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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