COIR SUBSTRATE BY CROP
Why the same coir-perlite mix does not suit every crop, and how to pick the ratio that matches your irrigation and root zone.
One base, different ratios
Coir and perlite are the two most common substrate components in soilless growing. Coir holds water and nutrients. Perlite adds air space and drainage. The ratio between them determines how wet or how dry the root zone stays between irrigations.
There is no single correct ratio. The right mix depends on the crop, the container size, the irrigation method and the climate.
The industry standard: 70/30 coco-perlite
70 percent coir to 30 percent perlite is the most widely used ratio in hand-watered cannabis production. It is the default recommendation from Grow Weed Easy, Cannabis Training University and Coco Depot, three of the most referenced cultivation resources. A 60/40 mix is also cited where faster drainage is needed.
Our 70/30 coir-perlite mix is not a guess. It is the standard the industry converged on through trial and error over years of commercial production.
Ratios by crop
| Crop | Typical ratio | Why |
|---|---|---|
| Cannabis (hand-watered) | 70/30 coco-perlite | Balances water holding with enough air for frequent feeding |
| Tomatoes (greenhouse) | 80/20 to 70/30 | Higher coir for water holding in warm greenhouse conditions |
| Strawberries | 70/30 to 60/40 | Slightly more drainage to prevent root rot in dense plantings |
| Nursery stock | 60/40 to 50/50 | More air space for young roots and frequent overhead irrigation |
Irrigation method changes the answer
- Hand-watering or drip: 70/30 works for most crops. The coir holds enough water between irrigations, and the perlite prevents the mix from staying saturated.
- Ebb and flow or flood tables: 60/40 or even 50/50. The frequent flooding means the mix does not need to hold as much water between cycles.
- Sub-irrigation (wicking): 80/20 or straight coir. The system relies on the coir's capillary action, so water holding matters more than drainage.
What we supply
We supply coir-perlite mixes at 70/30, 60/40 and custom ratios, with perlite grade 3 to 4 mm and moisture under 50 percent. We can also supply straight coco peat or straight coir fibre for buyers who blend in-house.