We’ve heard of gardeners who consider geraniums too ubiquitous to bother with, but there are plenty of good reasons why these plants got to be so popular. Whether your passions lean toward abundant fragrance, brilliant blossoms, or spectacular foliage, you can find a geranium to suit your fancy. Generations of American gardeners have relied on these tried-and-true performers to embellish their flower beds and borders, bring charm to urns and hanging baskets, and, of course, enliven their conservatories and windowsills year-round.
More than 230 species are known by the common name “geranium,” but these enduring plants are really members of the genus Pelargonium, a group of tender perennials. The confusion started early in the 17th century, when the plants were introduced to Europe from South Africa. Botanists there first classified the plants as a species of the genus Geranium, and the plants received the nickname “African geraniums.”
That name stuck until the 18th century, when European botanists took a closer look at the flowers the species of Geranium bore: While all plants displayed five-petaled flowers, the European perennials (the “true geraniums”) had symmetrical petals, and South African plants didn’t. So in 1789, the African geraniums received a botanical makeover and were reclassified under the genus Pelargonium. (The names geranium and pelargonium derive from Greek and mean “crane” and “stork,” respectively, references to their seed pods’, or fruits’, resemblance to the birds’ beaks.)
Ever since the plants arrived here in North America in 1760, we have continued to use the common name geranium for most pelargoniums, while we call true geraniums “hardy geraniums” or “cranesbill.”
Favorite conservatory plants for more than 300 years, geraniums remain one of the most reliable flowering plants – indoors or out. Most garden geraniums fall into one of the following groups or the scented-leaf group.
* Zonal geraniums (Pelargonium X hortorum) are sometimes called “garden,” “common,” or “fancy-leaved” geraniums. Consisting of nearly 2,000 varieties, this group is the most common and widely grown. As garden plants, they’re prolific bloomers; as houseplants, they flower throughout most of the year. The one-inch flowers, in shades of red, pink, or white, can be either single, semi-double, or double and they may display pinpoints of red or pink on their petals (called bird’s-egg geraniums). Some varieties bear “notice-me” leaf markings in shades of white, silver, red, or maroon, but the leaves of all varieties are covered with just a trace of soft, fine fuzz. Colors on variegated varieties become more intense in cooler weather.
* Ivy-leaved geraniums (P. peltatum) trail up to three-foot stems of ivy-shaped, glossy leaves that cascade gracefully down from hanging baskets and window boxes. The trailing stems can also be grown as an annual ground cover. Some varieties like ‘Red Alligator’ are noted for their decorative foliage. Single and double flowers up to 1 1/2 inches span the color range of both bright and pastel palettes. “Trailing types,” as these geraniums are sometimes called, tolerate some shade better than other geraniums, making them ideal for growing outside under an eave or inside in an east- or west-facing window.
* Martha Washington (P. x domesticum) is but one name for another group, though depending on what part of the country you live in, you may call them Lady Washington, Regal, Showy, or just plain pelargoniums. The leaves are slightly crinkled, and larger than ivy-leaved geraniums, with edges that are often toothed; some even have a slight scent. Frilly 1 1/2 to 4-inch flowers have earned high visibility for this group. Although bloom time is limited to the period from early spring until midsummer, the plants are spectacular at their peak. ‘Purple Imperial’ is especially striking. Flowers are fragile and can shatter in windy areas, and Martha Washingtons also flourish in moderate temperatures, factors that make them well suited to growing indoors.
Geraniums generally require little care but do thrive under optimal conditions. Outdoors, plants should be set out in the spring after all danger of frost has passed. Once established, most plants will tolerate the occasional light frost. For best flowering, plant geraniums in a sunny, well-drained, moderately fertile soil that’s kept slightly dry. Nearly all geraniums need at least six hours of sun a day, although some shade is welcome in hot weather. In parts of the country where winters are cold, geraniums should be treated as annuals or cut back by a third in the fall and brought indoors for the cold season.
All types can be grown indoors as houseplants and thrive in pots with fast-draining potting soil. For best success indoors, place plants where they will receive at least six hours of bright indoor light and some direct sunlight. Allow the soil to dry out somewhat between waterings, and keep the humidity low (don’t mist the leaves). Pinch back young plants occasionally to encourage bushiness and remove faded flowers to keep blooms coming even longer. During winter, plants should stay cool (55 [degrees] to 65 [degrees] F is best) and the soil kept slightly dry. Grow zonal geraniums in a sunny window that stays above 50 [degrees] F at night and you’ll be rewarded with colorful blooms throughout most of the year.
Scented-leaf geraniums (Pelargonium grayedlens, P. tomentosum, and others) evoke aromatic pleasures as well as optical ones. Some varieties tantalize with blends of rose and lemon; others tease with hints of sweet ginger, spicy nutmeg, or fruity apple. And if these aromas aren’t enticing enough, the wide range of leaf shapes – from widely lobed and velvety to lacy and fernlike – are a decorator’s dream.
Touching a scented geranium provides an unforgettable experience, for when the leaves are bruised even slightly, minute beads of fragrance erupt into the air. The essential oils are often used in aromatherapy products and cosmetics while crushed leaves are a potpourri staple.
There are more than 100 varieties of scented geraniums in common cultivation. Some display showy flowers, such as the eucalyptus-scented ‘Clorinda’: Its richly colored orange blooms (the largest of all scented geraniums) are as striking as its scent. Others have tiny flowers; ‘Lady Plymouth’ has dainty, soft pink flowers along with its wonderful rose and citrus scents.
Often the common name is symbolic of its character. ‘Oak Leaf’ refers to its leaf shape while ‘Apple Scented’, ‘Lemon Scented’, and ‘Nutmeg Scented’ describe the scent. But, alas, chocolate lovers may feel somewhat cheated by ‘Chocolate Mint’, which refers only to the unusually striking dark-green foliage with chocolate-colored centers.