<em>Asimina triloba</em>, paw paw: to plant, to grow, to harvest

Description and botany

Native to forests and sandy riverbanks of United States and Canada, the Three-lobed pawpaw (Asimina triloba) commonly called “pawpaw” is a fruit tree belonging to family Annonaceae.

Very rare in cultivation, it is almost unknown in European gardens. Although described as exotic because of its rarity, Asimina triloba has nevertheless adapted well to temperate climates, showing excellent hardiness down to −25°C.

Genus includes six shrub species and one small tree species, Asimina triloba, which has produced a number of self-fertile varieties such as ‘Sunflower’ or ‘Prima 1216’.

Slow to establish, especially during first years, pawpaw develops from a long taproot into a small tree with a straight trunk, rarely exceeding 5 to 10 m in height, about 3 to 5 m wide at maturity. In gardens its size usually remains around 5–6 m. It has a pyramidal upright habit but can be trained as a goblet to simplify harvesting. Bark, which cracks with age, contains alkaloid substances much used in medicine. With a pleasing dark brown to greyish colour, pawpaw wood is also regarded as a semi-precious wood.

In March–April, before leaf emergence, flowers appear on thin pubescent shoots marked with fine striations. Visible in the leaf axils from the summer before opening, the flower buds, which have needed winter cold to develop well, are now ready to open. The round, slightly villous buds, set in a pubescent green-yellow calyx washed with purple, open into small pendulous bells 4–5 cm in diameter, solitary or in small clusters. They are made of six petals imbricated in threes, forming two corollas. Their rounded, symmetrical shape is reminiscent of camellia flowers. The strongly veined, crepe-like petals display a pretty chocolate-red colour tending towards claret and surround a crown of numerous yellow stamens.

Asimina triloba – botanical illustration

This nectariferous flowering lasts about six weeks. Flowers emit a very unpleasant carrion-like odour (only noticeable close up) that attracts certain pollinating insects such as flies (houseflies, dung flies), butterflies and beetles.

This delicate, exotic-looking flowering precedes fruiting. Fruiting occurs only after 3–6 years of cultivation. Most new varieties of Asimina triloba are self-fertile: a single tree is enough to produce fruit, although some varieties still require several trees to set fruit.

Fruits, called pawpaws, are large elongated oval berries, grouped in threes or sixes like a bunch of bananas, hence the other nickname “Indiana banana”. Measuring 8 to 18 cm, they resemble young green mangoes but a little more rounded and can weigh up to 400 grams. Their smooth, tender skin is green-yellow or yellow at ripeness. Their pulp is generally yellow, sometimes orange, and contains large black inedible seeds arranged in two rows, making them look like papaya flesh.

The creamy pulp has a sweet and tangy flavour reminiscent of mango, pineapple and banana. Fruits are harvested when ripe from late August to mid-October and are eaten fresh or used in juices, milkshakes, compote, ice cream, sorbet and even in some beers!

This little-known fruit tree’s deciduous foliage is also attractive. Pawpaw leafs out rather late in spring, usually in May after flowering, producing magnificent foliage that lasts until autumn. Large leaves 15–30 cm long with a short petiole are alternate, simple, obovate and pendulous like small umbrellas. Deeply veined and ending in a point, they have a crepe-like texture and are reminiscent of chestnut leaves.

Bright green at bud burst and through summer, leaves take on a lovely golden-yellow hue at first autumn chills before falling.

Pawpaw : flowers, immature fruits and ripe fruit with deliciously creamy, tangy and sweet pulp

While pawpaw does not fear severe cold (it is hardy down to −25°C), it actually benefits from it since a fairly harsh winter will promote flowering. It does, however, dislike excessively hot climates and soils that dry out in summer. For good flowering, it prefers full sun north of the Loire and partial shade if summers are very hot. It tolerates any good garden soil provided it is deep, consistently cool and well-drained, with neutral to slightly acidic pH.

It can be grown as a specimen alone at the back of a border with ericaceous plants or of course in groups in an orchard. In autumn it will look splendid alongside bushes with decorative foliage.

Pawpaw pulp is rich in vitamins A and C as well as amino acids and trace elements, while leaves contain an insecticidal substance and bark has interesting medicinal properties that are the subject of studies in cancer research.

Main species and varieties

While fewer than ten species of Asimina exist, only Asimina triloba, or pawpaw, has been the focus of selection and research, carried out exclusively in the United States. It has given rise to a few interesting self-fertile cultivars.

Most popular

Asimina triloba - Pawpaw

This is the type species! It is not self-fertile, so it is recommended to plant at least two trees to facilitate pollination. You will then enjoy its delicious fruit with mango flavour!

• Flowering time April to June
• Height at maturity 10 m

See the product sheet

Our favourites

Asimina Sunflower - Pawpaw

This pawpaw is self-fertile: a single tree is enough to produce large, very flavoursome fruits! This variety contains few pips.

