Geraniums comprise more than 200 species in the Pelargonium genus. They are some of the most common flowering plants used in home landscaping. With their attractive, light green, scalloped leaves and flowers of all hues that bloom in clusters, geraniums are hardy and carefree. They do well as potted plants and are among those you'll also enjoy in your flowerbeds. The scented varieties add delightful fragrances to your garden as well as unusual flowers and leaf forms.
History and Description
Most species of geranium come from their native South Africa. They are perennial plants with a thick, knobby root, gray-green stems covered with fine hairs and mostly rounded leaves with scalloping around the edges. Flowers come in all colors and are borne on stems that rise above the plant several inches. Most geraniums are frost sensitive and in many climate zones, gardeners use them as an annual, replanting new plants every spring.
Common Garden Geraniums
Pelargonium hortorum is the botanical name of the most common geranium grown in home gardens. This variety does well outdoors in USDA climate zones 9, 10 and above (Houston to Honolulu), and is popular in areas such as Phoenix, Arizona, because it is frost hardy in that zone. It's a shrubby perennial that grows to 3 feet high. Its clusters of flowers are 2 inches wide---they range from white to red and are also bicolored and multicolored. In hot climates, this geranium needs some protection from summer sun.
Martha or Lady Washington geraniums (Pelargonium domesticum) are a popular species because of their brightly colored flowers that burst into yellow to dark purple blooms all summer long. This species needs colder summer nights in order to bloom well, so it is suited to more northern climate zones. The hardy geranium includes numerous species and is popular as a low-maintenance plant. The variety Splish Splash is white with streaks of lavender. Others include Johnson's Blue, which sports blue, cup-shaped flowers.
Whatever variety of geranium you choose for your garden, the care is the same. Geraniums favor sandy soil amended with compost or other organic material. Plant them in spring after your final frost in an area that receives full sun. There's no need to give them much fertilizer---in fact, they do better without it. Just dig in 2 lbs. of a balanced fertilizer having an N-P-K ratio of 10-10-10 for every 100 square feet of planting area before you plant and then water it into the soil. Allow your plants to dry out a bit between waterings, but don't allow them to droop from too little moisture.
The scented leaf geraniums are among the most fragrant of flowering plants. Ranging in scent from lemon to peppermint, pineapple, rose and nutmeg, the scented geraniums typically have a leaf structure that appears more lacy and narrow than the common garden geraniums.