulk density. The weight of a given volume of substrate, usually dry weight per litre or cubic metre. Coir is very light when loose and dry, roughly 70 kg/m³, and far denser when pressed.
C
Calcium nitrate. A fertiliser salt used both in nutrient solutions and, by some producers, to buffer coir. Unbuffered coir hasn't had this treatment.
Cation exchange capacity (CEC). A measure of how many positively charged nutrient ions (calcium, magnesium, potassium, sodium, ammonium) a material can hold on its surfaces. Coir's CEC is moderate and variable, and it's the reason buffering exists. See coco coir cation exchange capacity.
C:N ratio. The ratio of carbon to nitrogen in an organic material. Fresh coir pith has a wide ratio, which lets microbes compete with roots for nitrogen. Ageing narrows it.
Coco coir. A loose umbrella term for growing media made from coconut husk. In shops it often means pith, sometimes with chips or fibre mixed in.
Coco peat. The common trade name for processed coir pith used as a growing medium. It isn't peat. Nothing about it is formed in a bog.
Coir. Strictly, the fibre from the coconut husk. In horticulture the word is used for all husk-based products, fibre and pith alike.
Coir pith. The spongy, corky material between the fibres of the husk, left behind when the fibre is extracted. Processed, it becomes coco peat.
Combing. A fibre-extraction method in which husks are held against fast drums set with steel spikes that comb out the binding material and the pith. It produces bristle fibre. Also called defibering.
Compression. Pressing dried coir into blocks, briquettes or slabs to save freight. Pressed coir sits at around 400 kg/m³ at about 20% moisture.
D
Decorticator. A machine that beats soaked or dry husks with bars on a rotor to separate fibre from pith. It gives mixed-length fibre.
Defibering. The general term for separating fibre from the husk by machine. In some standards it means combing specifically, as opposed to decorticating.
Drain (runoff). The water and nutrient solution that runs out of a slab or pot after irrigation. Growers measure its volume, EC and pH to steer feeding.
Dry-back. The fall in substrate water content between one irrigation and the next, usually tracked overnight or between the last and first irrigation of the day. Larger dry-backs push plants toward generative growth, smaller ones toward vegetative growth.
E
EC (electrical conductivity). A measure of how much dissolved salt is in a solution, read in mS/cm or dS/m. For coir it tells you how much soluble salt (mainly sodium, potassium and chloride) is in the material. Unwashed coir can read 6 mS/cm or more in a 1:1.5 extract, washed coir normally under 1.
Expansion. The increase in volume when compressed coir takes up water. A block expands to about four to six times its pressed volume, depending on how much fibre and chip it contains.
Extraction method. The lab procedure used to measure EC and pH, such as a 1:1.5 volume extract, a 1:5 extract or a saturated media extract. Different methods give different numbers for the same coir, so always compare like with like.
F
Fibre content. The share of fibre in a coir product. More fibre generally means more air and a longer-lasting substrate, and less water held.
Fines. The smallest particles in a substrate. Too many fines hold water tightly and cut air, especially at the bottom of a slab.
Flushing. Running plain water or a weak solution through the substrate to wash out excess salts. Growers do it at the start of a crop and when drain EC climbs too high.
G
Grade. A named specification for a coir product, usually defined by particle size, EC, and the share of pith, chip and fibre.
Grow bag. A plastic sleeve holding a compressed coir slab, which the grower expands by irrigating in place. It's used for tomatoes, cucumbers, peppers and strawberries.
H
Husk. The thick fibrous outer layer of the coconut (the mesocarp). It's the raw material for all coir products and makes up about 35% of the whole coconut's weight.
Husk chips. Coconut husk cut into chunks, washed, and sold loose or pressed into blocks. They add air and long life to a mix. Some suppliers call coarse cut husk "crush".
Hydration. Adding water to compressed coir so it expands and becomes usable. Break blocks up as they soften so the water reaches the middle.
Hydrophobic. Water-repellent. Some media resist rewetting once they dry out completely. Coir is far less prone to this than many other potting-mix components.
L
Leaching. Washing soluble salts or nutrients down and out of a substrate with water. Washing coir at the factory is a form of leaching.
Lignin. A tough natural polymer in plant cell walls. Coir is high in lignin, which is why it breaks down slowly and keeps its structure through a long crop.
M
Mattress fibre. The shorter, less stiff grade of brown coconut fibre, used for mattresses and upholstery.