• Flowering time April to June
• Height at maturity 10 m

See the product sheet

Asimina Prima 1216 - Pawpaw

A handsome, vigorous and productive variety, producing fine fruits containing few seeds. It is self-fertile, so a single tree is enough to see it fruit.

• Flowering time April to June
• Height at maturity 10 m

See the product sheet

Planting pawpaw (Asimina triloba)

Where to plant Asimina triloba or pawpaw?

Perfectly hardy, Asimina is able to withstand temperatures down to -25 °C, which ensures good resistance in all regions. However, avoid Mediterranean climate, too hot and dry in summer.

Give it a position sheltered from cold winds and spring frosts that can scorch its foliage and damage its flowers.

To flower well, plant it in full sun, or in partial shade if sun is not too intense in any good garden soil of medium fertility, neutral or preferably acidic, deep, consistently cool and well drained.

Choose location carefully because once well established, the delicate taproot of Asimina triloba does not like to be moved. As pollination is carried out mainly by flies and beetles, having manure or compost nearby is therefore recommended.

It can be planted at the back of a border with ericaceous plants and naturally finds its place in an orchard.

Asimina takes beautiful golden autumn colours

When to plant pawpaw?

To encourage root establishment, planting of Asimina is preferably carried out in February–March before budbreak, or in autumn, from September to November.

How to plant pawpaw?

Although new cultivars are mostly self-fertile, still plan to plant at least two Asimina trees nearby; fruit production will be more generous: observe spacing of 2.5 to 3 m between two Asimina triloba. Growing in a pot can be attempted, but it is not recommended because this fruit tree needs deep soil to grow and its taproot may feel too cramped.

Planting:

• Loosen soil to 80 cm in all directions
• Dig a hole 3 to 5 times wider than the rootball
• Make a gravel bed at the bottom of the planting hole
• Plant your Asimina at collar level, handling fragile roots as little as possible, in a mix of garden soil, heather soil and an addition of compost or manure
• Backfill the hole
• Firm gently
• Water copiously then regularly during first year after planting

Maintenance, pruning, care and harvest

Once established, pawpaw is, unlike many fruit trees, one of easiest to maintain. It does not tolerate dry soils well and prefers soil that retains some moisture: it needs regular watering, especially during first three years as soil must remain cool throughout summer. After 2 or 3 years, it will better withstand a short drought. Mulch the base each spring.

Over time, pawpaw tends to sucker: remove suckers regularly but above all do not hoe around its base, as its roots are fragile.

This fruit tree is not very susceptible to diseases and parasitic pests, a resistance due to insecticidal substances released by its leaves and bark which naturally repel pests.

Pawpaw pruning

Pawpaw pruning is simple and should not be drastic. It aims to keep tree at a reasonable height of 2.50 to 3.50 m to facilitate fruit harvest. Carry out in winter, from January to February:

• Using pruning shear, remove branches growing inward to open up the branches
• Prune branch tips at a slant

Goblet pruning makes fruit picking easier: with pruning shear cut the leading shoot and, over subsequent winters, distribute 5 to 6 main branches all around the trunk.

→ For further reading on the subject:  “How to train a fruit tree into a goblet shape?” 

Pawpaw branch

Harvesting fruit

Pawpaw fruit harvest runs from late summer to mid-October depending on region, once fruits are soft to the touch, easily detached from the tree and before they become too brown. Seeds are somewhat toxic and must not be eaten.

Propagation

Propagation of pawpaw is done either:

• by sowing, a method that requires patience because seeds need a long stratification, root development is very slow and roots may take several years to appear,
• by grafting, using a fairly specific technique that requires some technical skill.

You can also take the suckers that develop around mother plant, but you will have to wait up to 8 years to see them flower.

We recommend buying new young plants instead.

Associate

Asimina triloba (trilobed pawpaw) offers two seasons of ornamental interest: in spring, when covered in purple flowers and bright green foliage, and in autumn when its leaves turn golden yellow and its ripe fruits give it a tropical look. It will thrive in any exotic garden!

In spring, plant around its base spring bulbs such as muscari, scilla and botanical tulips, in mauve–purple harmonies. Groundcover perennials such as bergenias, creeping bugle and heucheras will take over after flowering and keep its roots cool all summer.

An autumn planting idea: Asimina triloba, with a sea of Rudbeckia subtomentosa ‘Little Henry’ and Miscanthus sinensis ‘Little Miss’ in front of it in the sun. If you want a bit of contrast, add a purple-leaved Cotinus.

Asimina triloba can also find a place in a heather soil bed, alongside flowering bushes or bushes with evergreen foliage such as camellias, Chinese and Japanese azaleas, rhododendrons, Japanese andromedas and Cornus.

In autumn, its leaves with golden blaze will complement cotoneasters or other ornamental fruit trees such as amelanchiers, callicarpa and the fine leaf colours of Cotinus, acers, a katsura tree, a scarlet oak, Japanese cornels or even a spindle.