GROWING GERANIUMS IN YOUR GARDEN

Photo by: Maya Afzaal / Shutterstock.

Zones:

Winter hardy in zones 10-11, grown as an annual or over-wintered indoors in colder zones.

Height/Spread:

Varies by type; most common varieties average 2 to 4 feet tall and wide, dwarf cultivars available in heights 5 to 8 inches, and ivy types spread 6 to 48 inches.

Exposure:

Most grow best in full sun. Regal varieties do like some partial shade and zonals will tolerate some shade. In extremely hot climates, some afternoon protection should be provided.

Bloom time:

Geraniums are appreciated for their long blooming season that starts in spring and can last into fall. If plants are kept above 45 to 50 degrees, they may also bloom in winter.

Color:

Varieties available in shades of white, red, pink, purple, mauve, orange, and reddish-black.

Other:

According to the ASPCA, geraniums are fully and totally toxic in dogs and cats. Clinical signs of ingestion or exposure are vomiting, anorexia, depression, and dermatitis. It's important to make sure your geraniums are kept far out of your pet’s reach. See more Common Poisonous Plants for Dogs and Cats.

Most geraniums belong to one of six groups, with the most common types being zonal, ivy, regal, and scented; less common are the angel and unique geraniums.

• Zonal geraniums are the colorful backbone of many summer gardens. Named for the zone of darker color on the leaf, which is very pronounced in some plants, but less visible in others. They have succulent stems with rounded, light to deep green leaves that are often variegated with darker colors and have a pungent smell. Their flowers grow in clusters and can be single, semi-double, or double. Blooms come in shades of red, purple, pink, white, orange, and rarely yellow. Most zonals will grow to 24 inches tall and wide. There are dwarf and miniature varieties 5 to 8 inches in size.
• Ivy geraniums are trailing plants that can spread up to 48 inches. They have lobed, sometimes pointed, leaves that are mid-green in color. Their clusters of single or double flowers bloom in shades of red, pink, mauve, purple or white.
• Regal or Martha Washington geraniums have rounded, sometimes lobed or partially toothed leaves that are mid-green in color. Single flowers in shades of red, pink, purple, orange, white, or reddish-black grow in clusters. Heights range from 12 to 48 inches.
• Scented-leaf geraniums release their scent when their leaves are brushed or crushed. Their mid-green leaves are sometimes variegated, and clustered flowers bloom in shades of mauve, pink, purple, or white. There are over 140 varieties in a wide range of scents, including P. capitatum (rose), P. crispum (lemon), P. denticulatum (pine), P. fragrans (apple), P. graveolens (rose), P. grossularoides (coconut), P. odoratissimum (apple) and P. tomentosum (peppermint). The lemon-scented varieties are helpful in repelling mosquitoes (see 12 Mosquito Repellant Plants). When allowed to grow in the ground, scented-leaf varieties can get quite large.
• Angel geraniums have a bushier habit and range from 9 to 36 inches in height and were originally derived from P. crispum crossed with a regal geranium. Their mid-green leaves are rounded, crinkled, and sometimes scented. They bloom in shades of pink, purple, mauve or white.
• Unique geraniums are an older group of hybrids with mid-green, rounded or lobed, sometimes incised leaves that often have a pungent scent when crushed. Flowers bloom in clusters of white, pink, red, purple, or orange. Heights range from 24 to 48 inches. For more, see A Passion for Pelargoniums.

Photo by: Tibanna79 / Shutterstock.

When to plant:

Sow seeds indoors 10 weeks before last frost. Plant seedlings outdoors in spring after all threat of frost has passed. Container-grown transplants are best planted in spring.

Where to plant:

Plant geraniums in an area that will get at least 6 hours of sun a day, in fertile, well-draining soil.

How to plant:

For potted plants, place seedlings in 4-inch containers and move up to larger pots as they grow. Plant in-ground geraniums with 6 to 24 inches between them, depending on their growth habit; don’t overcrowd them.

Pruning:

Regular pruning can help keep your geranium in shape. Pinch back new growth several times in late spring to early summer to encourage branching. Faded flowers should be deadheaded regularly to boost blooming and extend the flowering season.

Soil:

Geraniums prefer fertile, neutral to alkaline, well-drained soil.

Amendments & Fertilizer:

Apply a balanced liquid fertilizer monthly in spring and early summer. Over fertilizing can result in poor blooming, as it redirects the plant’s energy to foliage growth rather than flowering.

Watering:

Although geraniums have fairly low water requirements once established, consistent watering is best. Not enough water can cause leaf drop and wilting and too much water can cause them to get spindly. Allow the soil to dry somewhat between watering, but not completely. Water moderately during growth and sparingly in winter. Both over and under watering cause stress to the plant and may cause leaves to turn red.

Propagation:

Geraniums are easily propagated from softwood cuttings taken in spring, late summer or early autumn; best when there is a lull in blooming. Cut just above a stem node; this will encourage re-growth on the existing plant. Cut the new cutting again just below a node about 4 to 6 inches below the leafy end of the stem. Strip all but the top leaves and place in warm, damp potting soil. Water thoroughly and place in a bright location but out of direct sunlight. Seeds can be sown indoors 10 weeks before last frost. Water lightly until seedlings appear and keep them in a warm location. Seedlings can be placed outside after all threat of frost has passed.

Winter:

Your geraniums can be brought indoors for overwintering. Kevin Lee Jacobs, an award-winning food, garden and lifestyle guru who lives in New York's Hudson Valley, recommends cutting back geraniums drastically and pruning their roots before repotting and bringing indoors. See pictures of the process on his blog: How I Prepare Geraniums for Winter. Keep them in a sunny window, but don’t let them overheat.

Diseases and Pests:

Thrips, geranium budworm, spider mites, mealybugs, caterpillars, gray mold, and mildew may affect your geraniums.

Other:

Direct contact with foliage may occasionally aggravate skin allergies.