Pots & Trays — Square Pots

Square pots exist for one reason: they tessellate. Round pots leave a gap between every four, and across a full tent floor that adds up to a serious amount of wasted space. Square pots sit flush, and in a tent the floor is your most expensive square metre.

Seven sizes, with the dimensions given

The range runs from 2 litres (13 x 13 x 17.3 cm) to 25 litres (33 x 33 x 35 cm), with 3.5, 6.5, 7, 11 and 18 in between. Every size lists its dimensions, so you can work out how many fit your bench beforehand rather than by trial. The largest is made in black anti-UV polypropylene, which matters most when it stands close under a lamp.

Every pot names its own tray

Each size states which saucer fits under it: the 7 litre under a 17.4 cm tray, the 6.5 and 7 litre under 20 cm, the 11 litre under 25 cm and the 18 and 25 litre under 29 cm. That saves measuring, and it prevents the purchase where the pot overhangs the rim. The trays themselves are under Plant Trays.

Perforated

The 7, 11 and 18 litre sizes also come with a perforated wall, for more air at the roots and faster drainage. That sits halfway between a solid pot and an airpot: you get more air without the wider footprint or the higher cost per litre. Note that the perforated versions are slightly taller than their solid counterparts, 28 against 27.8 cm at 11 litres and 31 against 30.5 at 18, which matters if you are counting millimetres under a shelf.

Propagation pots

For raising young plants there are pots of 0.7 litres (9 x 9 x 10 cm) for cuttings and just-germinated seed, and 1 litre (10.3 x 10.3 x 14 cm) to pot them on into. Exactly fifteen of the latter fit a standard 60 x 40 cm tray, five rows of three, and 81 to a square metre. That makes it the size for batches, because you know in advance how many you have.

Frequently asked questions

How many pots fit in my tent?
Divide your floor measurement by the outer size of the pot and leave an edge free to work in. With square pots that sum holds; with round ones it does not, and that is exactly the difference these pots buy.

Are the holes the same as an airpot?
No, less pronounced. A perforated wall gives more air, but the folded open wall of an airpot actively prunes the root tips. What you buy here is half the effect on an ordinary pot.

When do I pot on from propagation to final?
When the roots reach the edge of the root ball, and not later. Waiting costs more than it gains, because from that point the plant is making root with nowhere to go.