Cranesbill (Geranium) is a hardy perennial and a true geranium. It is not to be confused with the bright red, pink and orange summer annuals that are often called geraniums but which are actually Pelargonium. There are many varieties of cranesbill, from four to 24 inches high and six to 36 inches wide. Most are around one or two feet and form a spreading clump. Hardy in zones 4-8, they are carefree garden plants, valued for their pink, blue, white and purple flowers in the spring and early summer. The foliage is also attractive and in many varieties turns brilliant shades of orange or russet in the fall.
Choose a location in full or mostly full sun. Geraniums will grow in a partly shaded area but flower best with some sun. In areas with hot summers, the geranium will require some afternoon shade.
Prepare the soil with a shovel or trowel by working in organic material to create a well-drained, moderately fertile soil. Geraniums will grow almost anywhere and actually prosper in alkaline clay soil.
Plant geraniums in the spring or fall. Allow 1 1/2 to 2 feet of space between each plant. Cover the area around the plant with a mulch and fertilize lightly.
Stake plants if necessary. Geraniums growing in wet conditions may get taller and require support.
Provide weekly waterings during periods of dryness. Keep plants "dead-leafed"--remove any leaves that have turned brown or yellow.
Pinch heavily or shear after flowering to encourage vigorous growth and new blooms throughout the summer. Garden writer Tracy DiSabato-Aust recommends cutting the the leaves of many geranium varieties, including Wargrave Pink and Johnson's Blue, down to new growth after blooming to help them keep their shape.
Deadhead (remove the finished flowers) rather than shear the geranium variety macrorrhizum--cutting back of this variety is not necessary.
Propagate the geranium by dividing in the early spring or fall, taking rooted pieces from the outside of the plant clump.
Leave the flowers on geraniums until the seeds have dropped if you wish to encourage new plants to grow from seeds. This is a good strategy when you are growing geraniums as a groundcover.
Remove any seedlings if they are not desired. Some geraniums can reseed heavily, but the seedlings are easy to lift from the soil.
Cut back the geranium in the autumn after several killing frosts.