Square pot 18 liter with holes 30.5x30.5x31cm

A square growing pot of 18 litres with a perforated wall, 30.5 by 30.5 by 31 centimetres. The largest perforated size in this range.

Which substrate belongs in a pot with holes

This is the first question to answer at this size, because eighteen litres is a lot to do again if it goes wrong.

Holes in the wall work both ways. They let air in and water out, and they let loose material through as well. The finer your substrate, the more of it washes out on the first waterings. You see it as a streak of grit on your tray and as a pot that has dropped a centimetre after two weeks.

What works well: potting soil with structure, coarse coco, a mix with twenty percent or more perlite, and clay pebbles. Anything granular enough not to run through a hole the moment it gets wet.

What to avoid: fine coco pith, seed compost, or a sieved mix with no structure. It loses material and it also packs against the wall, which blocks the holes and removes the advantage you paid for.

If you do want a fine substrate, line the inside of the wall with a piece of fleece. That keeps the material in while letting air and water through. It costs you part of the effect, but your substrate stays where it belongs.

Eighteen litres with an open wall

Expect to water more often than the solid 18 litre, because evaporation happens through the side too. At 30.5 centimetres, nine fit on a square metre touching. Do not stand the pot flat on a closed surface: the base holes have to stay clear, or you keep a saturated layer at the bottom.

What the holes are not

Not air pruning. Most of the wall is solid, so roots arriving there turn and start circling after all. Roots that find a hole sometimes grow out through it, and that costs you a little at repotting.

Technical Specifications:

• Volume: 18 litres
• Dimensions: 30.5 x 30.5 x 31 cm
• Wall: perforated
• Material: plastic, black
• Base: perforated for drainage
• Shape: square, tapered

Frequently asked questions

Can I use ordinary potting soil? Yes, provided it has structure. Mix perlite through it if it is fine and dusty.

Will the substrate settle in the first weeks? A little settling is normal. More than a centimetre or two and your substrate is too fine.

What is different from the solid 18 litre? Half a centimetre of height and the perforations in the wall.

Which saucer fits under it? At this size a large catch tray is more practical than a single saucer; the square trays in this range are too small for it.