Air Pots (Week 13, Friday)

The polytunnel needed a tidy up, to make room for more plants, so we moved a few pots around.

We use regular plastic and terracotta pots, but more and more we use air-pots, which have some advantages over the usual pots, mainly:

• they don't have a flat, circular surface, against which the roots start circling and become pot-bound; they have the same in-out structure of egg cartons;
• where the pot walls are sticking out, the cones end in a hole; roots are funnelled into these outward cones and reach the holes where they get air-pruned: they encounter air and die back, so the plant sends out new roots in response.

Fascinating things as they are, however, plants sometimes respond to air pruning by sending shoots out of the holes, like the Deutzia in this picture.

Another advantage of air pots is they unroll open, so they are quite convenient to pot on plants without disturbing the roots.

Also, they can be rolled closed again, cleaned and reused, which we do, after keeping them a few hours in a sterilising solution.

Just out of curiosity, I have shaken clean of compost a rooted cutting that we were throwing away, and it is really amazing to see the amount and ramification of roots - they were obviously happy in the pot.

We also got a chance to make some new pots from scratch, as a new batch arrived for us to trial. It's a new size, tall and narrow, meant to contain rootstock plants.

In the pictures below you can see how it is done step by step. The pots come in sheets, which I guess are easier to transport. You can tell what the top is because the first two rows of cones do not have holes, so they work as a water-retaining rim, that allows you to water the plant (otherwise the water would flow out of the holes sideways instead of downwards towards the roots)

There is a bottom disc, which is designed as a grid so that the roots grow downwards and do not get stuck inside the pot, and a little cone at the centre directs them outwards. You place the bottom some 3 rows up, so that roots will never sit in water and rot.

Then you roll the pot closed and firm it with a screw handle. Job done!

Unpacking the pots

Bottoms 3 rows up

Roll the pot

Screw close