Pruning your trees is vital. Pruning at different times of the year will produce different effects. Winter pruning during the tree’s period of dormancy will cause greater growth in the forthcoming season; summer pruning causes growth to slow; spring pruning produces a combined effect. If you have planted out a one year old bare root trunk, cut off the top half of the trunk with a pair of secateurs soon after planting.
A two, three or four year old tree should have its black coloured side shoots pruned by a third between December and February – pink coloured growth from the previous year should be left untouched. Prune above an outward facing bud.
Pink growth should only be cut away if it has become diseased. Trees which are five years old are now mature, having established their shape: prune these trees to keep the centre clear, removing also growth which is weak or diseased.
Try to maintain an equal balance between growth produced in the last year – on which apples will grow – and older growth. Cordons need to be pruned in August, with side shoots pruned back to three leaves. Tie down new growth to keep a trained tree growing sideways.
To stop any over-wintering pests, use a horticultural oil-based winter wash in December or January. During the growing season you can use a lighter summer oil, and also protect from moths by applying a grease band at 50 cm above soil level. This is a sticky paper which will stop wingless moths from reaching up into the branches where they will mate and leave caterpillars to eat leaves and fruit.
It's important to keep the soil pH at 4 to 5.5, so it's worth monitoring the soil yearly, adding sulphur pellets as adjustment if it is no longer acidic. If you are growing your blueberries in pots, feed regularly with a feed high in potash.