Normally columnar apple trees are grafted to various rootstock so little info is available about what type of roots they form if grown on their own roots.
Pictured below are a group of open pollinated columnar apple seedlings, about four years old. These were grown in large pots and all normal looking seedlings (non-columnar appearance) were culled.
As you can see, the roots are quite thick and stubby just like the above ground growth.
awesome experiment!
they normally get grafted on vigorous stock. To combat their natural tendency to dwarf by “overbearing”/“spur growth”. I always wondered about them on own roots.
Out of curiosity. How long from sowing did it take till first fruits?
If you plan to keep growing them on own roots. I’m very curious how big they will get in 3-5 years. Please keep us up to date 
They haven’t flowered yet. I’m not sure if it’s due to age or due to the fact that they’ve gotten accidentally pruned by sheep a couple of times. They’d probably be just a bit bigger if they had been better protected. I actually just planted them in ground today (which is why I had the opportunity to get root pictures) so I’ll see what happens…
I actually had one more seedling that was not pictured. It was only a few inches tall despite being the same age as the others. I suspect something is going on with that one making it genetically hyper dwarf. Maybe it has two copies of the columnar gene instead of one? Not sure.
