Title image above is copyright © Kristi Ellinopoullos

First published 2nd October 2025

Some years past I set aside two young Japanese maples, each in a 4.1 L Air-Pot Small Seed Tray, to grow on to bonsai. (The bonsai training pot equivalent wasn’t a thing then).

The roots of some species will go straight through the base if allowed to (and I say this in the assembly sheet I send out), so I did from time to time lift each container to ensure the roots were behaving themselves. Until, of course, busyness got in the way, I did this less and less often, vine growth obscured the ground, and to nobody’s surprise, this was the inevitable result (photos taken after clearing a lot of overgrowth):


Japanese Maple (Acer palmatum)
copyright © Kristi Ellinopoullos


Japanese Maple (Acer palmatum)
copyright © Kristi Ellinopoullos


Japanese Maple (Acer palmatum)
copyright © Kristi Ellinopoullos


Japanese Maple (Acer palmatum)
copyright © Kristi Ellinopoullos


Japanese Maple (Acer palmatum)
copyright © Kristi Ellinopoullos

You can see how much potting mix has fallen through too, which filled the space between the bases and ground surface, and only encouraged even more root growth through the bases. The bases had long stopped being root-pruning barriers!

What a mess! These photos were taken early September 2025, and as buds were going to burst soon it became a high priority to dig them out before this too caused even more problems later.

There was no way of getting around them suffering immense root damage, and to complicate things, I didn't want to lose the heights of the trees either, as I wanted to do some air-layering on them.

I don’t ask for much do I?!

It was a particularly warm afternoon (of course) and so I prepared a massive tub of water ahead of time in which to sit each tree, and hacked away. The extracted roots of the taller tree would end up just fitting into a 38 L Air-Pot, and the smaller one would just fit into the same-diameter, less tall 16.5 L Air-Pot Bonsai training pot.

I made up enough potting medium for these two sizes while both trees’ roots remained protected and immersed in water the whole time — there was no rush now and I wasn’t going to attempt removing those bases just yet either.

The medium was made with those butchered roots in mind: two parts compost to one part fine coir. I wanted a nutritious yet slow-release mix of very high adsorption, to retain as much water and plant starter solution as possible to help those roots re-establish themselves.

After potting I drenched these two with as much pant starter solution as each container could hold (pro tip - have the peripheral medium just below the rim of each Air-Pot so that water flows into the small depression created, rather than runs over the edge taking that medium with it).

Both trees were potted still with the original bases attached! The one in the 38 L container was fully buried, but the one in the bonsai container is somewhat obvious!


Japanese Maple (Acer palmatum)
copyright © Kristi Ellinopoullos


Japanese Maple (Acer palmatum)
copyright © Kristi Ellinopoullos


Japanese Maple (Acer palmatum)
copyright © Kristi Ellinopoullos

I definitely gave each tree some more plant starter solution the next morning, but can’t recall if I did this a second morning. I did keep the water to them every day to help them settle and continued right through bud burst and leaf development. I eased off once it became very clear that these trees were completely unphased by their treatment, and they now get watered as any other trees in pots here.

These trees were uprooted on the 3rd September 2025, and today, pretty much a month later on the 2nd October, you can see how leafy they now are:


Japanese Maple (Acer palmatum)
copyright © Kristi Ellinopoullos


Japanese Maple (Acer palmatum)
copyright © Kristi Ellinopoullos


Japanese Maple (Acer palmatum)
copyright © Kristi Ellinopoullos

So boys and girls, please don’t do this at home! The best places for an Air-Pot are those that roots can’t penetrate, such as concrete, decking, metal shelves, elevated pallets, you get the idea. But if you do place an Air-Pot on soil or grass — even weedmat won’t always be an effective barrier — ,please do inspect the undersides regularly, and trim dangling roots religiously. The larger containers will be difficult to lift, but are very easy to tilt, with one person taking the weight and the other trimming the underside.