Cherry trees are among the most vigorous growing fruit trees in the garden. Therefore, to slow down growth and increase fruitfulness, you should prune your cherry tree at the right time.
Cherry trees display vigorous growth and can easily reach ten to twelve meters in width when they grow old. Especially sweet cherries grafted on seedling rootstocks are extremely vigorous. Sour cherries grow somewhat more slowly, but like sweet cherries, they must be pruned regularly to ensure consistently high yields.
This is how to prune a cherry tree
Pruning a cherry tree: The right time
Pruning in the summer has proven equally effective for sweet cherry and sour cherry. For several reasons: Pruning during the growing season slows the vigorous growth of your cherry tree. At the same time, thinning pruning increases fruitfulness by allowing longer young fruit shoots to form, which will produce new cherries the following year. In addition, pruning wounds heal faster in the summer and are less susceptible to bacterial and fungal attack. Many fruit growers follow a simple rule: what can be removed with pruning shears is cut in summer or late winter, all thicker branches only in summer. For this, one then uses a pruning saw or loppers as a tool, depending on the branch thickness. This rule applies equally to sweet and sour cherries. A good time for summer pruning is right after harvest. Advantage: You can prune the early to medium-early varieties before St. John’s Day (June 23) and thus before the second annual shoot. The cherry tree thus forms longer new shoots after pruning in the same year.
How to cut a sweet cherry
Most flower buds appear in the sweet cherry, as a rule, on the two- to three-year-old shoots. If these do not receive enough light, they hardly form any fruit and also bear only a few leaves. Thus, without regular pruning, the fruiting shoots move further and further to the edge of the crown, while the tree becomes visibly bare inside the crown. The most important pruning measure for older sweet cherries is therefore thinning out the crown.
First, remove all side shoots that are growing into the interior of the crown. Then cut back all strong, heavily branched branches with over-aged fruiting wood. It is best to cut them off above a young side shoot so that it can replace the fruit branch that has been removed. Younger branches with so-called bouquet shoots should be preserved as much as possible. The short, whorled side branches are very fertile and later bear many flower buds. If individual bouquet shoots grow relatively steeply upwards and develop into competing shoots, however, you must remove the interfering ones.
How to cut a sour cherry
How to prune a sour cherry depends mainly on the variety. There are two different types of trees or growth types: The morello cherry growth type and the sour or rock cherry growth type. Morello cherries and similar varieties bear their cherries only on the previous year’s shoots. They tend to form so-called whip shoots. They form if you do not cut off the harvested shoots or at least shorten them. Whip shoots are often very long, droop heavily, and bear leaves and branching only at the shoot ends. Sprouting becomes weaker every year, takes place only on the upper shoot sections of the sour cherries and also yields only a correspondingly small amount of new fruiting wood.
Sour cherries of the morello type are best pruned immediately after the cherries are harvested, shortening all harvested branches to encourage the formation of strong new fruit shoots, or removing them altogether, depending on how dense they are. In principle, as with all cherries, more severe pruning into the perennial wood is possible and advisable for a sour cherry of this growth type if the crown is only weakly branched.
The sour cherry (Mahaleb cherry or rock cherry) growth type has similar fruiting behavior to sweet cherries. Some varieties also form short fruit whorls on the two- to three-year-old branches, although not quite as distinctly as in the sweet cherries. These cherry trees should therefore be pruned in the same way as sweet cherries: make sure that the crown is loose and well exposed and remove the worn fruiting wood by diverting the shoots to a young, favorably positioned side shoot.
Rejuvenate an old cherry tree
How much you need to prune your cherry tree depends not least on the grafting rootstock. It controls the growth of the cherry tree. If you buy a tree with a specially bred, low-growing rootstock, it will hardly grow taller than three to four meters (9 to 12 ft), even when old. A small-growing tree also has the advantage that it produces a uniformly high harvest and you can pick the cherries without a long ladder. It also takes up little space in the garden and pruning is not as time-consuming.
A sweet cherry grafted on a seedling rootstock becomes a real giant. In orchard meadows, older cherry trees that have grown for several years without pruning are therefore often pruned very roughly: the orchardists cut back the leading branches of the crown above a flatter, outward-growing side shoot to arm-thick stubs and also thin out the side branches and twigs considerably. The tree then has a loose, well-lit crown again, is much stockier and thus easier to harvest.
Is wound closure for cherry trees recommended after pruning?
Although it is often recommended to close the cut wounds, more and more professional tree caretakers do not do this. After pruning, experts usually only seal the larger wounds (larger than 1.5 cm / 0.6 in), and only the outer edge of the wound with the dividing tissue, which lies directly under the bark. The body of the wood, on the other hand, should not be sealed, as moisture often forms under the wound closure after a few years and the wood then begins to rot. Proper care of the saw wounds, on the other hand, is important: cut the frayed bark smooth with a knife so that the wound heals more quickly and bacteria or wood-destroying fungi cannot take hold.