Trees are easily grown from seed.
It is easiest to simply plant an entire fruit in the ground or place a seed in the ground immediately upon eating the fruit.
Seeds should not be dried out, as they  lose viability if they dehydrate to 5% moisture.
The seeds need to be stratified by moist cold storage for 60-100 days at 35–45 °F (2–7 °C) (some publications suggest 90-120 days).
They will lose their viability if stored for 3 years or more; some seeds survive if stored for 2 years.
Germination is hypogeal and cotyledons remain within the seed coat.
Strictly speaking, hypogeal means the cotyledons stay in the soil, acting as a food store for the seedling until the plumule emerges from the soil on the epicotyl or true stem.
However, pawpaw seeds have occasionally been observed to emerge from the ground and form the true stem and plumule above ground.

Propagation using cuttings has generally not been successful.

Desirable cultivars are propagated by chip budding or whip grafting onto a root stock.
Pawpaw seeds do not grow "true to type" — each individual seed in a fruit is genetically different from the others and from its parent tree.
Purchased cultivars do not produce seeds true to type, either, which is why cultivars are all grafted trees.
Root sucker seedlings, however, are all genetically identical to their host.

Commercial nurseries usually ship seedlings in containers, usually grafted cultivars, but other nurseries such as the Kentucky Division of Forestry ship bareroot seedlings for reforestation projects and area homeowners.

Harvesting seedlings from the forest floor is tricky because most forest-floor seedlings are actually root suckers with few roots, and those seedlings that did grow from a seed have deep taproots.

Blowflies, such as C. vomitoria, are known pollinators of these plants.
Trees are easily grown from seed. It is easiest to simply plant an entire fruit in the ground or place a seed in the ground immediately upon eating the fruit. Seeds should not be dried out, as they  lose viability if they dehydrate to 5% moisture. The seeds need to be stratified by moist cold storage for 60-100 days at 35–45 °F (2–7 °C) (some publications suggest 90-120 days). They will lose their viability if stored for 3 years or more; some seeds survive if stored for 2 years. Germination is hypogeal and cotyledons remain within the seed coat. Strictly speaking, hypogeal means the cotyledons stay in the soil, acting as a food store for the seedling until the plumule emerges from the soil on the epicotyl or true stem. However, pawpaw seeds have occasionally been observed to emerge from the ground and form the true stem and plumule above ground.
Propagation using cuttings has generally not been successful. 
Desirable cultivars are propagated by chip budding or whip grafting onto a root stock. Pawpaw seeds do not grow "true to type" — each individual seed in a fruit is genetically different from the others and from its parent tree. Purchased cultivars do not produce seeds true to type, either, which is why cultivars are all grafted trees. Root sucker seedlings, however, are all genetically identical to their host.
Commercial nurseries usually ship seedlings in containers, usually grafted cultivars, but other nurseries such as the Kentucky Division of Forestry ship bareroot seedlings for reforestation projects and area homeowners.
Harvesting seedlings from the forest floor is tricky because most forest-floor seedlings are actually root suckers with few roots, and those seedlings that did grow from a seed have deep taproots.
Blowflies, such as C. vomitoria, are known pollinators of these plants.
Asimina triloba