Pelargoniums, commonly known as common geraniums, are summer-flowering plants that come in a variety of colors. They are popular for adorning hanging baskets, pots, and garden beds. These tender annuals are both drought and heat tolerant and can bloom continuously from June until the fall frost. To learn more about cultivating and caring for pelargoniums, refer to the following guide.
It’s important to note that although they’re commonly referred to as “geraniums,” pelargoniums are not true geraniums, which belong to a different genus (Geranium) and are cold-hardy perennials. This guide pertains specifically to growing the tender annuals that are known and loved as common geraniums (genus Pelargonium).
Planting Geraniums
Commonly known as geraniums, Pelargoniums thrive in full sunlight and need at least five hours of direct sunlight per day. They are not as demanding in terms of watering as some other annuals, but they do appreciate moist and well-drained soil.
These plants are often grown in pots or as container plants, and they can be kept outdoors in a location that receives partial to full sun until the fall frost dates. However, they cannot survive several frosts or the first hard freeze, as they are annuals and will die off.
When to Plant Pelargonium
As sun-lovers, pelargonium should not be put outside until nighttime temperatures are regularly above 55°F (13°C). Then, in late summer, when nighttime temperatures start to dip under this temperature, bring them inside.
How to Plant Pelargonium
When purchasing geraniums from a garden store, it’s essential to carefully observe their color and size. Healthy plants will have leaves with no discoloration either on or beneath them, and their stems will be sturdy rather than straggly. It’s also crucial to avoid any plants with signs of pests.
To prevent root rot, place the plants in large pots with drainage holes. For ample root spread, it’s recommended to plant a single plant or possibly two plants in a large pot that is at least 20 gallons and 18 to 24 inches wide. It’s important to use a well-draining potting mixture rather than heavy soil when planting in containers since geraniums don’t like to be in soggy or compacted soil.
When planting in the ground, it’s best to avoid overcrowding to allow for adequate air circulation. Providing sufficient space for the roots of any geranium variety is critical as they will deteriorate without room to grow. Additionally, to prevent pests, practice crop rotation and avoid planting pelargonium in the same spot every year.
How to Care for Geraniums
1. If you’re planting in the ground, add a light mulch to cover the soil to cool the root zone.
2. Allow soil to dry to some extent between waterings, then water thoroughly. Over-moist soil does more damage than under-watering. Do the finger poke; if it’s dry at 1 inch depth, then water. Do not water from overhead nor splash the foliage when watering or you’ll invite disease.
3. Deadheading is important for continuous bloom throughout the summer. Deadhead all spent blooms. Also deadhead after heavy bloom or a strong rain. One reader shared a tip, “For continued reblooming, finger pinch just below the spent flower as much as possible. I did and each of my pelargoniums bloomed from spring into fall year after year.
4. To promote bushiness and curtail legginess, pinch back the stems.
5. During active growing months, fertilize every 2 weeks or so. Use a water-soluble fertilizer at half-strength. Don’t fertilize in winter, when the plant should be dormant.
6. If you’re bringing in the plant for winter, water much less, but do not let the roots dry out entirely. Geraniums do best when given a period of dormancy through the winter months, during which they use less water and do not grow much. See below for more overwintering instructions.
7. Geraniums can be repotted in spring to encourage new growth—or, if they look like they need to be refreshed.
Overwintering Geraniums
1. Geraniums that have spent the summer outdoors can be kept as houseplants, provided they get lots of sun. In northern climes, the sun may not be strong enough in late winter to stimulate buds on some varieties.
2. Before the first fall frost, lift the plants and, using a sharp, clean knife, cut the stems back in a shapely fashion to about 6 to 8 inches. They should not have to support great masses of leaves in the low-sunlight environment they are about to enter. Save a few stems as cuttings to root—an easy way to multiply your plants.
3. Transplant the “mother plant” to the smallest pot possible—enough to just fit the roots—using regular potting soil to fill.
4. Keep the plants in the shade for a week, then place them in a sunny spot (they need all the sun they can get) and keep them cool.
5. During winter, geraniums grow best with night temperatures of 50° to 60°F (10° to 16°C) but will survive if they drop to 32°F (0°C) and/or rise above 80°F (27°C), as long as they are kept relatively dry.
6. When new growth appears in the spring, cut off all the old leaves.
Keeping the new growth is often more challenging than getting it to appear. Here are some tips to help you with that:
It is essential to water the plants only when the leaves show signs of drooping, and it is best to provide only small amounts of water. It’s crucial not to fertilize or feed the plants as they need rest.
If you wish to have your geraniums blooming for Memorial Day after overwintering, it’s recommended to pinch them back in February. When the warm weather returns and there’s no risk of frost, transplant the plants to beds or pots, according to your preference.
