Paw paws (Asimina triloba) come from the forests of the eastern U.S. These fruiting trees grow in U.S. Department of Agriculture plant hardiness zones 5 through 9, though they often have difficulty adapting outside their native range. Several cultivars have improved fruiting characteristics. The height of paw paw trees depends on number of environmental and genetic factors
Paw paws grow naturally in the shade of large canopy trees from Michigan to the Gulf Coast of Florida. In nature, paw paws form small colonies of many individual trunks sprouting from a common root system. The mature height of the tree ranges from 10 to 40 feet, with the larger trees more likely to form where there are breaks in the canopy allowing more sunlight to the forest floor. Otherwise, the plant can maintain an almost shrubby habit, creeping along in the forest understory.
In the Yard
Seedlings planted in the yard grow as single-trunked trees and are more likely to achieve a mature height of 40 feet, especially if they are planted in full sun. The varieties that have been selected and improved for their fruiting characteristics usually grow only 15 to 20 feet tall and may be kept even smaller with annual pruning. "Mango," "Taylor," "Sunflower" and "Rebecca's Gold" are some of the varieties available.
Paw paws grow slowly when they are young and even more slowly when they are planted outside their native range. In the western parts of the country, a 10-year-old tree may have only grown to 6 or 8 feet tall. It may eventually grow to 10 or 12 feet, if it survives.
To grow, produce fruit and reach full size, paw paws need a slightly acidic, well-draining soil that is rich in organic matter. They require at least 30 inches of rainfall annually, or the equivalent from supplemental watering. Young trees need partial shade to get established. In addition, high temperatures and high humidity are the critical factors that allow paw paws to thrive. They grow poorly in both cool coastal areas and hot, arid climates, or anywhere where they are subject to drying winds.