We grow Birch trees, but as they have been only going for a quid or two at the sales I have kept most of last year's sellable ones in pots for another year. Mine are in old buckets at the moment, about 15L in size, and most of them are between 5 and 7 foot tall.

Even much larger ones have done well in 15L pots, but they never look as good as the same sized ones we have growing in our hedgerows.

What I would suggest for you is to plant it out in the garden and prune away to your hearts content each winter - you will easily stunt the growth yet still have a gorgous, twisted, open canopy that can be basically any size you wish.

Having seen the ones at Hickstead showjumping arena, I have been lopping branches off out 8 foot tall birches for the past two winters to keep them bonsai style, all twisted and easy to look at the view through. It works well. They may eventually grow to 20 or so feet, but that'll take years and they look fantastic in the mean time. The bark at this time of year is to die for!

I keep reading that they lose sap if pruned, but haven't found this a problem. They are also host to about 350 insects, which is a good thing. We feed them with a 6 inch layer of rotted horse muck each winter, but they really don't need it.

In the pots they dry out too quickly, even plunged in soil, and blow about a good deal.

Hope this helps. Birches are a favourite of mine.