Colorful geraniums (Pelargonium spp.) spice up flower beds, window boxes, containers and hanging baskets throughout U.S. Department of Agriculture plant hardiness zones 3 to 11. With 280 known species and hundreds of varieties in shades of red, pink, white and orange, geraniums thrive in containers and flower gardens. In USDA zones 10 and 11, plants can live outdoors all year. Many geranium species feature scented leaves and small, variously shaped flowers. Choosing plants for decorating, gift-giving, craft-making or landscaping depends on the colors and varieties you prefer.
Common geraniums (Pelargonium x hortorum), also called zonal geraniums, are available in most garden stores and are suitable for containers, hanging baskets, window boxes or planting directly into the ground. Varieties have bands – zones -- of darker leaf pigments, multicolored leaves or green foliage edged in silver or white. Common geranium flowers consist of single or double floret clusters, about 3 to 6 inches wide. You can mix shades of pinks, reds, whites and corals to create colorful flower beds or planters.
Suitable for window boxes, bookshelf containers and hanging planters, ivy-leaved geraniums (Pelargonium peltatum) are vine-like plants with shiny, leathery leaves and small-petal flower clusters. The plant grows up to 3 feet long. Ivy-leaved geraniums in shades of lilac, pink and red prefer northern light exposure, morning sun and afternoon shade when the thermometer reaches 85 degrees Fahrenheit. Ivy-leaved geraniums thrive in well-draining potting media that stays moist but not overly wet.
Some geranium varieties do not have bright flowers but instead feature spicy, herbal, aromatic leaves that are used for making teas, sachets, potpourri, preserves, punches and sweets, notes Clemson University Extension. For example, rose geranium (Pelargonium graveolens), sprouts deep green, hairy leaves that smell like roses. Lemon geranium (Pelargonium crispum) can grow up to 2 feet tall. Plants have small pink flowers and curly leaves that emit a lemon-like fragrance. Both varieties are grown outdoors in USDA zones 10 and 11. Other Pelargonium geranium varieties smell like peppermint, nutmeg, cinnamon, orange and apple and are sometimes used as cooking herbs.
Perennial “Martha Washington” geraniums (Pelargonium domesticum) -- also called “Lady Washington” or “Regal” -- feature bright, hot colors in reds, yellows, pinks, purples and corals. Although grown outdoors year-round in USDA zones 10 and 11 and as annuals in zones 3 to 10, “Martha Washingtons” are better suited as indoor plants. They do not tolerate extreme hot or cold weather and must have nighttime temperatures of 50 to 60 degrees F to bloom, advises University of Minnesota Extension. Florists and garden stores often feature “Martha Washingtons” as indoor flowering container plants.
Whether planting in outdoor containers or directly into flower beds, soil temperature should be about 60 degrees Fahrenheit. Do not plant geraniums and other flowers until after the danger of frost as passed. Geraniums prefer direct sun -- about eight hours daily -- to bring steady flowering. Geraniums grow well in soil with pH of 6.5; you can add lime if the number is below 5.5. Adding organic matter such as leaf mold, ground bark, perlite or peat moss to well-draining soil provides nutrients to plant roots. Fertilizing with a 5-10-15 or 6-12-12 NPK chemical mix helps plants grow, but overfeeding them may stunt flower growth. Water garden geraniums as needed but do not let roots sit in puddles. Removing faded flowers and dead leaves helps protect geranium plants from fungal diseases.
- University of Florida IFAS Extension: Pelargonium x Hortorum Geranium
- Clemson Cooperative Extension: Geranium
- University of Georgia Extension: Geraniums
- North Carolina State University: Geranium Culture for Home Gardeners
- University of Rhode Island Extension: Geranium Culture
- Zip Code Zoo: Pelargonium Graveolens
- Fine Gardening: Pelargonium Crispum “Variegatum”
- Missouri Botanical Garden: Pelargonium x Domesticum
- University of Minnesota Extension: Outdoor-Indoor Geranium Culture
- Photo Credit Creatas Images/Creatas/Getty Images
- University of Massachusetts Amherst: Greenhouse Management: Growing Quality Geraniums
- USDA Natural Resources Conservation Service: Plants Profile: Geranium
- Zip Code Zoo: Geranium
- University of Kentucky Extension: Geraniums for Kentucky Gardens
- Iowa State University Extension: Geranium Care
- North Carolina State University: Fertility Management for Geraniums
- Royal Horticultural Society: Pelargonium (Geranium)