One of the popular flowering trees, crabapples can be grown as small trees or shrubs. Their height ranges between 6 to 50 feet and their spread is dense. Depending upon the variety grown, they can have a weeping, spreading, or a pyramidal-shaped crown. Its fruits and leaves are mostly insignificant as the fruits are extremely sour and leaves not very showy.
Opt from popular varieties, like Siberian, Japanese flowering, Sargent crabapple, etc. The tree does very well in rich, loamy, well-drained soil and full sun. The soil should be enriched with organic matter. Avoid fertilizing the first year.
Water it well during its establishment period. Post that, water as per climatic need. In fact, if your soil is well drained, then water it appropriately during droughts every two weeks. Fertilize with a nitrogen-phosphorus-potassium based fertilizer just before the onset of bloom.
There are no hard and fast rules to pruning a crabapple. However, if done incorrectly it will damage the next year's flower show. It should be pruned when young to build a strong structure and to shape it. It shoots new sprouts or suckers from the ground quite rapidly.
To keep it in shape and also to ensure that the new suckers do not eat away all the nutrients, remove all the suckers in time. Prune before spring or after the flowering season is over. If the tree has gotten too dense, prune the center to facilitate sunlight and ventilation.
Never prune in July, as flower buds for the next season begin to appear in July. Prune all dead, diseased, and damaged branches. It is important to cross prune the branches, as fully bloomed ones become heavily laded which leads to breakage.
Fire blight, leaf spot, and apple scab are diseases which can cause a significant amount of damage. Fire blight is a bacterium that turns the branches black, and apple scab is a fungus that leaves black sooty spots on leaves and fruits, eventually killing the tree.
Leaf spot and powdery mildew are other diseases that infect it. Specific insecticides and germicides are available for specific problems, but they must be used in time.