Growth Requirements for Crabapples

Sun and Soil Preferences

• Crabapple trees flower and fruit best when positioned in an area where they receive eight to 12 hours of sun per day. They thrive in well-draining, but moist, clay loam soil or sandy clay loam soil ( with an ideal pH between 5.0 and 6.5. They will grow just fine, however, in slightly alkaline soil, and even in compacted or occasionally flooded soil.

Water and Fertilizer Requirements

• Crabapple trees are only moderately drought tolerant, requiring water during droughts of three or more weeks. Droughts will not often kill the tree but will stress it and reduce flowering and fruiting for the next year. During dry periods, water once every other week from the base of the tree out beyond its canopy to a depth of 6 to 8 inches. These trees require little fertilizer and overfertilizing can increase the risk of disease. Fertilize only if the tree's growth seems stunted or the leaves look small, with 4 cups of 10-10-10 fertilizer per 100 square feet of ground below the canopy. Sprinkle the fertilizer on the ground, keeping it away from the trunk of the tree, and water deeply to settle it into the ground.

Pruning and Maintenance

• This tree grows a strong structure on its own, resisting breakage from wind and the weight of snow. It does tend to sucker from the base of the tree, however, and grow water spouts. Prune these out in late winter or early spring. Also prune out dead, diseased, broken or crossing branches to increase air circulation in the canopy. Clean up the fruits as soon as possible after they fall, as rotting crabapples can attract pests and harbor diseases.

Pests and Diseases

• Crabapple trees are susceptible to a number of pests and diseases. Problematic diseases include apple scab, frog-eye leaf spot, fire blight, powdery mildew, canker diseases and cedar apple rust. Some cultivars contract these diseases more easily than others. To avoid many of these diseases, you can plant resistant varieties such as "Centurium" (also called Malus "Centzam"), hardy in USDA zones 4 through 8, and Sargent crabapple (Malus sargentii), hardy in USDA zones 4 through 7. Otherwise, keep the tree healthy with good watering, fertilizer, pruning and maintenance practices. Bothersome pests include aphids, fall webworm, scales, borers, mites and eastern tent caterpillars, although these rarely kill the tree. If you see nests from the caterpillars, simply prune or pull them out and destroy them. You can control scale with a smothering application of horticultural oil sprayed over them.