Size is not the only thing that determines whether a fruit tree will bear fruit. Nurseries usually sell fruit tree seedlings that are 1 or 2 years old. Once a nursery seedling is old enough to produce blossoms, it will bear fruit. Exactly how large a fruit tree is to produce blossoms and yield fruit depends on the kind of fruit, the health of the tree, whether it receives sufficient pollen, the weather and the care it receives.
Age of Tree
If they receive pollen and are not held back by the weather, standard-sized apple and apricot nursery seedlings will usually bear fruit from 2 to 5 years after they are planted. Sour cherries take three to five years, and sweet cherries take five to seven years to grow. Peach and pear trees take four to six years. Quince trees take five to six years to produce fruit. Dwarf varieties can produce fruit a year or more earlier. Dwarf trees grow 8 to 15 feet tall. Semi-dwarf trees, which also bear fruit early, grow from 12 to 20 feet tall.
Most fruit trees will bear earlier if they receive adequate sunlight and space for their roots to spread. They will bear fruit later if they are planted close to other trees or large shrubs, forcing them to compete for water and shrubs. Trees that are properly fertilized will grow more vigorously and yield fruit earlier.
Fungi can attack the blossoms of apricot, peach and plum trees, preventing them from yielding fruit. If trees are subjected to chronic fungal infection, the onset of fruit may be delayed. Fungi do not discriminate according to the size of the tree, and it can strike both young and older trees.
Trees that produce blossoms are old enough to bear fruit, but unless the flowers are pollinated, they won't yield fruit. The more blossoms that receive pollen, the more fruit a tree will bear. Some trees have "perfect" blossoms, meaning they contain both the male anthers that produce pollen and the female pistols that receive pollen and develop into fruit. Apricots, sour cherries, most peaches and European plums have perfect flowers and don't need pollen from other trees to produce fruit.
Apple, Japanese and American plum trees, pear trees and sweet cherries have perfect flowers but still require pollen from a nearby tree of another varieties. Two fruit trees requiring pollen from a similar tree must produce pollen at the same time to bear fruit.
No matter how large a tree is, if its flowers are not pollinated, it won't bear fruit.
Many fruit trees need spring weather following cold winter dormancy to blossom. Mild winters can cause slow, delayed or irregular spring growth. If spring blooming is extended, then a late frost kills the developing buds. Extended warm periods in the winter may cause cherries, peaches, plums and nectarines to lose their "cold hardiness," or their ability to withstand cold. Most fruit trees will fail to bear fruit if their blossoms open and the temperature drops below 24 degrees Fahrenheit.