How many trees do I need?

For good fruit set cross pollination is required. You need two trees of different genetics i.e. two different named varieties. For example, planting a Peterson Shenandoah variety and Peterson Wabash variety will be good to deliver a bountiful fruit set. Be sure to plant the trees no more than 30ft. (10m) apart. There are cases when pawpaws self-pollinate, however it more the exception than the rule.