The initial training for an open centred bush tree is the same as for sweet cherry. Initial fan training is also as for other fruit trees.
Unlike sweet cherries, acid cherries bear almost all of their fruit on the growth formed the previous season. Once the tree is mature enough to fruit, the aim is to achieve a balance between one year old fruiting wood and new replacement branches. This is known as replacement pruning.
Cherries (and other stone fruit) should not be pruned during winter, to minimise the risk of infection by silver leaf or bacterial canker. Light formative pruning can be carried out in spring as the leaves start to develop, but the time to prune established acid cherry trees is in late summer.
Pruning of established bush trees
- Stimulate new growth by cutting back, in late summer, about one in four of the older fruited shoots, pruning to a younger side shoot that can replace the removed growth
- Shorten over-vigorous upright growth that crowds the centre to a suitably placed side shoot
If left un-pruned the branches will become lanky and only fruit at their ends.
Pruning of established fan-trained trees
- Thin the new shoots formed along the main branches to 5-10cm (2-4in) apart and tie the retained shoots to their supports in early summer
- Prune back branches that come out from the wall to two leaves, to keep the tree flat and allow better light penetration
- In late summer tie in the current season’s growth that will flower next year
- Cut back the fruited shoots to a suitable side branch that can replace the removed growth