The common garden or zonal geranium is one of the most popular outdoor flowering plants. Not a true geranium, it actually belongs to the genus Pelargonium. There are more than 200 Pelargonium species, most native to South Africa. In addition to garden geraniums, the scented-leaf geraniums, ivy geraniums, and the Lady or Martha Washington geraniums are the four major groups of cultivated "geraniums."
The Lady or Martha Washington geraniums (Pelargonium x domesticum) were very popular in the United States in the early 1900's. The common name is derived from a popular variety introduced by that name. Large, brightly colored flowers are their outstanding ornamental feature. Flower colors include white, pink, red, purple, and yellow; the upper petals often having darker blotches or veins. Many have ruffled petals. They are also known as regal geraniums.
Despite their eye-catching flowers, Lady or Martha Washington geraniums are not widely grown. These geraniums require cool (50 to 60 F) night temperatures in order to bloom. Because of this requirement, Lady or Martha Washington geraniums often fail to bloom when grown outdoors.
In Iowa, Martha Washington geraniums are best enjoyed as indoor flowering plants. Flowering plants, often available at flower shops and greenhouses in late winter and early spring, should bloom for several weeks indoors. After flowering, discard the plant.
This article originally appeared in the July 13, 2001 issue, p. 88.