Mesocarp. The botanical name for the husk layer of the coconut, between the outer skin and the hard shell.
Moisture content. The share of a product's weight that is water. It explains why two blocks of the same size can weigh differently, and it's part of every block specification.
N
Nitrogen drawdown. Microbes in fresh or poorly aged organic material taking nitrogen from the feed, leaving plants short. It shows as pale growth early in a crop. See nitrogen drawdown in coco coir.
O
Open-top bag. A bag of compressed coir with an open top, expanded with water and planted directly. It's common for strawberries, cane fruit and nursery stock.
P
Particle size distribution. The spread of particle sizes in a substrate, measured by sieving. It decides the balance of air and water more than any other property.
Peat-free. A growing medium with no sphagnum peat in it. Coir is one of the main peat-free ingredients.
pH. A measure of acidity or alkalinity. Coir usually sits between about 6 and 7, so it needs no liming.
Phenolics. Natural compounds in the coconut husk, including tannins, that can harm roots and germination when fresh. Ageing and washing reduce them.
Phytosanitary certificate. An official plant-health certificate issued by the exporting country's plant protection service, required by many importing countries for coir.
Plant holes. Holes cut in the top film of a grow bag where the transplants go. Their number and spacing set the plant density along the bag.
R
Rehydration. Wetting coir that has dried out, either after pressing or in storage. Coir takes water back up readily, which is one of its strengths.
Retting. Soaking husks in water, traditionally in brackish backwaters for six to ten months, so microbes break down the material binding the fibre. Retted husks give fine white fibre.
S
Saturated media extract (SME). A lab method in which the substrate is wetted to saturation and the liquid drawn off for testing EC, pH and nutrients. It reads differently from volume-ratio extracts.
Sieve grade. The screen size used to grade coir pith, such as quarter-inch (about 6 mm). Quarter-inch pith is the most common horticultural grade and has an air content of about 20%.
Slab. A flat, compressed block of coir sized for one row of plants, usually sold inside a grow bag. Once irrigated it swells to full height.
Sodium. One of the main salts in unwashed coir, along with potassium and chloride. High sodium damages sensitive crops, so it's one of the first things checked on a spec sheet.
T
Tannins. Brown, water-soluble phenolic compounds from the husk. They colour the first drain water from fresh coir and fall with ageing and washing.
U
Unbuffered. Coir that has been washed but not treated with a calcium solution. Growers using it add a little extra calcium and magnesium in the first feeds.
Unwashed. Coir that hasn't been rinsed after extraction. It carries high salt levels and isn't suitable for most growing without treatment.
W
Washing. Flushing coir pith with fresh water to remove soluble salts and lower EC. Results depend on the quality of the water used and the number of passes. Read how it fits into the whole process in how coco peat is made.
Water-holding capacity. How much water a substrate holds after drainage, by volume or weight. Coir holds a lot, and the amount falls as particle size and fibre content rise.
White fibre. Fine, light-coloured fibre from husks retted in water, used mainly for spinning yarn.
If a term on your spec sheet isn't here, or you'd like help reading a supplier's data, ask us.
FAQ
Is coco peat the same as coco coir?
Mostly, yes. Coco peat and coir pith refer to the spongy material from the husk, while coco coir is a broader term that can include pith, chips and fibre. Check the product description to see which you're getting.
What does EC mean on a coco peat spec sheet?
EC is electrical conductivity, a measure of the soluble salts in the coir. Lower is better for most uses. Always check which extraction method was used, because the same coir reads differently in a 1:1.5 extract, a 1:5 extract or a saturated media extract.
What is AFP in growing media?
AFP stands for air-filled porosity, the share of the substrate's volume that holds air after it drains. It tells you how much oxygen reaches the roots. Coarser coir and mixes with chips have a higher AFP.
What does buffered mean for coco coir?
Buffered coir has been treated with a calcium solution, usually calcium nitrate, to swap sodium and potassium on the exchange sites for calcium. Unbuffered coir has only been washed. Both can be grown in, with slightly different feeding at the start.
What is dry-back in coco coir?
Dry-back is how much the substrate's water content falls between one irrigation and the next, often measured overnight. Growers use it to steer plants toward leaf growth or fruiting. Larger dry-backs push plants toward generative growth.
What is the difference between retting and decorticating?
Retting softens husks by soaking them in water for months so microbes loosen the fibre. Decorticating separates fibre and pith mechanically by beating the husk in a machine, with or without a short soak first. Many mills today rely on machines rather than long retting.