What: Geranium “Gerwat” Rozanne is a relatively new but outstanding hardy geranium. It is noted for its long bloom time — from June until frost in some areas — producing many large, clear blue flowers with white centers. These rise above the leaves to about 15 inches high. The foliage of Rozanne forms a tidy mound to about 10 inches high and 18 inches wide. Use it at the front of a perennial or mixed shrub border, over a large rock wall or between boulders. Grow it in a container with other perennials. Combine it with grasses, sedums, astrantias and eryngiums.
This hybrid geranium was discovered in 1990 by George and Rozanne Waterer of Somerset, England in their garden. The seed parent was geranium wallichianum “Buxtons Variety” and the pollen parent was possibly an unnamed cultivar of Geranium himalayense. In 2000, a commercial horticultural company in the U.K. introduced geranium Rozanne and the Perennial Plant Association declared it the 2008 Plant of the Year.
While typically known by its trademark name, Rozanne, its cultivar name, “Gerwat,” is used for the U.S. Plant Patent and the Plant Breeders Rights in Europe. The first part of the cultivar name, “Ger,” comes from the first three letters of “geranium” while the last three letters were taken from the originator’s name, Waterer.
Size: The spreading perennial grows to be 1 foot 6 inches tall and 1 foot 2 inches wide when mature.
Where: This hardy geranium prefers full sun but tolerates light or open shade with rich, moist to well-drained soils. Cut it to the ground in late fall or early winter. This vigorous grower can be divided every three to four years in late winter to early spring.
Water: For the longest flowering and best bloom, provide regular watering during prolonged dry spells.
— Richie Steffen, Great Plant Picks
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