The short answer: spent coco coir is non-hazardous plant-tissue waste, and the best thing to do with it is almost never to throw it away. Strip the plastic, keep diseased crops separate, and it will go into a second crop, into field soil, into a compost windrow or to a landscaper. Landfill is the last option and the dearest. The work is in the sleeve, the root mass and the paperwork, not in the coir.
This article is for greenhouses and nurseries handling the material by the tonne. If you're still deciding whether to run another crop in it, read can you reuse coco coir first.
How much a hectare produces
Multiply slabs per hectare by litres per slab. The figures below are the ones used in published waste estimates.
| System | Units per ha | Litres each | Volume per ha | Dry weight at 80 kg/m³ |
|---|---|---|---|---|
| 100 x 15 x 10 cm slabs (tomato, pepper, cucumber, strawberry) | about 7,000 | 15 | about 105 m³ | about 8.4 t |
| 10-litre grow bags (raspberry, blackberry) | about 7,000 | 10 | about 70 m³ | about 5.6 t |
| 10-litre pots (blueberry) | about 2,800 | 10 | about 28 m³ | about 2.2 t |
| Tomato, all substrate waste, as quoted in reviews | up to 150 m³ a year | about 12 t |
Bigger bags (20 to 27 litres are common for long crops) add 20 to 30%. Replacement interval cuts it: tomato and strawberry slabs are changed yearly, cane fruit every one to three years, blueberries every four or so. Water multiplies it. Dry coir weighs 70 to 80 kg/m³, but coir dust holds 7 to 11 times its own weight in water when saturated, so slabs lifted straight off the gutter can weigh five to eight times the dry figure. Switch the irrigation off a week or two before pulling. Dry slabs are cheaper to move, cheaper at the gate and faster to steam.
For scale, Australian berry growers alone produce an estimated 2,500 to 3,500 tonnes of spent coir a year, and the hydroponic vegetable sector there about ten times that.
The options, in order of value
1. A second crop. Tip it out, remove roots, flush, check EC, accept a yield cost. Only when the last crop was clean. Details in the reuse article above.
2. Blending into field soil. If you farm open ground too, this is the cheapest route with real value. Coir raises water holding and air space in heavy soil, and because coir pith is 40% or more lignin it keeps doing so for years. Treat it as a soil conditioner, not a fertiliser, and read the salt notes below.
3. Composting with green waste. Coir alone is poor feedstock. Its carbon to nitrogen ratio is around 100 to 120 to 1 and active composting wants 25 to 30 to 1, so it needs vines, grass, manure or spent mushroom compost mixed in. Done that way, composters say it behaves well and keeps piles open. Composting also solves sanitation. The regimes in UK and EU compost standards are 55°C or more for 14 days in windrows with at least five turnings, 65°C for seven days with two turnings, 60°C for seven days in an aerated static pile, 60°C for two days in-vessel, or 70°C for one hour in-vessel. See coir compost explained for what comes out.
4. Sale or donation to a composter, landscaper or potting-mix maker. Organic recyclers want coir, provided it arrives clean: no film, string, metal clips or rockwool propagation plugs. In Australian consultation, recyclers charged about 40 to 60 dollars a tonne for used coir, roughly half the green-waste fee, which is itself about half the landfill rate. Clean, shredded material in volume was sometimes collected free, because it can go into bagged potting mix (used coir is blended at 5 to 30% by volume) rather than low-value mulch. The working rule was a recycler within about 100 km. Neighbouring growers can pool loads.
5. Mulch. Fine on orchard rows, nursery beds and landscape plantings, with the caveats in the coco coir mulch article. One warning: don't put coir from strawberry or cane fruit under apples, pears, cherries, almonds or roses. Root exudates and the microbes that built up in it can cause replant problems within the same plant family.
6. Anaerobic digestion. Some digesters in Europe take spent coir as part of a mixed feedstock. On its own it's a poor candidate: lignin doesn't break down in a digester and the carbon to nitrogen ratio is far too high, so gas yield is low and most of the coir passes into the digestate. An Australian feasibility review concluded biogas from coir alone was unlikely to pay.
7. Landfill. Legal almost everywhere as non-hazardous waste, and the most expensive option by a distance.
The plastic sleeve, drippers and clips
Every route except landfill starts with separating the coir from everything that isn't coir.
