How to Grow True Perennial Geraniums

Geranium 'Rozanne'
Geranium 'Rozanne' blooms just about non-stop, well into fall. Marie Iannotti

Looking for a geranium plant can be confusing. The first geranium most gardeners encounter is not a geranium at all, but Pelargonium, a relative of the perennial geranium that is being profiled here. Geraniums that belong to the genus Geranium are referred to as true geraniums, hardy geraniums, or perennial geraniums. You will also sometimes see them referred to as cranesbill geraniums because their seed pods do somewhat resemble a crane’s bill.

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 with flower stalks that poke and weave through neighboring plants. The flowers float on top of the plant, in shades of white, pink, magenta, purples, and blues. The flowers are small (1 inch) and cupped shaped, attracting plenty of butterflies and bees.

Thin stems hold the flowers above the foliage. The leaves may be rounded, but more often they are serrated or lobed and quite attractive. And they are deer resistant, too.

  • Botanical Name: Geranium species
  • Common Names: True Geranium, Hardy Geranium, Perennial Geranium, Cranesbill Geranium

USDA Hardiness Zones and Sun Exposure

There is some variance in hardiness among the different types of geraniums, but most are perennial in USDA Hardiness Zones 4 - 8. 

For the best flowering and most vigorous geranium plants, site them in full sun to partial shade. If grown in hot, full sun, provide regular water.

Mature Size

Most true geraniums are low growing, from 3 inches tall to about 2 ft. tall. The flowers are held above the foliage, which gives them most of their height. Perennial geraniums can spread 2 - 4 ft. by rhizomes, but they are not aggressive and can be kept in check by periodic dividing.

Bloom Period

A few perennial geraniums bloom just once, usually early in the season. Most will start blooming in mid-summer and repeat bloom sporadically throughout the growing season. Newer varieties, like 'Rozanne', bloom non-stop all summer.

geranium 'rozanne', close up of purple flower, october norfolk
Geranium 'Rozanne'. Neil Holmes / Getty Images

Design Suggestions for Hardy Geraniums

Geraniums are wonderful when allowed to spill over edges and rock walls. They are traditionally planted under roses, to camouflage rose knees, those leafless stems at the bottom of the rose bush, and complement the roses in color. But they look equally good paired with contrasting textures, like spiky iris or billowy astilbe.

Look for some of the newer hybrids, if you want season-long bloom. 'Rozanne' was the first fuss-free, profuse bloomer, and it has been used to breed more stunners such as: 'Azure Rush’, with lighter blue flowers, and 'Lilac Ice’, which has more white in the flowers against brilliant green foliage.

Irises and Geraniums in Border
Clay Perry / Getty Images

Suggested Geranium Varieties to Grow

  • Geranium endressii 'Wargrave Pink' - The most commonly grown geranium. Salmon pink flowers. 18-24 inches tall. Zones 3-8
  • 'Rozanne' - A violet-blue hybrid that flowers almost non-stop throughout summer. 18-24 inches 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 inches tall. Zones 5-9.
  • 'Double Jewel' - Double-white petals with a lilac center. It’s short and perfect for containers. 10 inches tall. Zones 4-8
  • Geranium oxonianum 'Southcombe Double' - Double, pure pink blooms that resemble fluffy asters. 10 inches tall. Zones 4-8

How to Grow Perennial Geraniums

Most cranesbill geraniums can be started from seed, however, the newer hybrids are sterile and must be purchased as plants.

Geraniums 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 the slightly acid soil is ideal. (5.8 - 7.0)

Caring for Your Perennial Geranium Plants

Hardy geraniums require little care, once established. 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 their 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 hardy geranium live longer if divided every 3-5 years. You can divide more frequently, to keep them from spreading. But once you see the center dying out, it is definitely time to divide.

Pests and Problems of Hardy Geraniums

Slugs may attack young geranium 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.