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Soil
Climate
Site
Establish
Pests
Pollinate
Harvest
Fruit

Cultural Advice (See more opera)

Soil

  • Pawpaws are flexible in their soil requirements.
  • The main thing is good drainage. The soil must be well drained.
  • Soil pH should be moderately acid to neutral, in the range of 5.5 to 7.0.
  • Pawpaws are happiest in a rich, deep, loamy soil with high organic matter content.
  • In addition, they appreciate an organic mulch. In the wild, a natural mulching layer of decomposing leaves is normally present.
  • Excessively dry sites should be avoided. Moist soils are ideal.

Climate

  • Pawpaws are native to the humid temperate climate of eastern North America.
  • They are hardy to at least -20 Fahrenheit (-28 Celsius).
  • They require a approximately 400 hours of chilling to break dormancy. This requirement varies with provenance: pawpaws of northern origin require more chilling than cultivars of southern origin.
  • Hence, pawpaws grow best in USDA Hardiness Zones 5-8. www.usna.usda.gov/Hardzone/ .
  • They need a minimum of 30 inches (~75 cm) of rainfall annually with the majority of that falling in spring and summer.
  • They need a long warm summer to ripen the fruit -- at a minimum 150 frost-free days and 2200 GDD (Growing Degree Days).

Site and Spacing

  • The pawpaw is a small tree that typically grows to about 20 feet high and less broad.
  • In an orchard setting, tree centers should be at least 10 feet apart. Row widths depend on the size of tractors and equipment -- 20 foot rows may be a minimum width.
  • When raising just a few trees for fruit, it is advisable to plant them close -- no further than 30 feet apart -- in order to ensure good pollination, as the flowers are insect pollinated and as the trees are self-infertile.
  • For good fruit production the trees should be grown in full sun. While it is true that pawpaws are shade tolerant, they will fruit much less in the shade.
  • Because of the large size of the leaves, windy sites are damaging and to be avoided.

Establishing Young Trees

  • Prepare the soil in advance of receiving your young pawpaw tree from us.
  • The soil from the hole should be thoroughly loosened to a fine tilth. The hole should be the same depth as the root system, and 2 or 3 times the diameter of the root mass.
  • In an orchard setting, we recommend you plow a furrow down the row, rototill the soil to a loose tilth, and then mound the soil into raised beds.
  • Pawpaw trees do not have fibrous roots. Their roots are fleshy, similar to magnolia. And like magnolia, pawpaws transplant better if moved in the spring, not the fall. That is why we ship our trees only in April.
  • However, container grown stock can be planted virtually anytime during the growing season. Our trees are field grown, not container grown.
  • For the first growing season keep the trees well watered. Do not overwater, however. Drowning the tree is bad.
  • Keep the area completely free of weeds & all competing vegetation up to a 2-foot radius. Weed control is essential to successful establishment.
  • Pawpaw is almost the last tree to leaf out in spring, a trait reflecting its tropical origins. The young leaves often appear chlorotic. Don't worry. This is a temporary springtime condition. Chlorosis on mature leaves is a different matter, however.

Pests

  • The pawpaw is bothered by very few pests. But like all creatures great and small it has natural predators and diseases. The primary insect pests are :
  • Talponia plummeriana, the Pawpaw Peduncle Borer, a small native moth about 5 mm long, whose larvae consume the fleshy parts of the flower and tunnel down the peduncle into the branch. This of course kills the flower. In a normal year Talponia provides a beneficial thinning action. But in a bad year Talponia can kill the entire crop.
  • Eurytides marcellus,the Zebra Swallowtail Butterfly, a butterfly of great beauty, whose larvae are obligate feeders on the tender young foliage of Asimina species. This insect almost never causes economic damage. The eggs are laid singly, the larvae are cannibalistic and are heavily parasitized. It is capable of defoliating small seedlings, however.
  • Leafspot is caused by various fungi. Sooty mold and flyspeck can mar the surface of the fruit's skin. Soil nutrient imbalances (which can result from improper soil pH) can lead to black fungus rot of the ripening fruit.
  • Slugs are reported to be a major defoliating problem in California. Slugs have not been a problem in the eastern US, however.

Pollination

  • Pawpaw trees are self-infertile, although exceptions are possible. Therefore, for good fruit set each variety must be fertilized with pollen from a different variety of pawpaw tree.
  • Pawpaw blossoms are designed by their color (purplish red) and odor (fetid) to attract their primary pollinators, various species of flies and beetles. Bees rarely, if ever, visit pawpaw flowers.
  • If natural pollination is inadequate, you may wish to attract flies to your pawpaw trees. Corwin Davis found that hanging road kill in his trees during blossom season worked well. Manure might work well. Neal never used attractants and still had good pollination.
  • Pollination is weather dependent. Cold, rainy, breezy weather is not conducive to fly (or bee) activity and can result in low fruit set.
  • Hand pollination of pawpaw is not difficult. For the backyard grower this is a feasible way to increase fruit set.

Harvesting

  • Pawpaw fruit is climacteric -- a wide class of fruits that includes apple and peach. In the course of ripening, climacteric fruits evolve carbon dioxide, water vapor, and ethylene, a plant hormone that promotes ripening. Pawpaws release large quantities of ethylene when ripening.
  • When they are ripe, pawpaw fruits naturally fall from the tree. Pawpaws may be handpicked from the tree slightly under-ripe and still proceed to finish ripen normally. If picked too early, they will not finish ripening properly or at all.
  • The signs of ripeness are subtle and not easy to discern. Visual clues are few or lacking altogether. In some cultivars the skin may turn from green to a yellowish-green, although this depends on the season and weather. A more dependable sign is a slight softening of the fruit, similar to peach.

Storing Fruit

  • Pawpaw fruits are highly perishable, comparable to raspberries. They have an active metabolism and high rate of respiration.
  • Pawpaws refrigerate well at standard refrigerator temperature. They may be stored that way for about a week if they are fully ripe. If they are underripe they may be stored for almost 3 weeks and then removed to room temperatures and finished ripening.
  • Fully ripened fruit can only hold for 2 to 3 days at room temperature. They are soft and easily bruised.
  • As the fruit goes from ripe to overripe, the skin develops brown blotches and spots and gradually darkens to an overall brown and black. In the process the flavor deepens, developing caramel tones. Some people prefer their pawpaws this way. And some swear it is the only way to eat pawpaws.

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For questions regarding pawpaws, email: neal@petersonpawpaws.com