The odds are that the lush, potted Geraniums brightening your patio are not True Geraniums (Geranium sp.); the nursery plants sold as Geraniums are actually of the genus Pelargonium. While True Geraniums are frost-hardy perennials generally planted in flower beds, Pelargoniums are often container plants and, although also perennials, require more care in cold temperatures. Easy-going, versatile plants, they add a splash of vibrant color throughout the summer season in pots, hanging baskets, and window boxes in Mediterranean climates.
Growing Conditions and General Care
Work organic compost into high-quality container potting soil that contains ingredients such as peat moss, vermiculite, and perlite. Use this compost/soil mixture to fill pots for your Pelargoniums. Good drainage is essential to Pelargoniums, so choose containers with adequate drainage holes. If your Pelargoniums are already in pots, spread organic compost lightly on the soil surface and work in, taking care not to dig up the plant's roots.
Choose locations getting direct sun for most Pelargoniums. They need at least six hours of sun daily. Martha Washington and Regal types prefer a site that is shady in the afternoon. All Pelargoniums need afternoon shade if your area regularly sees summer temperatures exceeding 90 degrees Fahrenheit (32 degrees Celsius).
Feed your Pelargoniums every two weeks with a balanced fertilizer like 10-10-10 or 20-20-20. Buy fertilizer that dissolves in water for easier application. Every third watering, add Epsom salts — magnesium sulfate — to the plant water — 1 teaspoon per 1 gallon — to provide magnesium. Or, add a slow-release fertilizer to the soil mix when you plant the geraniums in the pot — it feeds them all season.
Water your potted Pelargoniums until the excess runs out the drainage holes, then allow the potting soil to dry before watering again. In hot summer temperatures, poke a finger 2 inches (5 cm) into the soil in the container every day and get out the watering can if the soil is dry—water plants in the morning instead of the evening to reduce disease.
Snip off the faded flowers of potted Pelargoniums. Deadheading your plants helps them produce new flowers more rapidly. At the same time, trim stems by one-third to encourage branching. Pinch off dead and discolored leaves.
Cut back your Pelargoniums by about two-thirds if and when the weather drops below 45°F (7°C). Move the pots indoors to a sunny, south-facing window that gets at least four hours a day of direct sun. Stop fertilizing and limit water to once a week, keeping the plants on the dry side, while they are in the house. Begin to add fertilizer to the plant water again when you see new growth in late winter or early spring. As spring arrives, move your potted Pelargoniums outside gradually, adding a little more time each day to allow them to acclimate to cooler air.
True Pelargoniums are cold-hardy and drought tolerant. Different cultivars do well in sun or shade. Most need afternoon shade in hot climates.
Put Pelargonium containers in a cemented-over backyard area, if you have one. The flowers mask the cement and flourish from the extra warmth of the reflected sun.
Make your backyard garden different each year by rearranging your container plants in new and exotic ways. Try new plant combinations and change to larger containers. Experiment with Ivy Geraniums (Pelargonium peltatum). This fast-growing, trailing geranium grows year-round in Mediterranean climates.
Try Scented Geraniums for their lovely smells, including rose, lemon, and mint. Pick and dry their fragrant leaves as a welcome addition to potpourri.