Airpot 12.5 liter 25x25x20cm

A 12.5 litre fabric pot, 25 by 25 by 20 centimetres. The middle size: wider than the 5.8 litre cube and two centimetres lower at the same time, because the volume here sits in the footprint.

How many litres does a plant need

This is the question the whole category turns on and almost no product page answers. There is no exact figure, but there is a usable rule of thumb: reckon on around ten litres of substrate for a plant given a normal growth phase, and more the longer you grow it on.

Twelve and a half litres sits right on that mark. It is enough for one plant through a full cycle without repotting, and small enough to stand sixteen of them on a square metre.

Both ways of getting it wrong cost you something, and it helps to know what.

Too small shows up in your watering, not in the plant. Once the root ball fills the pot, less water fits per watering and you have to come back more often. Eventually you are watering twice a day and the plant still wilts in between. The crop is not ruined, but your work has doubled.

Too large shows up at the start instead. A young plant in a thirty litre pot uses a small part of that volume; the rest stays wet for weeks because no roots are drinking it down. Wet substrate with no roots in it is where root rot and fungus gnats begin. If you do start large, water only around the ball early on.

Roots at a porous wall

The fabric passes air, so a root tip meeting the wall dries back and stops. The plant branches behind it and fills the substrate evenly, instead of circling against a smooth wall.

Technical Specifications:

• Volume: 12.5 litres
• Dimensions: 25 x 25 x 20 cm
• Footprint: 625 cm²
• Material: porous geotextile, black
• Drainage: through base and wall
• Reusable: yes, washable

Frequently asked questions

How many fit on a square metre? Sixteen touching, nine with working room between them.

How much water per watering? Two to two and a half litres, until a little runs out of the bottom.

Can I put two plants in it? You can, but they compete for the same water and feed. One plant per pot gives a more predictable result.

What is the difference from the 22.5 litre? Ten litres more substrate on a footprint only five centimetres wider. What you mainly gain is depth and buffer.