Martin,
Sorry about slow reply, saw your post and wanted to get some photos to show you..
DAS can definitely be kept in containers. I have had the following three in pots and trays in mixed conditions for the last 8- 10 yrs. Regular feeding, root pruning and repotting should keep them healthy.
The main thing to watch out for is that they do not dry out in summer, also a soaked rootball followed by a hard freeze in winter have killed some of mine over the years.
I potted mine up with very free draining mix so I could “overwater� them without too much fear they would become waterlogged. An automatic water timer works well, but fanatical vigilance could substitute. As a rough guide in high summer I equate 1 day without water as the equivalent of putting your head under water for 1 minute. So if you are away for three days… Your mileage may vary of course depending on your local conditions, we are in zone 9. Bonsai books are a good source of information on how to keep potted trees healthy.
This one has been in this pot for as long as I remember. It got diseased a couple of years ago as you can see by the scraggly bottom 2/3. It eventually recovered and is bolting now. Its way overdue for a root prune as you can see â€" it was sitting on the ground and some of them decided to venture out.
This one got moved into its tray 3 years ago and has not been touched since. Its over 10 yrs old and was in the garden centre pot that it came in for the first 8 or so years.
This one is also 10+ years old. I ignored it completely apart from automatic watering and the odd root chop/prune for the first 8 yrs then put in this tray about three years ago. It gets lots of TLC now as the shallow tray off the ground means there’s not much room for error.
Cheers
Neil