Whether apple, sweet cherry or currant, almost all fruit trees and berry bushes depend on pollination by bees, bumblebees, hoverflies and other insects. If it is very cold in the spring during the flowering period and the insects are too slow to awaken from their winter dormancy, the pollination rate of fruit blossoms often leaves much to be desired as well. There’s little you can do about low temperatures, but you can still make sure that the aforementioned species feel comfortable in your garden and find enough food. A colorful bloom of spring flowers and native flowering shrubs such as cornelian cherry can help attract beneficial insects to the garden.
In a nutshell: How can you ensure fruit tree pollination?
Plant spring bloomers and native flowering shrubs to attract important fruit tree pollinators, such as bees, bumblebees and other insects, to the garden. Also, offer a variety of shelter options such as insect hotels and bumblebee boxes. If late frosts threaten, the sometimes early start of flowering of some fruit trees can be delayed with the help of a thick layer of mulch around the roots. Note that apples and pears require a simultaneously flowering, other variety in the vicinity for pollination, they are not self-fertile.
The pollination of fruit trees stands and falls with the weather
For insects to be able to do their job, the weather during fruit blossoming is crucial. Honey bees, as well as hoverflies, are only on the lookout for nectar at temperatures above 12 °C / 54 °F, wild bees start at 8 °C / 46 °F. Bumblebees venture out of the hive as early as 4 °C / 39 °F. They fly for up to 18 hours a day, while bees are out for a maximum of 14 hours. If you set up an insect hotel for solitary bees and hoverflies, for example, or hang up a bumblebee box, you will help the insects to become at home in your garden. Also, remember that wild bees pollinate 10 times as many flowers as honey bees.
The flowers of peaches and plums open as early as March, when the risk of late frost is still high. The beginning of flowering can be delayed if you cover the root zone with a thick layer of mulch, so that the soil warms up more slowly. An espaliered fruit on the south side of the house should also be shaded with fleece in sunny weather.
Organic tip: When frost threatens, diluted valerian flower extract sprayed into opened fruit tree blossoms can usually prevent complete crop failure.
A sprinkler set up also provides some frost protection. Devices that atomize the water particularly finely with spray nozzles are ideal. In professional fruit growing, such devices are used for so-called frost protection sprinkling: The open blossoms are encased in a thin coat of ice, which protects the frost-sensitive blossom organs from even lower temperatures.
If April brings early summer temperatures and drought, the flowering period is shortened and the trees produce less nectar. Therefore, until the beginning of flowering, you should water the root zone generously.
Apples and pears are not self-pollinating
Pollination is particularly critical for apple and pear trees: they need another variety in the vicinity that flowers at the same time, as they cannot pollinate their flowers themselves, they are not self-fertile. So, when in doubt, it makes more sense to plant two smaller apple trees than one large one, unless it has a pollinator. It’s best to find out which varieties are the best match in this regard when you buy your apple tree, because not all apple trees are good pollinators. By the way, self-pollinating fruit trees such as sour cherries or peaches are also more susceptible to foreign pollen and therefore yield better if there are two specimens in the garden. Especially for non-self-pollinating fruit trees, bumblebees are among the most important pollinators, as they change trees more often than honeybees.
Pollination of fruit trees: set up a bouquet of blossoms as a pollen donor
If a suitable pollen donor is missing, you can use a trick to ensure fertilization: simply cut a bouquet of flowering apple or pear branches and place it in a bucket of water in a sunny spot under the tree that is to be pollinated, the busy insects will take care of the rest.