Growing on rootstocks
Although fruit trees can be grown on their own roots, they are more often than not grafted onto a chosen rootstock.
The rootstock will control the rate of growth of the tree, so you can choose a rootstock to produce a tree suitable for the position you are planning on growing it in.
You can choose from those that produce large trees (better for standards) that are classed as vigorous, to those that produce much smaller trees (more suitable for training as a bush or even growing in containerts) called dwarfing. Soil type also influences growth rate, with light sandy or chalky soils limiting growth more than clay-based ones.
As well as controlling height, a rootstock will also ensure that the tree comes into fruiting earlier in its life than if it was grown on its own roots.
Apples
There are many different rootstocks available for apples. The most widely available apple rootstocks are M27, M9 and M26, and M106, producing trees of between 1.5-1.8m (5-6ft), 2.4-3.6m (8-12ft) and 3.6-5.4m (12-18ft) tall respectively.
Pears
Quince A is the most common rootstock for pears and will produce a tree between 3-6m (10-20ft). Quince C is less common and produces a tree growing to 3-5m (10-16ft). Pears on Quince C are slightly quicker to produce fruit.
Plums & gages
There are a couple of different rootstocks for plums. ‘Pixy’ is semi-dwarfing, ideal for pyramids and fans; ‘Ferlenain’ is similar to Pixy; ‘St Julien A’ is semi-vigorous, useful for larger pyramids and fans; and ‘Brompton’ is vigorous, and used for standards and generally produces a tree up to 6m (20ft) tall.
Cherries
The most commonly used rootstock for cherries is the semi-vigorous Colt, which will restrict growth to about 6-8m (20-27ft). Semi-dwarfing rootstocks Gisela 5 and Tabel will restrict the size to about 3-4m (10-13ft) making them suitable for growing as dwarf bush trees or possibly in a container.