Native to South Africa, the geranium (Pelargonium spp.) Has spread far and wide due to its brightly colored flowers and utility at the backyard. Hardy at U.S. Department of Agriculture plant hardiness zones 9 through 11, geraniums prefer full sunlight and fast-draining soil. The four main kinds of geraniums all grow well in containers at any U.S. Department of Agriculture zone during warm weather.
Zonal geraniums (Pelargonium x hortorum), also known as common and garden geraniums, receive their title from the colored bands, dubbed zones, present on their leaves. Zonal geraniums contain hundreds of varieties, each creating single or double blooms in ball-shaped clusters through the growing season. Flower colors include orange, red, salmon, pink, white and lavender, and a single plant creates several balls at once. Zonal geraniums develop in a rounded, upright shape and work well in planters, borders, mixed flowerbeds and containers. A few varieties of zonal geraniums produce lacy leaves, or leaves with white margins or variegated patterns.
Martha Washington geraniums (Pelargonium domesticum) produce the largest flowers of all of the geranium types. The bi-color flowers have dark-colored centers that fade to another color, usually white. Color combinations include violet and lavender, white and pink, magenta and pink, and crimson and red. Martha Washington geraniums prefer cold weather, and their blooms appear in spring and late summer when nighttime temperatures stay consistently below 60 degrees Fahrenheit. Sometimes called Regal and Lady Washington geraniums, they have a bushlike form and develop best in pots inside.
Best-suited for hanging baskets, planters and window boxes, in which their trailing stems make the most impact, the ivy-leaf geraniums (Pelargonium peltatum) generate thick, shiny leaves reminiscent of ivy leaves. Due to their thin leaf and flowers, grouping three or more ivy-leaf geraniums is required for complete plantings. Their bloom colors include reds, pinks and purples, and the flowers appear during the summer months. Unlike the other kinds of geraniums, ivy-leaf geraniums require always moist ground and filtered shade when temperatures rise above 85 degrees Fahrenheit.
Grown mostly for their fragrant foliage, scented-leaf geraniums (Pelargonium domesticum) produce the smallest flowers of all of the geraniums. All these are heirloom geraniums, meaning that they have changed little over time. Depending upon the particular selection, the leaves might have the scent of honey, roses, chocolate, different spices, lemon and other citrus. The leaf shapes of those plants fluctuate up to their fragrance, and the leaves might be lacy, serrated, rounded or crinkly. Scented-leaf geraniums work well in containers, planters and at a backyard near a patio, porch or deck in which their eye-catching textures and striking fragrances provide delight.