Apple trees are a staple in many people's home gardens and orchards due to the fruit that they produce. They are also known for their beautiful blossoms. However, sometimes apple trees fail to produce blossoms for several reasons that can be traced to natural causes or an oversight in their care.
Apple trees must mature before they will develop blossoms. While some varieties of apple trees will fully mature in three to five years, others take longer. As an example, Northern Spy apple trees take a full 15 years before they are mature enough to produce blossoms and bear fruit, while McIntosh and Gravenstein apple trees are ready within three to five years.
Apple trees require cross-pollination between at least two different varieties of apple trees to produce blooms and bear fruit. Some varieties produce sterile pollen and require at least two other varieties to produce blossoms and fruit; crab apples are a variety of sterile apple trees. Plant apple trees at least 30 m (100 feet) from each other to allow bees and other insects to facilitate cross-pollination.
When well-meaning apple tree growers over fertilise their trees, it promotes vegetative growth over reproductive growth. This results in trees with plenty of lush foliage and longer shoots, but fewer blossoms and less fruit. Adding fertiliser to the soil should only be based on soil tests and the tree's annual shoot growth. An apple tree that is bearing fruit usually sees growth of 30 to 45 cm (12 to 18 inches) each year, while a non-fruit-bearing tree grows 45 to 75 cm (18 to 30 inches) a year. Any growth over these amounts is usually a result of excessive fertilising. If your apple trees have less growth, increase the nitrogen-based fertiliser by 25 per cent the following spring.
Errors in pruning
Errors in pruning are one of the main reasons an apple tree does not bloom. When done properly, pruning allows the tree to keep its shape and size as well as allow for a greater amount of light to penetrate into the depths of the tree's canopy. Excessive or improperly done pruning will create an excessive amount of vegetative growth and low amounts of blooms. Pruning should be done lightly in the winter and concentrated on thinning branches down to where they meet the main trunk of the tree. Removing only part of a branch will cause excessive vegetation and lack of blooms and should be avoided.