The benefits of summer pruning
Check plants for summer drought especially pots and new plants
Deutzia setchuenensis corymbiflora
You may not associate summer with the task of pruning, most people would look on it as a winter job, but there are many plants that are pruned in the summer and it is beneficial to them. Hedges are something we do expect to summer prune and if you haven't done so then it is something that needs to done as soon as possible. Slow growing hedges like yew may suffice with one trim per year. Other hedges like privet, laurel and escallonia really benefit from twice trimming a year to keep their growth compact. Some conifer hedges like leylandii, cypress and Thuja may even need three clippings a year to keep them at their best.
Wall trained fruit trees, these are shaped trees known as cordons, espaliers and fan shaped should be summer pruned. Fruit grown as trees is best left until winter apart from the Prunus family which includes plums, cherries and peaches which can also be summer pruned if required.
Once your wall tree is established and has a main frame of old wood large enough for the space it is growing in then summer pruning is recommended. Pears around mid July and apples, plums and cherries early August. Cut back all lateral growth to two buds from the main frame. This process is done after the main growing season is over and the wood is hardening up. This allows the plant to put its energy into the existing fruit and fruit bud production. It also allows the fruit to gain as much sunlight for ripening the existing fruit.
Fruit bushes, currants and gooseberries also benefit from some summer attention. Thin out some of the new growth by cutting back to the main stems. Do this selectively to allow some strong shoots to remain to form the main structure of the plant next year. Leave all the fruiting wood at this stage and remove a third of this in the winter. These will be replaced with the strong new shoots you left previously.
Roses as we all know are deadheaded to encourage repeat flowering. I feel that in general people are too light handed with this job. All English roses, hybrid teas and florabundas are better pruned a little harder than just removing the flowering tips as many do. Cut back to five leaves and give a feed of a specific rose fertiliser. This will give better blooms second time around and keep the give bush in better a shape. Roses that are once flowered can be left alone or if for size or shaping purposes be cut back after flowering.
Climbers too can be pruned now. Honeysuckles that have flowerd can be cut back as can Clematis montana. Wistera flowers better if pruned now. Once you have the main structure of the plant the way you want it prune back all straggly new growth to 5 leave buds. This will leave plenty of foliage still. In winter these shoots can be hard pruned back to the main stems.
Summer flowering shrubs like Philadelphus ,Weigelia and some Deutzia can be selectively pruned after flowering. Remove about a third of the old flowering wood to the base of the plant. Allow a third of the new strong growth alone to replace this old wood and prune out the rest.
There is a tendency to prune trees in the summer a lot more these days. This has its thinking in the fact that the bleeding cut made at this time of year heals more quickly and stops disease and infection entering the plant. This is particularly important in reducing fungal spores entering the plant.
Prunus [cherries] trees have always been summer pruned to reduce the risk of a fungal disease call silver leaf. The bleeding of these summer cuts have been seen to have no harmful effect to trees. However Hornbeams [Carpinus] and walnuts [Juglans] can bleed so heavily that its recommended that they are left until winter to prune.