The Pelargonium species most often go by the common name annual geraniums or zonal geraniums. These tropical perennials from South Africa are usually grown as annuals, though it is possible to overwinter them in very warm climates. Regal geraniums are favorites for container plantings and hanging baskets, and they also work well as bedding plants. Plant them in full sun after the danger of frost has passed for springtime blooms. In climates with cold winters, bedding plants should be pulled up and discarded as soon as frost kills them. Container plants can be brought indoors if you wish. You can grow them as houseplants in a window with bright, direct light. Or, you can overwinter your geraniums in their dormant state—a common strategy for geraniums grown in hanging baskets. Some people take cuttings at the end of the growing season, rooting them indoors, then planting them in potting soil several weeks before outdoor planting time arrives again.
Light
These plants will grow in full sun or partial shade, but they bloom best in full sun punctuated with some shady relief in the hottest hours of the afternoon. Plants that stop blooming in the summer heat may just need a little shade for the hottest time of the day.
Soil
Regal geraniums prefer rich but well-drained soil that is slightly acidic—5.8 to 6.5. When growing in containers, use a well-draining general-purpose potting soil—not garden soil.
Water
Stressing the plants slightly by watering only after the soil has been sitting completely dry for a day or two seems to encourage more profuse blooming. These are relatively drought-tolerant plants, which is why they are so popular for cemetery urns that are tended to only sporadically. However, do not leave them dry for so long that they start dropping leaves and declining.
Temperature and Humidity
These are warm-region plants that dislike cold temperatures. They thrive at the same temperatures preferred by humans—55 to 80 degrees Fahrenheit. Prolonged temperatures below 55 degrees Fahrenheit will stunt these plants, and temperatures at the freezing point usually kill them. It may be possible to overwinter regal geraniums as far north as zone 7 if you cover them heavily in the winter, but it is generally best to grow them as annuals.
Fertilizer
Regal geraniums are not heavy feeders, but since they are usually grown in containers, a light feeding with your favorite fertilizer, every two to four weeks, will keep them vigorous.
Regal Geranium Varieties
Although there are more than 200 Pelargonium species, only a few are used as the common annual geraniums for ornamental gardening:
Pelargonium x hortum: This is the most common form, the zonal geranium that is so often planted in patio pots and cemetery plantings, and also as a garden bedding plant. Flowers are generally solid tones of red, purple, pink, salmon, magenta, white, or bicolors. The leaves are oval, growing on succulent stems. Flowers can be single with five petals, or double. The common name “zonal geraniums” derives from the area of red, blue, or purple color that stripes through the middle of the leaves. These color zones are more visible in some cultivars and nearly invisible in others. Pelargonium paltatum: This is ivy-leaved geranium, which looks very similar to zonal geraniums but with a trailing habit that works well in hanging baskets and window boxes. Flowers are usually solid tones of pink, red, lilac, or white. Pelargonium × domesticum: These are larger plants with large, crinkled leaves. Plants are upright with woody stems, growing to 3 feet or more. These plants are derived from a hybrid of P. grandiflorum and P. cucullatum, and the flowers often have a distinctive speckled look that is different from the more solid colors of other annual geraniums. A miniature version of this type is known as the angel geranium. Pelargonium domesticum: Scent-leaved geraniums get their fragrance from the oil in their leaves. They can mimic all kinds of scents, including lemon, rose, mint, pine, fruits, and even chocolate. The flowers tend to be small and often insignificant, and the leaf shapes will vary. Besides their ornamental and fragrant appeal, many can also be used in cooking.
Regal Geranium Cultivars
Every year, it seems that there are more Pelargonium hybrids to choose from. There are regal geraniums that are tulip-flowered, cactus-flowered, and some with spiky star-shaped flowers. There are also the fancy-leaved varieties, grown more for their variegated and patterned foliage.
‘Appleblossom Rosebud’: Pom-pom flowers in a pink and white bicolor’Black Velvet Rose’: Dark, chocolate-brown leaves with only a narrow band of green and bright rose-pink flowers’Calliope Dark Red’: A cross between zonal and ivy-leaved, with double, dark-red flowers’Divas Orange Ice’: An F1 hybrid with bi-colored white and soft orange flowers that look like creamsicles
Propagating Regal Geraniums
You can start regal geraniums from seed, cuttings, or transplants. Taking cuttings is a traditional method of propagating geraniums and maintaining favorite varieties. If you choose to take cuttings, make sure you only use healthy, vigorous plants.
How to Grow Regal Geranium From Seed
Most geraniums are F1 hybrids that will not come true from seeds taken from the plants. If you choose to grow commercial seeds, be aware that these slow-growing plants can take as long as 16 weeks from planting to flowering. For an early May planting date, for example, you’ll need to start seeds in January.
Potting and Repotting Regal Geranium
Regal geraniums are a very popular plant for patio containers, hanging baskets, and window boxes. Make sure the container has plenty of drainage holes. Regal geraniums actually bloom a little better when slightly root-bound, so a smallish pot is fine for these plants. When grown in containers, the plants need to be fed more often than when grown as bedding plants.
Overwintering
Overwintering regal geraniums is a viable option for these versatile plants. If they are in containers, keep them indoors as houseplants to brighten up your windows in the winter. They’ll thrive in bright light with regular watering until they can go back outdoors in the spring. Or, you can store the plants while they’re in their dormant state by following these steps:
Common Pests & Diseases
Regal geraniums can also be susceptible to whiteflies and aphids. Insecticidal soap, then a water rinse applied after the soap has dried, is an effective treatment for these pests. Webs or parched leaves are signs of spider mites. Treat for these as soon as possible. Isolate affected plants from any others, and apply a 1 percent solution of neem oil spray, soaking the plant and the soil. Regal geraniums can be problematic to grow in very warm, humid climates where they can be very susceptible to leaf spots and gray mold. These fungal problems can be combatted by pruning the plant to improve air circulation or using copper-soap fungicides. Make sure to water slowly at the soil level and avoid splashing soil onto the leaves.