The sleeve is polyethylene film and recyclers reject loads with film in them. At small scale, slit the slab lengthwise as you pull it and shake the coir out. At hectare scale growers build or hire a de-bagging line: a conveyor with a blade and a trommel or shaker that drops coir through a screen and carries the film off the end. Some recyclers run their own plastic-removal machines and take slabs whole, at a higher gate fee. Keep the film dry and baled for an agricultural plastics scheme. Film caked in wet coir goes to general waste.
Drippers, stakes, clips and truss hooks are the contamination recyclers complain about most. Pull them before the slabs leave the gutter. If you're keeping them, soak overnight in a 10% bleach solution and rinse. Rockwool propagation blocks don't compost, so lift them off separately.
Compostable sleeves have been tried, but the film has to be sourced in the country where the coir is compressed and survive a year of irrigation and UV. Growers who want the problem gone have moved to troughs, gutters or pots filled with loose coir. Open-top slabs are the half-way house: no top film to peel off with the roots.
Rules, in general terms
Waste classification. In the EU and UK, spent growing medium sits in chapter 02 of the waste list, agriculture and horticulture. Coir with roots is plant-tissue waste, 02 01 03. The stripped sleeve is 02 01 04, waste plastics other than packaging. Mixed material is 02 01 99. All three are non-hazardous, so no hazardous consignment notes. Duty of care still applies: farm and nursery waste is business waste, it leaves site with a registered carrier and a transfer note, and you keep the records. Burning or burying it on the holding is not an option.
Composting and spreading on your own land. Most jurisdictions allow modest volumes under a registered exemption rather than a permit. In England, the on-farm composting exemption allows up to 80 tonnes on site at any one time when the compost is used where the waste arose, and 60 tonnes if waste comes in from elsewhere. Land spreading is a separate exemption with per-hectare caps, and spreading more than the soil needs counts as disposal. There's no rate for spent coir, but the nearest analogue, used mushroom compost, is capped at 50 tonnes per hectare a year. The English system is being revised from 2027, so check the current version. Other EU countries have equivalents.
Plant health. If the crop had a quarantine disease, the substrate is covered by the same order as the plants. For tomato brown rugose fruit virus, plant-health authorities want growing media and string disposed of with the plants by burning, deep burial or steaming, and they regard ordinary composting as insufficient. Tobamoviruses survive in dried sap on surfaces for at least four weeks and in soil for months. Eight weeks in an enclosed aerated composting system that stayed above 55°C throughout, and above 75°C for 40% of the time, has fully deactivated the virus in stone wool and vines, so the position may soften for approved facilities. Until then, infected coir is a disposal job. For heat treatment of slabs, the long-standing greenhouse guidance is 75°C for 20 minutes for general sanitation and 100°C for 10 minutes after tobacco mosaic or pepper mild mottle virus. For Phytophthora, Pythium, Verticillium, Fusarium, nematodes and thrips pupae, managed hot composting is enough. Moving spent coir across borders to a recycler can bring biosecurity rules into play as well.
Salts and residual fertiliser before soil application
At the end of a tomato or cucumber season, slab runoff EC is commonly around 3 mS/cm and unflushed pockets run higher. Nitrate and potassium leach out as soon as the pile is rained on. Phosphate, sulphate, calcium and magnesium stay, so spent coir carries a fertiliser load skewed to the less soluble elements. Pesticide residues can build up over a long crop too.
- Test it first: EC, pH, carbon to nitrogen ratio and the main nutrients, on a composite sample of the pile you're actually spreading. Spent coir varies with crop, feed recipe, crop length and stockpile time.
- Let rain wash through the pile before spreading on salt-sensitive crops or light soils.
- Count the phosphate if your nutrient plan limits P.
- Expect nitrogen drawdown for a season if you incorporate raw coir rather than compost. Soil microbes will borrow nitrogen from the crop to break down the roots.
- On established trees, keep it as surface mulch off the crown rather than digging it in.
Coir that went in unbuffered, like ours, has been buffered by the first crop's feed, so sodium and potassium shedding is done. Coir treated with calcium nitrate at the factory is the same by the end. What matters now is what you fed, not what the manufacturer did.
