Most people think about pruning in winter, or at least they think about cutting plants back, often as some sort of punishment for plants because they have grown too much. But pruning is not just about trying to make plants smaller (winter pruning often has the opposite effect) it should be about making plants the shape we want and is often about making them grow more strongly.
In general, winter pruning will be followed by strong growth in spring and the harder you prune them, the stronger they will grow. In contrast, summer pruning, in August, will not be followed by any growth at all because most hardy plants will not make any growth following a mid-August prune. They seem programmed to know that if they were to make new growth there would not be enough days, before winter, to harden the new growth enough for it to survive winter.
This is the reason we trim beech and hornbeam hedges in August – so they remain neat for the longest possible time. And we summer prune apples and pears back to four leaves so the remaining buds have a greater chance of becoming flower buds and not vigorous growth.
My apples trees, which were planted in winter 2017/18 really struggled last year in the drought and made very little growth. So this spring I pruned them really hard to prevent any fruit formation and to stimulate growth. This has worked and they look far better this year than I dared hope.
But it is too early to ‘summer prune’ and too late to spring prune so I must get to the point.
This spring I planted two cherries and three plums in the garden. If these were apples or pears I would have pruned them at planting time (they were bare root). But you should never EVER prune plums, cherries peaches or apricots in winter when they are leafless. So my cherries had to look very odd with two or three long stems, and the plums barely better. They settled in and produced new growth at the top of the long branches and last week I had to steel myself and cut off all the new growth and a lot of the branches I had paid for! I could have done it a little earlier but there should be time for the plants to produce strong growth before the end of summer.
If I had left them as they were, they would have grown and produced several new stems at the ends of the old branches, and they did, at about 1.5m from the ground. The higher the tree and the branches, the more difficult it will be to pick the fruit and also to protect it against birds. And when you prune, if you cut out one stem, you will get three or four new stems. And what do stems make? Fruit! Formative pruning is incredibly important to get lots of branches low down so you create a sturdy framework. This is important with plums too, which can produce so many fruits they break the branches – if you did not thin the fruits when they were small.
The reason winter pruning is a no-no is that winter is when the spores of silver leaf disease (Chondrostereum purpureum) are in the air. This fungus produces tiny, lilac purple bracket like fruiting bodies on infected trees which release the spores and if you prune a healthy tree in winter you create wounds through which the spores can infect the tree. It is always a good idea to dress any wounds with a sealant after pruning, especially if the cuts are more than pencil thickness anyway. There is a badly diseased tree here at work and I ought to take a photo to show the symptoms – so come back for that. Affected trees have leaves that are distinctly silvery (who would have guessed) and they lose vigour. There is no cure and trees gradually decline until they die.
As with any pruning, use sharp secateurs and cut back to just above a bud. If the tree is rather lop-sided, cut back to a bud that faces the desired direction to start to balance it up.
As to the idea of growing cherries – I know I am taking a huge chance and I do not have high hopes. The blackbirds are bound to have most of them if I get any but I have planted a sweet red cherry and an old-fashioned white or ‘Nap’ cherry – in fact ‘Napoleon Bigarreau’. It is known as ‘Queen Anne’ in the USA. It was taken to Oregon in 1847 and renamed three years later. It is similar to the ‘Rainier’ cherry. If you have ever bought a punnet of these from M&S you will realise why it is worth the risk and expense trying to grow them. If I only get two kilos over the life of the tree it will have paid for itself!