Q What rootstock do I need for espalier apple trees?
Alison Fairwater, by email
A MM106 and M26 are bestsuited for espalier apples. M26 is good on a fertile soil, but MM106 is more vigorous and suited to a wide range of soils or where growing conditions are perhaps not so good. If you opt to grow espaliers on MM106 rootstock, you’d need a minimum of 4.5m (15ft) between the trees. On a M26 rootstock, which is more dwarfing, you need 3.3m (11ft) between trees.
Make sure the apples you choose are spur-bearers. This is usually indicated on the label. Avoid tip-bearers and partial tip-bearers, such as ‘Bramley’s Seedling’ as they’re unsuitable to grow as espaliers due to the pruning regime, although you’ll still find them offered for sale trained as espaliers. For good pollination you need to choose apples in the same pollination group, or adjacent groups. Again, this should be indicated on the label.
Although a fully-trained espalier looks very impressive, developing new ‘arms’ higher up the trunk may not always go smoothly, meaning a year is lost if a branch fails to develop in the correct place. I generally favour training apples as fans as the process is easier and there’s usually a spare shoot to train in.