General: Geraniums are popular flowering plants for indoor and outdoor use. There is great variation in leaf, flower and growth characteristics of geraniums. They may vary in height from six inches to several feet, depending on the cultivar selected and the care given the plants. Many forms and species are available. Some of the types of geraniums for home and garden use, and their most distinct characteristics, include:
Common Garden Geraniums – usually characterized by distinct leaf markings. They include selections with tri-colored leaves, silver leaves, leaves with white markings, and fancy-leafed geraniums. Flower colors are usually pink, red and/or white.
Ivy-leaved Geraniums – are trailing in habit and have leaves that resemble ivy leaves. They are commonly used in hanging baskets and window boxes.
Scented-leaved Geraniums – are prized for foliage aromas. Scents include lemon, rose, peppermint, nutmeg and others. Many have deeply lobed leaves.
Light and Temperature: Geraniums do best in full sunlight indoors. They can be grown indoors for their ornamental value, as well as for maintaining plants over the winter for outdoor plantings. They should be placed where temperatures average 65 to 90° during the day, and around 55° at night. Avoid locating them in cold or drafty areas.
Fertilize: Fertilize monthly from March through October and Bi-monthly the rest of the year. Use one teaspoon of 20-20-20 fertilizer, or two teaspoons of a 10-10-10 fertilizer per gallon of water. If light intensity or temperature is low, reduce the fertilizer accordingly.
Soil: Grow geraniums in a soil medium that is high in organic material. A good soil mix consists of equal parts garden loam, peat moss and coarse sand or perlite. Other mixes can work equally well. Commercial soil mixes are very good.
Water: Allow the soil to become moderately dry between waterings, and make sure there are one or more bottom holes in each container. Good drainage is essential.
Location: Geraniums should not be planted outdoors until the danger of frost is past. They do best in a location with six to eight hours of sunlight per day. When planted in areas of moderate shade, flowering is reduced. Geranium plants tend to break and wilt in windy locations so, if possible, protect the plants from strong wind.
Soil: The soil should be well drained with adequate organic matter. Fertilize new flower beds with one pound of a 10-20-10 fertilizer, 2 pounds 6-10-4, or comparable amounts of similar fertilizer per 100 square feet. Incorporate the fertilizer into the soil. If fertilizer is applied after planting, make sure the soil is moist.
Water: Water geraniums when the soil becomes moderately dry. Never allow the plants to wilt or the leaves will turn yellow and drop off. Give the soil a good soaking at each watering, and avoid frequent light waterings. Keep water off the foliage because moist foliage favors the development of disease. Mulching usually is desirable for most summer flowers, including geraniums.
Grooming: Removing dried or faded flowers from the geranium plants promotes more blooming, and makes the plants more attractive. Pinch tall plants occasionally to encourage well branched, stocky plants.
Overwintering: Geranium plants can be overwintered in several ways. Before frost, whole plants can be taken from the garden, tied in bundles, and hung by root ends in a cool basement or moist area for the winter. Storage temperature should be between 35 and 45°, and the humidity should be 80 percent or higher. The plants can be cut back to about 1/3 of their height and planted outdoors in May, or potted indoors in late winter.
Plants also can be dug in the fall, taking as much of the root system as possible. Place the plant in a pot large enough to accommodate the root system, cut back to 6 inches in height, place in a sunny window and water and fertilize as needed. Geraniums also can be overwintered from cuttings taken in late summer or early fall.