Pawpaw

What it is. Pawpaw (Asimina triloba) is a small, deciduous understory tree native to eastern North America. It is also called papaw or Indiana banana, and it is considered the largest edible tree fruit native to the United States. Mature trees can reach 15 to 30 feet (457 to 914 cm) tall.

The fruit and flowers. The fruit is an edible, sweet, custard-like berry, and mature fruit has a banana custard flavor. The purplish-brown flowers open in early spring before the leaves emerge, and they are pollinated mostly by flies and beetles.

Seed first. No sowing date or sowing depth is given here. Collect seed from fresh fruit, remove all the pulp, and give it a cold, moist treatment for 90 to 120 days; seed that dries out will not germinate. Seedlings take a long time to emerge because of their long taproot, and bottom heat can speed up germination.

Pollination. Plant at least two genetically different trees, because the flowers are self-incompatible and fruit needs cross-pollination.

Site. Pawpaws produce the best fruit in full sun, though they also grow in partial shade. Shade trees under 3 feet (about 90 cm) tall during their first year, because young shoots are sensitive to full sun.

Planting. Plant in fall or spring, preferably as a dormant tree in early spring. Container-grown grafted trees transplant more successfully than wild seedlings or root suckers dug from thickets.

Time to fruit. Trees grown from seed usually fruit 5 to 8 years after planting, while grafted trees may bear in 3 to 4 years.

Establishment. Shade young trees with tree guards or shelters, and provide water when needed until they grow. Weeding is important during establishment, which may take a year or more.

Feeding and mulch. Once trees are established, an annual spring broadcast of a balanced granular fertilizer such as 10-10-10 is often enough. Mulch helps hold soil moisture and cuts down on weeds.

Suckers. Trees sucker from the roots, so remove root suckers to keep a single trunk, which grows faster and fruits sooner.

Pawpaws are generally pest-free, and their natural defense compounds make them highly resistant to many insects and diseases. Japanese beetles occasionally damage leaves, and ambrosia beetles sometimes kill stressed trees. In humid climates, bordered leaf spot causes hard black spots on leaves and fruit, though the tree is not killed. A small moth called the pawpaw peduncle borer can destroy many flowers by burrowing into flower stalks. Deer generally leave pawpaws alone.

Fruit ripens from late summer to early fall. In Iowa, it generally ripens in September, anywhere from late August to early October. Pick when the skin gives slightly under a finger squeeze, since fruit picked very firm does not ripen well. Wildlife competes for the fruit, and gloves are recommended because contact dermatitis has been known to occur.

Ripe fruit kept at room temperature lasts 3 to 5 days, and refrigerated fruit can keep up to 3 weeks. Another account puts refrigerated fruit at about 10 days. Whole fruit and pulp both freeze well, and freezing the pulp preserves it for a long time.

Don’t eat the seeds or peel; they contain compounds that cause vomiting. Don’t eat the leaves or stems. Raw fruit eaten in small amounts can cause stomach or skin irritation in some people. Wear gloves when handling and harvesting, since contact dermatitis has been reported. The pages here give no toxicity rating for cats or dogs, so check with a vet before letting pets near the tree or fallen fruit.