The short answer: coir is now the default substrate for raspberries, blackberries and most other protected soft fruit, and it works for cane fruit if you pick a coarser grade than you would for strawberries, give the roots 7 to 12 litres per pot, and run the feed hotter and the pots wetter than a table-top strawberry bag. The crop sits in the same pot for two to three seasons, so the structure has to hold up. A fine, dusty pith that is fine for a one-season strawberry crop will slump, drain badly and cost you yield in year two.
This guide is for growers moving cane fruit out of soil or peat. Strawberries and blueberries have their own guides: growing strawberries in coco coir and growing blueberries in coco coir.
Why soft fruit moved off the soil
Root disease. Raspberry root rot (Phytophthora rubi) is soil-borne and persistent. Once it is in a field it stays, and the few chemical controls are hard to fit around planting dates. A pot of clean substrate on a leg or a gravel floor cuts the plant off from infected ground. That alone is why many cane-fruit growers moved.
Picking height. Pots on a raised floor or troughs on legs lift the fruiting zone to a comfortable height. Pickers move faster, drop less fruit and come back next season. Labour is the biggest cost line in berries, so anything that lifts pick rate pays for itself.
Season extension. Long-cane raspberries are grown to length in a nursery, held in cold store at about -2 to -3 °C, and planted into pots on a date you choose. Stagger plantings and you spread the season instead of taking one summer peak.
Consistency. A pot of washed coir is the same at both ends of the tunnel. Field soil isn't. Uniform rooting volume means uniform irrigation, uniform vigour and a predictable picking window.
Coir won out over peat because it holds its structure longer under heavy irrigation, re-wets more readily, and sits outside the peat phase-outs. In a long-cane raspberry trial that tested aged pine bark against coir, coir was simply the industry standard the bark had to match. See the berry applications page for formats.
Which crops suit coir
| Crop | System | How it runs in coir |
|---|---|---|
| Raspberry, long cane | Chilled canes planted into 5–10 L pots, 6 canes per linear metre | The main substrate cane crop. One or two fruiting seasons per pot |
| Raspberry, primocane | Pots or troughs, 10–20 L | Autumn crop or double-cropped, 2–3 seasons in the same pot |
| Blackberry, long cane | Pots with 6–12 canes each, 12 canes per linear metre | Vigorous roots, wants the larger volumes and coarsest mixes |
| Strawberry | Table-top bags and troughs | Own guide |
| Blueberry | Large pots, acidic feed | Own guide |
| Cherry on dwarfing rootstock | Large containers under cover | Small scale so far on rootstocks such as Gisela 5. Little published trial data |
Cherries deserve a note. Pot-grown cherry under tunnels is real, but it's a tree in a large container with a life of many years. Treat it as a container-nursery problem rather than a soft-fruit one: chip-heavy blend, big pot, refresh the top layer each spring rather than the whole volume.
Pot and trough volumes for cane fruit
Published volumes scatter because the system dictates the pot.
| Stage or system | Volume you'll see quoted |
|---|---|
| Nursery long cane, growing the cane | 1.8–4.7 L |
| Single-cane raspberry, one fruiting season | 5–7.5 L |
| Standard long-cane fruiting pot | 7 L, often called the ideal size. 10 L runs similarly at higher cost |
| Two-year raspberry crop | 10–12 L |
| Primocane raspberry, organic systems | 20 L |
| Troughs | 2 m lengths holding several plants |
Two trial results matter. Nursery canes grown on in 4.7 L pots collapsed about 25 % less after planting than canes from 1.8 L pots, so the small nursery pot is a false economy if you grow your own canes. And in a Northern Ireland demonstration that ran coir in 12 L containers alongside 2 m coir troughs, the troughs gave the strongest raspberry crop over time. Troughs give roots a shared, cooler volume, irrigate more evenly and leave less plastic to dispose of. The trade is that a disease problem travels the whole trough.
Pots on legs matter more for cane fruit than for strawberries. Raspberry roots hate standing water, and a leg that lifts the base clear of the floor is cheap insurance against Phytophthora in the drain puddle.
Coir grades for cane fruit: go coarser
Strawberry bags are usually fine to medium pith with some fibre. Cane fruit wants more chips.
