The term geranium is confusing. The first geranium most gardeners encounter is not a geranium at all, but Pelargonium, a relative of the perennial geranium. True or hardy or perennial geraniums belong to the genus Geranium. You will sometimes see them referred to as cranesbill geraniums, because their seed pods do somewhat resemble a crane’s bill. The foliage is often toothed and remains attractive. The flowers float on top of the plant, in shades of white, pink, magenta, purples and blues.
Common Name(s): True Geranium, Hardy Geranium, Perennial Geranium, Cranesbill Geranium
USDA Hardiness Zones:
USDA Hardiness Zones 4 - 8 (Varies somewhat with species)
Varies with species, although most are low growing, from 3" to about 2' tall. They spread by rhizomes to 2-4 feet, but canbe kept in check by periodic dividing.
If grown in hot sun, provide adequate moisture.
Varies with species. Early to mid-summer, with repeat blooms throughout the growing season.
There is a great deal of variety in the geranium genus, but most of the commonly grown varieties are low growing, dense carpet-like plants. The leaves may be rounded, but more often they are serrated or lobed and quite attractive. T
The flowers are small (1") and cupped shaped, attracting plenty of butterflies and bees. Thin stems hold the flowers above the foliage. And they're deer resistant, too.
See more on the variety of true geraniums in the photo gallery Growing Hardy Geraniums.
Geraniums are wonderful when allowed to spill over edges and rock walls. They are traditionally planted under roses, to camouflage rose knees and complement the roses in color. But they look equally good paired with contrasting textures, like spiky iris or billowy astilbe.
- Geranium endressii 'Wargrave Pink' - The most commonly grown geranium. Salmon pink flowers. 18-24" tall. Zones 3-8
- 'Rozanne' - A violet blue hybrid that flowers almost non-stop throughout summer. 18-24" tall. Zones 5-8.
- 'Ann Folkard' - One of the earliest blooming geraniums, with magenta flowers that repeat bloom throughout the season. Trailing habit. 6-8" tall. Zones 5-9.
- 'Double Jewel' - Double-white petals with a lilac center. It’s short and perfect for containers. 10" tall. Zones 4-8
- Geranium oxonianum 'Southcombe Double' - Double, pure pink blooms that resemble fluffy asters. 10" tall. Zones 4-8
How to Grow Geraniums:
Geraniums require little care, once established.
They prefer full sun and a well-drained, moderately rich soil. They can handle partial shade, but become more prone to mildew if kept damp.
Geraniums are not particular about soil pH, but a neutral to slightly acid soil is ideal. (5.8 - 7.0)
Maintenance: The plants can get a bit scraggly after blooming and deadheading is difficult with so many wispy stems. Shearing the plants back to basal growth will improve its look and encourage reblooming. The plants fill back in within weeks. The exception is Geranium macrorrhizum, which is easily deadheaded and needs no shearing.
Most species of Geranium live longer if divided every 3-5 years. You can divide more frequently, so keep them from spreading. But once you see the center dying out, it is definitely time to divide.
Problems: Slugs may attack young plants. Mildew and rust can infest foliage, especially in partial shade and/or humid climates. Shearing back and disposing of the infected leaves will help.