Pelargonium x domesticum

Lady Washington Pelargonium, Matha Washington Pelargonium
Geraniaceae
Annuals, Perennials

PELARGONIUM

The common name “geranium” is widely used for Pelargonium—but botanically speaking, it is not really accurate. To the botanist, pelargoniums are woody-based perennials (most of them native to South Africa) that endure light frosts but not hard freezes, and have slightly asymmetrical flowers in clusters. True geraniums, on the other hand, are annuals and perennials native mainly to the Northern Hemisphere, bearing symmetrical flowers either singly or in clusters.

In the past, the commonly grown pelargoniums were Pelargonium x domesticum, Lady Washington pelargonium; Pelargoniuim x hortorum, common geranium (this group also includes variegated forms usually referred to as fancy-leafed or color-leafed geraniums); and Pelargonium peltatum, ivy geranium. Today, other kinds are increasingly available, including many with scented leaves.

Plants perform best in areas with warm, dry days and cool nights. They can be grown outdoors year-round where winters are very mild; in these areas, they bloom throughout warm weather. Elsewhere, they are summer annuals or houseplants. In cold-winter climates, move plants indoors before the first frost or take cuttings for next year.

Plant in any good, fast-draining soil. Amend poor alkaline soil with plenty of organic matter. Geraniums growing in good garden soil need little fertilizer; those in light sandy soil should receive two or three feedings during active growth. Remove faded flowers regularly to encourage new bloom. Pinch growing tips of young, small plants to force side branches. All geraniums do well in pots; they bloom best when somewhat potbound. Common pests include aphids, whiteflies, and spider mites. Geranium (tobacco) budworm may be a problem in some areas; affected flowers look tattered or fail to open at all. Prevent or limit infestation by spraying plants with Bacillus thuringiensis (Bt).

Pelargonium x domesticum

This hybrid perennial is grown everywhere as an annual. Erect or somewhat spreading, to 3 ft. tall and wide. Heart-shaped to kidney-shaped leaves are dark green, 2 to 4 in. wide, with crinkled margins and unequal sharp teeth. Loose, rounded clusters of large (2-in. or wider), showy flowers; colors include white and many shades of pink, red, lavender, purple, with brilliant blotches and markings of darker colors. Can be planted in beds but tends to get rangy. First class potted plant. Some varieties are used in hanging baskets.