The reason is time. A one-season strawberry crop doesn't live long enough for coir to slump. A raspberry or blackberry pot is under daily irrigation for two to three years, and fines settle. When a reuse project tracked second-year coir, settled fines and dead roots from year one had cut porosity and blocked drainage enough to waterlog the root zone and drop yield by over a quarter. The same project found that coarser, chip-rich coir held its structure better than fine pith in a second season.
A standard coir mix can carry up to 20 % dust by volume. Some suppliers screen out everything below 2 mm for berry crops.
| Fraction | Strawberry bag | Cane fruit pot |
|---|---|---|
| Fine pith | Majority | Reduced, enough to hold water between cycles |
| Fibre | Some | Some, for structure |
| Husk chips | Little or none | A substantial share by volume, more for blackberries and three-season crops |
Suppliers don't publish one standard chip ratio, so ask for the chip share by volume and compare like with like. Our husk chips and custom blends cover these mixes, and the husk chips guide explains how chip size changes air and water. Perlite does the same job: a common North American long-cane mix is washed coir with 30 % perlite. Chips are lighter to ship, break down cleanly and cost less, but hold a little more water per litre.
Our coco peat is washed with water to lower EC and is not buffered, so run extra calcium and magnesium for the first weeks. Buffered vs unbuffered coco peat covers the choice.
Irrigation and EC: how cane fruit differs from strawberries
Higher EC. Strawberries in coir run at about 1.0 to 1.6 mS/cm feed. For raspberries in coir you'll see fruiting-stage figures from 1.5 to 2.2 mS/cm in European and New Zealand work, while some North American long-cane growers run 3.0 in fruiting and 3.5 in vegetative growth. Start near the low end with unbuffered coir and let drain EC and leaf colour tell you where to settle. Hold pH around 5.6 to 5.8.
More magnesium, less calcium. Raspberries take up more magnesium relative to calcium than strawberries do. A strawberry feed will run a raspberry crop short of magnesium by mid-season. Watch for interveinal yellowing on older leaves.
More water, more often. A fruiting cane under plastic in July is a big transpiring plant. Field raspberries pull up to 6 mm a day at peak, and a 7 L pot has little buffer. Long-cane growers run 12 to 15 cycles a day of 3 to 5 minutes each in high summer, against a handful for a strawberry bag. Aim for 10 to 20 % drain over the day and flush when drain EC climbs. A 13 to 14 litre flush per 18 L bag is the kind of volume used to reset pore EC in berry coir.
Dry coir with a high chip fraction can be hydrophobic. Wet it through in a tub or on a wetting line before potting. Rewetting dry coco coir explains why.
Winter management of coir pots
A raspberry root system in a pot sees the air temperature, not the soil temperature.
- Roots are less hardy than canes. In freezing trials on potted raspberries, 'Glen Ample' roots showed injury at -10 to -12 °C while canes were fine. Hardier cultivars tolerated -18 °C. A pot at -10 °C is a normal night in a cold tunnel in northern Europe.
- Protect the pot, not the cane. Push pots tight together, bank the outside rows with fleece or straw, or drop the tunnel sides. In very cold regions growers sink pots to the rim or move them into cold store at -2 °C.
- Don't let it dry out. Dormant coir in an unheated tunnel still loses water. Coir that dries hard over winter re-wets slowly in spring, shrinks from the pot wall and channels. A hand watering or two a month in a dry winter is enough. Don't feed.
- Lines and drippers. Blow lines down before hard frost and lift drippers off the pot surface.
Substrate life for a two-to-three-year crop
A long-cane floricane raspberry is usually one fruiting season, sometimes two. Primocane raspberries and blackberries commonly go two or three. Fines settle, chips break down slowly, root mass fills the pot, the level drops and drainage slows. Salt builds in the lower third if drain has been tight.
- Start coarser than you think you need. This buys more than any later fix.
- Top up each spring with fresh chip-heavy coir to restore the level and open the surface.
- Flush at the end of each season and again before growth starts, so the crop restarts at a known drain EC.
- Keep drain at 10 to 20 % through the season rather than letting the pot go tight and flushing hard.
- Replace the whole volume when the plant is replaced. See reusing coco coir before putting used coir under another berry crop, since second-use yields fall unless it's reconditioned.
