The apple trees are coming into blossom. For orchard owners it can be a nerve-wracking time. Apple trees only produce fruit if they have been properly pollinated. Good weather is an important factor. Late frosts and high winds can damage the blossom. Most fruit trees are pollinated by insects, in particular bees and hoverflies. Bees tend not to venture out if it’s too cold, too windy or too wet.
But don’t despair, although poor weather can be a problem, it only requires two or three warm days while the tree is in blossom for the insects to start foraging and for pollination to take place.
Most apple varieties require pollen from a different apple variety that flowers at the same time for effective pollination to take place. Two apple trees of the same variety will not pollinate each other. To find a compatible apple variety for your tree the Royal Horticultural Society has a useful guide to flowering times and pollination groups.
A few apple trees are self-fertile, such as Granny Smith, and do not need a pollination partner. However, even self-fertile varieties will produce a superior crop, in terms of both taste and quantity, if there is a compatible cultivar nearby.
Certain cultivars, known as triploids [ see The Trouble With Triploids] which includes such well-known varieties as the Bramley, Jonagold, and Ashmeads Kernel, are self-sterile. They need to be pollinated by a compatible apple or crab apple, but will not pollinate in return as they have no viable pollen. So, if you have a triploid variety you will need at least two other trees that can pollinate each other as well as the triploid.
Crab apples make excellent pollinators for most apple varieties. They blossom over a long period of time and produce a lot of pollen. One is sufficient for a whole orchard.
It is easy to get hung up on pollination. In most gardens, even if you don’t have a room for a pollination partner, there is a good chance your tree will get pollinated. Apple trees, after all, are very common and there is a good chance there will be a compatible apple or crab apple trees growing in your neighbourhood whether you live in the town or countryside.
So relax and let the insects do the work for you. Bees – honey bees, bumblebees and solitary bees – are particularly important pollinators so anything you can do to attract and support your local bee population will certainly help.