There are over 300 species in the Geranium genus, both annuals and perennials, upright growers and trailers. Commonly called cranesbill, geraniums are often confused with Pelargonium, which is a separate genus. Geraniums readily self-seed yet are sometimes stubborn germinators when cultivated.
Meadow cranesbill (Geranium pratense) is a perennial plant that blooms in lovely blue flowers. Growing to heights of 24 to 36 inches, meadow cranesbill should be grown in full sun in cooler areas of the U.S. but give it some afternoon shade in the warmer regions. Plant meadow cranesbill seeds after the last frost date in your area. It is a bit slow to germinate, sometimes up to 3 months or more, so don’t give up on it too soon. Meadow cranesbill is hardy to United States Department of Agriculture (USDA) Hardiness Zones 4 a to 9b.
Geranium maculatum, or spotted cranesbill, is the only commonly grown geranium that is native to the U.S. Pink to lavender flowers bloom from March through July on a plant that grows from 1 to 3 feet. If you have a shade garden you will particularly like the spotted cranesbill for its ability to thrive in shady areas. Collect the seed pod from the plant when it begins to turn dark, generally 3 to 4 weeks after it blooms. Place it in a paper bag and allow it to remain there until it pops and releases the seeds. If you won’t be planting immediately, store the seeds in a dry area in the refrigerator. Plant outdoors in late fall or in early spring. There is no cold treatment required.
Wargrave pink (Geranium x oxonianum) is a hardy variety of hybrid geranium. It blooms almost the entire summer in a delicate shade of pink flowers. Wargrave pink is more drought-tolerant than many other geranium cultivars and takes well to either full sun or partial shade. This is not a good variety for the deep South as it is intolerant of humidity. Wargrave pink is the compact, mounding type of geranium that looks striking in cottage gardens or as a ground cover for small, shady spaces. Wargrave pink seeds are available from a variety of online retailers and should be planted after the last frost date.