American Pawpaw

Asimina Triloba

This native to North America and only cold hardy member of the custard apple family, Annonaceae, which includes the papaya and the cherimoya, was first written about by De Soto in 1541. The pawpaw was also mentioned in the chronicles of Lewis and Clarke. Thomas Jefferson thought so much of the pawpaw he planted it in his orchard at Monticello. Throughout the history of America, the pawpaw has been memorialized in songs and poems.

The pawpaw grows as a small shrubby understory tree. These deciduous, slow-growing trees generally mature at 15 to 25 feet tall with an 8 to 10 feet spread. Pawpaw goes by several common names such as Michigan Banana, Poor Man’s Banana, and False Banana. These names are derived from the fact that the fruit looks like a stubby, kidney-shaped banana 3 to 5 inches long and nearly 2 inches thick. It is the largest edible native fruit at 1/3 to 1 pound each. The fruit starts off pale green and as it ripens it will turn yellow with brown or black splotches. The egg custard-like, yellow pulp is interspersed with large flat brown or black seeds. The fruit ripen in late summer or early fall. These long-lived trees have 6 to 12 inch dark-green, elongated toothless leaves which are held in a drooping fashion. Their unusual dull purple, foul-smelling flowers have 6 petals and hang upside down.

The custard-like pulp of the pawpaw has the consistency of mashed bananas. It tastes like banana and caramel with a hint of citrus. The fresh fruit are eaten raw, used to replace bananas in recipes like banana nut bread, and to make jam. Some people like to blend the fruit with yogurt and cinnamon or eat it over ice cream. The unripe seed, fruit, and peel can be mildly toxic to some people, though sensitivity varies. Also, a few people are put off by the odd flavor and prefer the pulp cooked.

The pawpaw is hardy in zones 5 through 8 and range from the Great Lakes region to the Gulf Coastal plains and eastward to the coast. Pawpaw trees grow in the wild along riverbanks, in bottomlands, and in forests usually as a shaded secondary growth tree under taller trees. They need shade and protection from the wind the first three years of growth but produce more fruit when cultivated in full sun. They prefer deep, rich, well-drained, moist soil with a pH of 5.5 to 7. They tolerate many soil types but not waterlogged soil. Good drainage is the key to success.

Early spring or fall is the best time to plant. Plant your pawpaw tree in deeply tilled soil since they have a deep taproot and space them 8 feet apart. Container grown trees have a better survival rate than bare root trees. Keep the young trees shaded and consistently moist, but not overly wet throughout the growing season; this will reduce the possibility of transplant shock. It’s best to protect young transplants and seedlings from direct sun until they are three years old. Apply a balanced fertilizer such as a 20-20-20 liquid fertilizer every other week until early fall; this will aid in establishing the new young pawpaw trees.

Pawpaw trees are usually propagated by seed or by using budding and grafting techniques, as seeds are slow to germinate. They require a period of stratification for 70 to 100 days in a cold, moist environment. This can be accomplished by sowing the seed in late fall and letting them overwinter in the soil where they will germinate in July or August the next year. Another method is to place the seed in moist sphagnum moss stored in a plastic baggie in a refrigerator at 32 to 40 degrees Fahrenheit. Once their cold requirement is reached and they are fully stratified, the seeds can be planted. Sow the seeds in 14” to 18” deep tree pots to accommodate the long taproot. Use a well-drained soil mix and plant the seeds one inch deep. If a temperature range of 75 to 85 degrees Fahrenheit is maintained, the seeds will germinate in 2 to 3 weeks and shoots will start to appear in about 2 months. These saplings will start to produce fruit in about five to eight years.

Since cuttings have proven to be almost impossible to root, the pawpaw is generally vegetatively propagated by techniques such as chip budding, whip-and-tongue grafts, and cleft grafts. Grafted trees typically bear fruit in about 3 years.

Pawpaws are not self-fertile and are also self-incompatible, so they require pollination from a genetically different tree. Flies and beetles are the primary pollinators, but are not always dependable. So, it may be necessary to hand-pollinate your plants in order to ensure good fruit set. This can be accomplished by using a small artist’s paint brush to dab fresh pollen from the anthers of one plant to the stigma of another plant. This method is so efficient it may cause the plant to produce too much fruit. Thinning the fruit may be necessary to keep from stressing the overall health of the tree and causing limbs to break.

In their native habitat, the pawpaw is rarely troubled by any insect pests since the leaves and bark have natural insecticidal properties. The worst two insects that can cause problems are the pawpaw peduncle borer larvae and the zebra swallowtail butterfly larvae. Raccoons, deer, possums, bears, and squirrels will eat the ripe fruit and can compete for the harvest.

The fruit of the pawpaw is dark butter yellow with brown or black streaks and noticeably fragrant when ripe. It comes off easily with a quick twist or by gently shaking the tree. Unfortunately, the fruit does not store well, that is why it has never become a popular commercial food. Although it can be stored in the refrigerator for up to a week, freezing the pulp usually changes its flavor.

There are a number of new varieties that are superior to the native trees. Varieties such as ‘Sunflower’, ‘Taylor’, ‘Sweet Alice’ and ‘Davis’ are preforming well in orchards across many parts of the country.

 

References and External Links:

• Pawpaw Planting Guide, S.C. Jones & R.N. Peterson et al, Kentucky State University Cooperative Extension Program Bulletin, 1990
• Miracle-Gro Complete Guide to Vegetables, Fruits & Herbs, D. Schrock, Meredith Publishing Group, 2008
• Vegetables, Herbs & Fruit: An Illustrated Encyclopedia, M. Biggs, J. McVicar & B. Flowerdew, Firefly, 2013
• Edible and Medicinal Plants, S. Brill, Harper, 1994