Gardening Articles: Flowers :: Perennials
by Robin M.W. Parer
Delicate, azure blue flowers bursting forth from lush, very hardy plants: These are the hardy geraniums.
The precise appeal of these often diminutive, sometimes bold charmers is tough to pin down. But it's simple from a gardener's point of view. Hardy geraniums give a lot and require very little. For instance, they grow in most climates, take shade, serve admirably as a weed-choking ground cover, and produce quantities of flowers. It is even possible to have a succession of geraniums blooming from early spring to late fall. Is it any wonder gardeners are so excited about them?
Just to be clear, I'm talking here about the plants of the genus Geranium, not those other "geraniums" -- the Pelargoniums. I apologize in advance for the name confusion, but the habit of gardeners to call those tender southern African plants "geraniums" is deeply rooted. Though both are members of the same plant family, they couldn't be more different. The Pelargoniums include common "geraniums" such as the Lady Washington geranium (P. domesticum), the ivy geranium (P. peltatum), and the scented geraniums (various species including P. capitatum and P. crispum). The effort to distinguish Pelargoniums from hardy geraniums is why you will sometimes see the latter refered to as the "true" geraniums.
There are about 500 species of geraniums world wide. They thrive on every continent -- throughout Africa, from western Europe to China, from Siberia and Alaska down the Americas to Patagonia. There are even species endemic to the Pacific Islands, including Hawaii. Some of these are available from nurseries.
Leaves of hardy geraniums are typically divided into leaflets arranged in a palm-like fashion. They range from the thumbnail-sized brown leaves of G. sessiliflorum 'Nigricans' (zones 8 to 10) to the rich mid-green dinner-plate-sized leaves of G. maderense (zones 9 to 10). You can find leaves with all sorts of quilting, veining, and blotching. Growing geraniums for their leaves alone gives valuable texture to those in-between sites that are so troublesome in the garden. Plant heights range between 5 and 36 inches.
Flowers all have five equal-sized petals. They range in size from 1/4-inch to 1-1/2 inches in diameter and can be violet, blue, pink, white, and magenta. There are no yellow or clear red geraniums. Very few flowers are "doubled" (have more than one set of petals). Although the largest flowers are not truly flamboyant and bloom is frequently sporadic rather than concentrated, there are species whose seasonal show of flowers is delightful. For example G. magnificum (zones 5 to 9) makes a five-week display of violet-blue flowers for the middle or front of a perennial border that is "magnificent" by any standard.
Where They Grow
Hardy geraniums are incredibly tough and useful garden plants. They need little care and are pest- and disease-resistant. Most are hardy to about -20°F (zone 5). Some are much more cold tolerant, and one, G. pratense, can withstand temperatures up to -50°F (zone 2).
Most are soft-stemmed, herbaceous perennials that pass the winter season in dormancy and put on new leaves in spring.