University of Vermont Extension 
Department of Plant and Soil Science

Summer News Article

 
ROZANNE PERENNIAL GERANIUM

Dr. Leonard Perry, Extension Professor
University of Vermont
 

Each year the Perennial Plant Association, the professional organization of growers and designers, names a plant of the year. This is either a new plant, or one they feel deserves wider use, and grows well in most areas of the country.  For 2008, the perennial geranium Rozanne has been voted as the Perennial Plant of the Year.  This hardy perennial has a long and attractive bloom period, and is very low maintenance.

Rozanne geranium is perennial, so is quite different from the annual geraniums most are familiar with.  It has many iridescent blue flowers, with pink tones and white centers, in midsummer and repeating until fall in cool climates.  Flowers are about two and a half inches wide, and have five petals.

The flowers are on top of low, bushy plants that reach about 18 inches high, and about the same or more wide, in a couple of years.  This plant is great from its flowering, low maintenance requiring little care, and no serious pests or diseases.  This plant seldom needs dividing.  If it is spreading more than desired, shear back the side branches.  Cutting back to about three inches high after bloom will promote a tighter habit and bushier plant, and perhaps even more rebloom. You can cut back the stems after leaves have died back in late fall, or wait and cut back in early spring.

Leaves have a generally circular outline with five lobes.  They are about one to two inches wide, slightly dark-marbled, and turn a reddish brown in the fall.

This perennial geranium really needs full sun to bloom best.  Grow it in a moist, well-drained soil.  It will tolerate some drought once established, but grows larger in moist soils. Plenty of organic matter in soils, such as from compost or peat moss, will help it thrive.

Although often found listed to USDA hardiness zone 5, it has proven quite hardy for me over several years in USDA zone 4 (average annual minimum temperature of –20 to –30 degrees F).  If it is in a cold pocket with little snow cover, you may wish to add a couple inches of mulch or compost around plants in the fall.

Rozanne is named for one of the owners of the garden in which it was found in 1989 in England, Rozanne Waterer.  It is a natural hybrid of the cultivar ‘Buxtons Variety’ (Geranium wallichianum) and the Himalayian geranium (Geranium himalayense).   It was first introduced in England at the Chelsea flower show by Blooms of Bressingham in 2000, later making it to the U.S.  It is similar to a few other cultivars such as Buxton’s Variety, but has better heat tolerance, larger flowers, and longer bloom.  

Rozanne perennial geranium is nice in fronts of borders, used in masses as a groundcover, or in large rock gardens.  Try it in front of roses, or filling in between daylilies, New England asters, blue stars, tall garden phlox, and other tall clumping perennials.  I find a mass, interplanted with daffodils, quite effective.  As the daffodil foliage dies back in early summer, it is hidden by the emerging stems of the perennial geranium.  

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