The Pennsylvania Horticultural Society said Wednesday that it had received a $1 million gift from William H. and Nancy G. Frederick to support the nonprofit's annual Philadelphia Flower Show.

The money from the Fredericks will be used to "expand the use and diversity of new and unusual hardy plants among major exhibitors, draw attention to the impact of climate change on Philadelphia-area gardens, and support the superior level of design in garden exhibits," the society said.

William H. Frederick is a renowned gardener and author who has been a member of the horticultural society for 60 years. Among his previous donations was an $800,000 gift four years ago to Swarthmore College's Scott Arboretum.