No garden is complete without colorful geraniums (Pelargonium), and they’re so easy to grow that practically any gardener can be successful. Native to South Africa, geraniums can be grown in garden beds in USDA zones 8 through 11 where winters are mild. But, they bloom even better when they are slightly root-bound (tightly packed, such as in a container), if the container soil has good drainage.
When grown in pots, you can relocate your geraniums at a moment’s notice, whether to show them off near an entry, to bring them indoors during surprise freezes, or to move them to a shadier spot during the hottest days of summer.
Types of Geraniums
These popular perennials are available in a multitude of species and hybrids, each with its own benefits. Some, like zonal geraniums (Pelargonium x hortorum), a cousin to perennial geraniums, are grown for their variety of colorful, sturdy flowers and velvety rounded leaves. They get their name from the zone of red, blue, or purple colored striping through the middle of their leaves,
Others, such as the handful of species known as scented geraniums, are beloved for the many different fragrances of their finely-cut leaves. Although the plant is not edible, the fragrant leaves of rose, mint, chocolate, and lemon scented geraniums can be used to impart delicate flavors to sugars, preserves, and drinks.
Whatever species or hybrid you grow, geraniums need protection from winter freezes, summer heat, and soggy soil. If you follow a few simple tips, geraniums can be one of the easiest and most prolific flowers you’ll ever grow.
Provide Full Sun
Geraniums require between six to eight hours of full sun each day to bloom well, so allow them to soak up those rays by placing the container on the south side of walls, on patio tabletops, or as an accent in sunny areas of the garden. If you notice that your plant has stopped blooming in summer, don’t panic. Geraniums have a tendency to stop flowering during especially hot weather, so just move your container somewhere where it will receive some afternoon shade if you live in a hot climate.
Mind the Moisture
Although geraniums do require moisture, they will likely rot if their potting mix stays wet for too long. To prevent this, water only when the top inch of the soil is dry, and make sure that moisture can easily drain through drainage holes in the bottom of the pot. Geraniums are relatively drought-tolerant plants—they can survive a fair amount of neglect but should be never be allowed to dry out completely.
Keep Geraniums Blooming
To keep your geraniums in bloom, deadhead faded flowers by removing the entire flower stalk down to where it meets the main stem.
To keep plants bushy, full, and packed with flowers, use a sharp pair of scissors, or even your fingers, to snip or pinch about a 1/2 inch of growth from the end of each stem. Doing so causes the plant to grow two new stems and creates a fuller look and the potential for more blooms.
Geraniums bloom best when they're somewhat root-bound, so repot your geraniums into a larger container only when necessary, and use a container only one size bigger than the previous one.
Geraniums are heavy feeders, so fertilize your plants every few weeks during the spring and summer with a balanced fertilizer according to the product label. Stop feeding at the end of summer.
Protect From Cold Weather
Gardeners in USDA hardiness zones 8 to 11 can cover up and protect their geraniums on frosty nights, but gardeners in colder zones should overwinter them indoors. Bring your geraniums indoors before the first hard frost and place them in a sunny window, or let them go dormant in a cool, dark place.
Keep Them Healthy Indoors
Keeping geraniums in bloom indoors can add some cheer to the drab winter months. The key is to keeping them healthy is maintaining temperatures above 50 degrees Fahrenheit, providing six to eight hours of sun per day, allowing the top inch or two of soil to dry out before watering, and keeping an eye out for any diseases or pests.
Watch Out For Spider Mites
Keep an eye on your overwintering geraniums for signs of a spider mite infestation. You might notice parched leaves, webbing, or tiny specks that resemble spiders when viewed with a magnifying glass. Spider mites are best treated early, so move quickly as soon as you spot the problem. First, separate the affected geraniums from the rest of your plants and then treat them consistently and aggressively with neem oil. While it won't kill them immediately (it's not a poison), it will interfere with their biological systems, slowly ending the infestation. Soak both the plant and the top inch of the soil for best results.
Let Your Plants Go Dormant
If you’re lacking space indoors or don’t have a sunny window, you can let your geraniums go dormant for the winter by placing them in a cool (below 70 degrees Fahrenheit) and dark space, such as a garage or basement, if the temperatures don't dip below freezing. Let the soil dry out so that it remains only barely moist. Remove the leaves and flowers as they die off, and inspect the roots and crown occasionally for rotting parts, removing any rot with a sharp, sterilized knife.
After the last frost in spring, resume your normal watering schedule and begin placing your geranium container outdoors each day. You will want to harden off your plants for about a week, slowly moving them to locations with more sun so that the leaves can adapt to the extra sun without burning. After your plant is in position and the weather is warm enough for the plant (nighttime temps above 50 degrees Fahrenheit), begin feeding.