Pawpaw prefers a well-drained, moderately acid (pH 5.5 to 7.0), moist soil and high organic matter content. Organic mulch is also recommended. Irrigation will be helpful to necessary depending on what part of Kansas they are grown.
In the wild, the pawpaw is an understory tree and may do better with partial shade, especially during the first 2 to 3 years. Protection from high winds is also advisable due to the large leaves. The pawpaw is a small tree that may reach 20 feet high but is less broad. Trees require cross-pollination and so at least 2 and preferably 3 different varieties should be grown. These trees are pollinated by insects other than bees such as beetles and flies and must be planted close together. Trees should be no further than 30 feet apart in order to insure good pollination.
The soil for planting should be prepared in advance of receiving the trees. Amend the soil with organic matter in the area where the trees will be planted. Do not amend just the soil from the planting hole, especially if the soil is heavy and has high clay content. If you do, you have essentially made a pot that will hold water and may drown the tree. Rather, add organic matter to the area in which the tree will be planted before digging the planting hole; at least a 10- by 10-foot square. You may want to treat the entire area where your trees will be planted. Add 2 inches of organic matter to the surface of the soil and then till in.
The planting hole should be the same depth as the root system but 2 to 3 times as wide. Pawpaws have fleshy roots and are better planted in the spring (April) rather than fall unless container grown. Container-grown plants can be planted virtually anytime.
Keep newly planted trees well watered. The soil should be moist but not waterlogged. Keep the planting area completely free of weeds or any other type of vegetation within 3 feet of the trees. Mulching is recommended.
There has been a significant amount of work done on pawpaw by Kentucky State University. You can reach their pawpaw site at http://www.pawpaw.kysu.edu/ Information on growing pawpaws is available from Peterson Pawpaws at http://www.petersonpawpaws.com Neil Peterson’s pawpaws are the result of over 25 years of research and have been widely tested. Though Neil no longer sells his varieties directly, he does list a number of nurseries that carry them.
The Kansas Forest Service (www.kansasforests.org ) has seedling trees available for sale though I would recommend getting named varieties instead if you wish to plant only a few trees. The fruit from named varieties will be of a higher quality than that from a seedling tree.
Named variety pawpaws are available from Stark Brothers (www.starkbros.com ).
The University of Missouri has a couple of different pawpaw cultivar trials. You can find results from one of these trials at http://www.centerforagroforestry.org/pubs/pawpaws.pdf (Ward Upham)