The pawpaw is a fruit tree that is native to North America and can be found growing primarily in hardwood forests. It is prized for its unusual fruit, the flavor of which has been compared to a cross between banana, pineapple and mango. While it is best to grow pawpaw trees from grafted seedlings to ensure healthy and productive plants, they can be propagated from seed.
Tree grows to between 15 and 20 feet across and can grow to 30 feet tall. The leaves of the tree are oblong, slightly pointed and up to 12 inches long. The flowers are purple and around two inches long. The fruit grows in clusters and resembles a short, chubby, greenish-brown banana that has a custardy texture when ripe and contains the seeds of the plant.
Each pawpaw fruit holds between 10 and 14 seeds, in two rows down either side of the center of the fruit. The seeds are brown to black in color, around 1/2 to 1 1/2 inch in length, and have a shape that resembles a lima bean.
Pawpaw seeds requires a certain amount of time at cold temperatures to germinate. This is referred to as breaking dormancy. To accomplish this, the seeds need to be stratified, or exposed to a cold environment for between 90 and 120 days. The easiest way to stratify seeds is to place them in a zip-top plastic bag along with some moist sphagnum moss and keep them in a refrigerator. Stratification can also be done by planting seeds outdoors in the fall and allowing them to over-winter and germinate in late summer.
Once stratification is completed in the refrigerator, the seeds can be planted. It is best to plant indoors to control the growing conditions. Germination usually takes around seven weeks. The seeds of pawpaw trees are hypogeal. This means that when each seed sprouts, it will not produce cotyledons, the simple seed leaves typical of many other plants. It will, instead, produce a shoot first, which will eventually grow true leaves.
Because pawpaw trees are not able to pollinate themselves, the seeds of at least two different pawpaw cultivars should be planted. This will ensure proper pollination and a good fruit crop.