Pears were once the dominant fruit grown in North America. Early colonial settlements would often have pear trees. The earliest known pear orchard was reported in 1630 in Massachusetts. Pears are easily adaptable to nearly all of Pennsylvania because they tolerate a wide range of climatic conditions. The one major limiting factor for pear production is the bacterial disease known as fire blight (Erwinia amylovora (Burril)). Humid conditions favor development of this disease, which can kill pear trees.
Two types of pears are commonly grown in Pennsylvania, the traditional European types (Pyrus communis) and the Asian pears (Pyrus serotina). Both types are susceptible to fire blight. Pears, like apples, require cross-pollination to set fruit. Therefore, you must plant at least two different varieties. Asian and European pears have compatible pollen, but they often do not have sufficient overlap of bloom periods to supply pollen for one another.
Pear trees usually bloom 7 to 10 days before apples and their flowers may be killed by spring frosts. Temperatures below 28°F can severely reduce the fruit set by killing the flowers. Therefore, be sure to place pear trees in a sheltered area of the yard.