Coir versus rockwool at end of life
Growing performance is covered in coco coir vs rockwool. This is the waste side.
| Spent coir | Spent stone wool | |
|---|---|---|
| Material | Lignocellulose, decomposes slowly | Mineral fibre, does not decompose |
| Compost | Yes, with a nitrogen source | Only as a 10 to 25% by weight additive to green-waste compost |
| Soil application | Yes | Limited |
| Recycling route | Composters, potting-mix makers, landscapers, usually arranged by you | Manufacturer take-back where offered: brick clay, new stone wool, engineered soils. Claimed collection rate about 65% worldwide in 2022 |
| Plastic | Sleeve off | Sleeve off, stalks and stems removed |
| Landfill | Last resort, biodegradable | Historically the default. Some countries require return to the manufacturer |
The honest caveat: stone wool take-back is organised and coir's generally isn't. A coir grower usually builds the relationship with a local composter, which is why Australian industry bodies recommended a voluntary stewardship scheme for coir.
Decision table
| Your situation | Best route | Avoid |
|---|---|---|
| Clean crop, you also farm field land | Strip plastic, stockpile, test, incorporate or mulch | Spreading wet and untested |
| Clean crop, composter within 100 km | De-bag on site, shred if you can, negotiate collection | Film, clips or rockwool plugs in the load |
| Clean crop, no composter nearby | On-farm windrow with vines and manure under a registered exemption | Passive piles if the compost will touch fresh produce |
| Berry coir going to an orchard or rose grower | Fine for most crops | Any Rosaceae crop |
| Root disease (Pythium, Phytophthora, Fusarium) | Hot composting to a recognised regime | Direct reuse or mulching |
| Quarantine virus (ToBRFV and similar) | Steam, deep burial or burning as directed | Composting, selling, moving it off site |
| No options at all | Landfill as non-hazardous 02 01 03 | Burning on site |
Plan it in from the start
The waste bill is set when you order the substrate. Slab format, sleeve type and whether you run gutters or bags decide how many hours of de-bagging a hectare costs, so read switching your greenhouse to coir with the end of the crop in mind.
CVM Fiber and Industries makes coco peat blocks, grow bags, open-top slabs, husk chips and custom blends in Kanyakumari, Tamil Nadu, India. Our coco peat is washed with water to reduce EC, with no calcium nitrate or other chemicals, and it isn't buffered. If you want to talk through slab formats that make end-of-crop handling simpler, get in touch.
FAQ
Can spent coco coir go in a normal green-waste skip?
Usually yes, if the sleeve, drippers and clips are off and the crop was healthy. Coir with roots is plant-tissue waste, the same category as hedge trimmings. Check with the operator first, because some composters want to know the carbon to nitrogen ratio and contamination level before taking a large volume.
How much does a hectare of spent coir slabs weigh?
About 8 tonnes dry for 7,000 slabs at 15 litres, and up to about 12 tonnes for 150 cubic metres. Wet, with roots, the same material can weigh five to eight times that. Let slabs drain and dry before you move them.
Do I have to remove the plastic before composting coir?
Yes. Polyethylene film doesn't break down, it contaminates the compost, and most recyclers refuse loads with film in them. Slit the sleeve lengthwise and shake out the coir, or run slabs through a de-bagging line. Bale the film separately for a farm plastics scheme.
Can I spread used coir straight onto fields?
You can if the crop was clean and you test it first for EC, pH and nutrients. Expect phosphate, sulphate and some residual salts, plus a high carbon to nitrogen ratio that ties up nitrogen for a season. Weather the pile through some rain, stay within any spreading limits that apply to you, and keep off frozen or waterlogged ground.
What do I do with coir from a crop that had ToBRFV?
Treat it as infected plant material. Plant-health guidance calls for burning, deep burial or steaming together with the plants and string, and doesn't accept ordinary composting as sufficient. Don't sell it, give it away or move it to a field. Follow your plant-health authority's instructions for the outbreak.
Can coir be composted on its own?
Not well. Its carbon to nitrogen ratio is around 100 to 120 to 1 and composting wants 25 to 30 to 1, so a pure coir pile barely heats. Mix it with vines, grass, manure or spent mushroom compost and manage it to a recognised regime such as 55°C for 14 days with five turnings.
Is rockwool or coir easier to dispose of?
Rockwool is easier to hand over where a take-back scheme exists. Coir has more end uses and decomposes, but you usually find the composter or landscaper yourself. Both need the sleeve off first.