From the early season to this point in high summer there has been a lot of potting-on and this post is about filling Air-Pot containers, together with some observations and tips based on my experience of using them.
Once the pots are properly assembled, ideally the right way up and not inside out, it is time to fill with compost / potting mix. Something water retentive that is not too free draining is good. It is very important to pack the growing medium into the container firmly, without leaving pockets of loose soil or voids. This is so water does not find quick routes to gush out of holes before it can be absorbed. Also the best development of air-pruned outward pointing roots can only be achieved if soil is filling the cones.
I have found the small 1 litre prop pots are particularly easy to under fill, perhaps because there is simply less weight of compost to compress downwards. I have often lifted a small pot to see large voids, sometimes with a slug in there leering out at me.
So now I use a round ended trowel to jab downwards and outwards. Initially loosely fill the pot about half way. The trowel can be used to jab down onto the base and into the corners. Then using the back of the trowel sideways press soil into the cones. Then the pot is filled right to the top, tamped down and the trowel again used to press soil sideways.
If you are moving a small plant into a larger container the initial partial fill and poking with the trowel is still the way to pack earth well into the bottom of the pot. After setting the small rootball in place the space around is filled and again well tamped down,; this can be done by lifting and dropping a short distance onto a solid surface, and the trowel used to work soil into space and cones. Finally I work around the very top pressing down the earth with thumbs to make sure water cannot easily sneak down through loose earth at the outside edge to a hole.
I find it helpful to insert a strip of capillary matting up through the base to act as a wick, especially in small pots which might be packed onto a large tray. This just means water can be absorbed from below if necessary. This is not how Air-Pot containers are designed to be used but together with top watering I find it works well in my grow tent and greenhouse for annuals, like tomatoes and chillies.