Airpot 22.5 liter 30x30x25cm

A 22.5 litre fabric pot, 30 by 30 by 25 centimetres. The largest of the three, and the first where how you fill it matters.

Filling it without compacting it

An empty fabric pot does not stand up on its own. The temptation is therefore to press the substrate in firmly so the thing holds its shape while you carry on working. Do not.

Compacting removes precisely what you bought a fabric pot for. The air between the particles is half the story: roots need oxygen, and compacted substrate holds water in places it can no longer drain from. You turn an airy pot into a dense lump that stays wet longer than a plastic pot of the same volume.

This works better: stand the pot where it is going to live, roll the top edge outwards a little, and spoon the substrate in loosely to about five centimetres below the rim. Tap the pot on the floor a few times so it settles by itself rather than under your hands. Roll the edge back up and water gently the first time, in rounds, so the substrate wets evenly and sets itself.

Bear in mind the pot expands when full and wet. Going from 30 centimetres dry to a little more wet is normal, so leave a couple of centimetres to its neighbours and to the edge of your tray.

Roots at a porous wall

The geotextile passes air. A root tip meeting the wall dries back at the point and grows no further; the plant branches behind it. At 22.5 litres that is the difference between a ball using the whole volume and a dense collar of roots around the edge with unused substrate in the middle.

What this size is for

A little over twenty litres carries a plant grown on properly before flowering. At 30 centimetres wide you fit nine on a square metre touching, or four with room to work.

Technical Specifications:

• Volume: 22.5 litres
• Dimensions: 30 x 30 x 25 cm
• Shape: square base
• Material: porous geotextile, black
• Drainage: through base and wall
• Reusable: yes, washable

Frequently asked questions

How full should I fill it? To about five centimetres below the rim. Right to the top and it washes over when you water.

Does the substrate settle after a few weeks? A little, and that is normal. Top up with fresh material rather than pressing it down.

Can I lift it when filled? Carefully, with your hands under the base. Do not lift it by the top edge, which has nothing reinforcing it.

Which substrate suits it best? An airy mix. Add twenty percent perlite or clay pebbles if you find your soil heavy and dense.