Labour and setup: what changes
Substrate raises your fixed cost and lowers your variable one. Up front you buy pots or troughs, floor cover or legs, drip with per-row control, and a fertigation unit with A and B tanks plus acid. Chilled long canes cost more per plant than bare-root stock and some vendors want orders a year ahead.
Ongoing, you pay for substrate and plants on a one-to-three-year cycle, fertiliser and water. Weed control disappears. Picking labour per kilo falls because of the height and the denser, more uniform crop. Breakeven for long-cane raspberries at 6 canes per metre is quoted around 800 g per cane, with good growers targeting 1.2 kg.
Coir arrives as compressed blocks you hydrate on site or as bags filled in the factory. For a few thousand pots, hydrating blocks on a mixing floor is cheap and gives you control over the chip ratio. For tens of thousands, pre-filled grow bags or supplier-filled pots save a lot of handling. The bulk buying guide runs through formats.
Common mistakes when switching
- Strawberry coir for cane fruit. It slumps in year two. Specify chips.
- Pots too small. A 1.8 L nursery pot is not a fruiting pot. A fruiting long cane wants 7 L minimum.
- Running the strawberry recipe. Too little EC, too little magnesium, too few cycles.
- Dry potting. Chip-heavy coir needs wetting through before the plant goes in.
- Pots on the ground. Roots in the drain puddle are roots in Phytophthora.
- Forgetting winter. Frozen roots and bone-dry pots in March are both avoidable.
- Not measuring drain. Pore EC in a 7 L pot moves fast. Measure drain EC weekly at minimum. Coco coir pH and EC management covers meters, sampling and corrections.
If you're specifying coir for a cane-fruit planting, tell us the pot volume, crop life and whether you want chips blended in, and we'll put together a sample and a quote. Get in touch.
FAQ
What pot size do I need for raspberries in coir?
For a fruiting long cane, 7 litres is the size most growers settle on, with 10 litres performing similarly at higher cost. Single-cane plants grown for one season manage in 5 to 7.5 litres. If the crop is staying two years, go to 10 to 12 litres. Nursery pots of 1.8 to 4.7 litres are for growing the cane, not fruiting it.
Can I use the same coir for raspberries as for strawberries?
You can, but not for a crop that runs more than one season. Strawberry coir is mostly fine pith and will settle and drain poorly in year two. For cane fruit, pick a blend with a substantial share of husk chips so the structure holds up under two or three years of daily irrigation.
What EC should I run for raspberries in coir?
Fruiting-stage feed EC of 1.5 to 2.2 mS/cm is the range most European and New Zealand work lands in, with some North American long-cane growers running 3.0 or higher. Start lower with unbuffered coir and move up as drain EC and leaf colour allow. Keep pH near 5.6 to 5.8.
How often should I irrigate raspberries in 7 litre pots?
In high summer under plastic, long-cane growers run 12 to 15 short cycles a day of 3 to 5 minutes each. Aim for 10 to 20 percent of applied water as drain across the day and flush when drain EC rises. In spring and autumn you'll drop to a few cycles a day.
Will raspberry roots in coir pots survive winter outside?
Depends on the cultivar and how cold it gets. Potted roots of some cultivars show injury at minus 10 to minus 12 degrees Celsius while hardier ones tolerate minus 18. Roots are less hardy than canes. Push pots tight together, insulate the outer rows or move pots into cold store, and keep the coir slightly moist all winter.
How long does coir last for a blackberry or raspberry crop?
Two to three seasons in the same pot is normal if you start with a chip-rich blend, top up each spring and flush at the end of each season. Fine coir can lose drainage and yield in its second year. Replace the full volume when the plant is replaced.
Is coir better than peat or pine bark for cane fruit?
Coir holds structure longer than peat under heavy irrigation and re-wets more easily, which is why it became the standard. In a one-year trial, aged pine bark gave the same raspberry yield as coir, so bark is a workable local alternative where it's cheap. Peat is being phased out in several markets.
Can I grow cherries in pots in coir?
Yes, on dwarfing rootstocks such as Gisela 5, in large containers under cover. There's little published trial data on commercial coir-grown cherries, so treat it as a container-nursery crop: coarse, chip-heavy mix, big pot, top-dress each spring rather than repotting.