Two types of plants are commonly referred to as geraniums. One, which is the true geranium, is really the cranesbill, a bushy long-lived perennial plant. The other is the red, pink or white-flowered plant seen everywhere in flower boxes and pots which is correctly called Pelargonium.
There are five types of pelargonium: zonal, dwarf and miniature zonal, regal, ivy-leaved, and scented-leaved.
Zonal pelargoniums have rounded leaves, usually marked with a distinct dark zone and single, semi-double or double flowers. Some cultivars do not have a zone and others have golden, white-variegated or tri-colored leaves.
Dwarf and miniature zonal pelargoniums are 5-8 inches tall, bushy and free-flowering. They come in a wide range of colors and have green to greenish-black leaves.
Regal pelargoniums, also called Martha Washington pelargoniums, are small shrubby plants with rounded, deeply cut leaves and wide, trumpet-shaped flowers, often in exotic colors.
Trailing or ivy-leaved pelargoniums have rounded, lobed, ivy-like leaves and flowers similar to the zonals. They are used mainly in hanging baskets or are planted so that they spill over the edge of a raised bed or wall.
Scented-leaved pelargoniums have small, delicate flowers with five leaves and fragrant foliage which may smell like lemon, pine, nutmeg, rose, lime, apple, apricot, chocolate or peppermint.
All types of pelargonium grow best in full sun with well-drained soil. They should left to dry out between waterings. Cut back to encourage branching if they grow too tall and produce flowers only at the top.
Now, the answer to the question I have been asked more than any other since I became a Master Gardener: How do you overwinter geraniums (pelargoniums)?
Pelargoniums should be brought indoors when nighttime temperatures get down to 40 degrees. If there isn’t space to treat your pelargoniums as houseplants over winter, remove the plants from their pots and shake the soil from the roots. Cut off flower heads and place the plants in brown paper bags or cardboard boxes, closing the tops so light doesn’t reach them. Store the bags or boxes in a cool, dark area of the basement. The plants will go dormant and the leaves will turn brown and fall off, but about mid-February they will start to grow new yellowish leaves. At that time, plant them in the pots in which they will spend the summer, or in a temporary container, until all danger of frost is past in spring when they can once again be moved outdoors.
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