By Bodie Pennisi
University of Georgia
Today, cranesbill geraniums are among the hottest plants in the landscape industry, following the introduction of one called Rozanne in 2001. Rozanne cranesbill hardy geranium is so hot, in fact, that it was chosen the 2008 Georgia Gold Medal winner for herbaceous perennials.
Gardeners and landscapers throughout the Southeast are singing the praises of this exciting new plant, calling it a floral blockbuster and an exceptional performer, even in the unrelenting summer heat and humidity of the Southeast.
Rozanne grows in a well-rounded mound to a height of 18 to 20 inches. From late May until frost, the plant produces an abundance of blue-violet flowers with pale centers. Its attractive, deeply lobed foliage turns brownish red in the fall.
Plant cranesbill in well-drained, amended soil and keep in full sun to lightly shaded sites. Fertilize at planting time with a complete granular fertilizer, such as 10-10-10, 16-4-8 or 12-4-8, and repeat one to two additional times during the growing season.
The plant is a vigorous grower and is likely to decline in bloom during midsummer when the sprawling foliage competes for the plant’s energy. At that time, pruning will encourage new growth and create more flowers to brighten the fall landscape. After the first frost, cut back the plant and mulch it with leaves to provide a warm winter rest.
Use Rozanne cranesbill hardy geranium in perennial borders, rock gardens or decorative containers. The plant grows best in zones 5 to 8.
(Bodie Pennisi is a Cooperative Extension horticulturist with the University of Georgia College of Agricultural and Environmental Sciences.)