Scented Geranium

Pelargonium

Scented geraniums were known originally as rose or lemon geraniums.  They were extremely popular in Europe and North America throughout the 18th and 19th centuries, but lost favor early in the twentieth century with all the previously unfamiliar plants being introduced. Now, however, they are coming back into popularity.

Scented Geranium, Dr. Livingston Pelargonium radens A large form of Pelargonium radens, 'Dr. Livingston' has rough, bristly leaves that are finely cut--very ferny. The plant produces lovely rose-colored flowers and the leaves emit a lemony-rose fragrance. Also called 'Skeleton Rose.'  Tender perennial. Over winters outdoors in zones 8-10; should be potted and brought indoors in mid-autumn in colder climates.

An extremely large genus, Pelargonium encompasses garden and pot geraniums as well as the several hundred varieties of scented geraniums. Their aromatic foliage which gives scented geraniums their name, is used as stewing herbs, potpourris, in baking and teas. In the past, it was carried in small bouquets by  fine ladies, used as table decorations and exchanged between lovers. Now the essential oils of the scented geraniums are extracted and used in toiletries, cosmetics and other flavor and fragrance products. 

Most geraniums are tender perennials, although some varieties withstand mild frosts in gardens in Zones 5-7. They come in lots of varieties and forms. Some are tiny,  a few inches high,  and some reach 5 or 6 feet in height. Some are erect, while others sprawl. Some trail, and some climb. Some have shiny green leaves; some are fuzzy and gray; and quite a few are variegated. Most are what botanists call semi-woody shrubs, although some of the smaller varieties arise from central rosettes.

Scented Geranium, Grapefruit Pelargonium 'Grapefruit' Grapefruit geranium has finely-cut, medium-green leaves that are rough to the touch. But give them a little rub and they'll release a grapefruit-citrus scent that fills a room. The plant has small pink flowers with small splashes of red in the center and delicate red stamens. Tender perennial. Overwinters outdoors in zones 8-10; should be potted and brought indoors in mid-autumn in colder climates.

While not generally showy, the flowers of almost all scented geraniums have five-petaled and in hues of rose, lavender, or white, usually appearing in clusters. Some varieties have bright red blossoms, others striped bi-colors, and still others produce flowers in solid colors. Some of these flowers are tiny,  like little stars, and some are large in proportion to the size of the plant. Some bloom almost continuously once they reach maturity; others have rather defined flowering periods. Quite a few are winter-bloomers. 

They bloom best when slightly pot bound, and it is best if they can be grown outdoors.  Any pot that provides good drainage will do.  Start with a 5" or 6" pot, and use a light potting mix.  You can  make your own using lots of perlite and/or sand. These plants are indigenous to a cool, semi-desert area and do not like wet feet, so water them well, and then let them dry out before watering again. In warmer areas (Zones 7-10), they may be planted outdoors after a period of acclimatization. Because of their lack of fussiness and tolerance of hot, dry conditions, scented geraniums are naturals in the summer garden. Scented geraniums need at least four hours of direct sunlight a day. 

The best way to deal with old and withered flowers is to deadhead, or pinch, the plants. Deadheading can be done at any time of year, by cutting or pinching dead buds. You can use any hand tool, pruning shears, or even scissors -- just be sure to avoid new buds and blooms. Deadheading will freshen the appearance of your garden, as well as promote longer lasting and more abundant blooms and prevent tall, leggy plants.

Some scented geraniums are large and bushy and will need regular pruning. Prune them on a regular basis with a pruning shears or scissors. Prune the green part of a stalk, rather than on the woody base of older plants. Remove stem tips above a leaf. Leave three or four leaves on the stalk so the plant will branch out from those points later.

Scented geraniums are light feeders.  Overfeeding will diminish their fragrance. Any commercial plant food balanced for blooming plants will do, used at about half the strength recommended for house plants.  Fertilize about every two weeks during periods of active growth, from March through October, but fertilize minimally, maybe once a month during the winter. If the plant is not blooming, check to be sure that the fertilizer being used is not too high in nitrogen. While it is essential for vigorous plant growth, too much nitrogen encourages leafy growth at the expense of blooms. 

It is almost impossible to overwinter geraniums outdoors north of zone 8, but quite simple to do so indoors. To overwinter entire geraniums or scented geraniums, dig them out of their beds or window boxes and place them in a bright spot inside. Make certain not to over water your plants during their stay indoors. Some gardeners prefer to grow cuttings of their plants indoors rather than try to overwinter entire plants. To root cuttings, remove bottom leaves and place in a glass of plain water on a windowsill. Make sure to protect all overwintering geraniums and new cuttings from freezing temperatures which can occur if your plants are left too close to icy windows.

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If  mottling, streaking, curling, or abnormal color patterns on the leaves occurs, scented geraniums may have been infected with a viral disease carried by insect pests. Once infected, there is no cure; infected plants should be destroyed to prevent the spread of the virus. A regular program of watering and fertilization will keep plants healthy and best able to ward off viral infection.

Common geranium diseases

The first step in combating a plant disease or pest is to identify it. Here are some descriptions of common geranium diseases and their recommended treatments:

Southern root-knot nematodes: These microscopic, soil-dwelling worms can attack geranium plant roots and cause stunted growth, wilting and yellowing. Infested roots will display knots or swellings. These worms are most troublesome in warm-winter climates and sandy soils. Nematode infestation can be prevented with a regular program of watering and fertilization in conjunction with the use of compost to introduce beneficial soil organisms and crab or shrimp wastes to amend the soil. These wastes contain a substance which encourages the growth of nematode-attacking organisms. Once infested, a plant cannot be treated; however, the organisms remaining in the soil can be killed by solarization. Cover bare soil with clear plastic sheeting for three to four weeks. The build-up of solar heat under the sheeting will kill most pests and weed seeds in the top few inches of soil.

Leaf spot: Leaf spot diseases develop during warm, moist weather and cause leaves to display brown or black spots with yellow edges. Eventually, the leaves may drop and the stems may rot. Cut off and destroy infected plant parts as well as seriously affected plants and any soil their roots touch. Since the diseases overwinter on plant debris, if leaf spot occurs, keep the beds clean and replace the mulch. Because the diseases can spread via water, infected tools, or unwashed hands, avoid splashing water on the foliage and keep your hands and tools clean. Spacing plants widely will promote good air circulation.

Botrytis blight: Also known as gray mold, this fungal disease is spread by wind-borne spores and thrives in cool, moist weather. Stems and flowers will rot and develop gray mold, especially during damp, cloudy weather. To prevent its spread, destroy diseased plant parts. To prevent infection, space plants widely to promote good air circulation and allow the soil to dry out between waterings.

Pelargonium rust: This fungal disease causes small, yellow spots on leaf surfaces or powdery, orange spores on the undersides of leaves. Badly infected leaves and plants should be destroyed. Plants with minor infections can be sprayed with sulfur. Watering early in the day, widely spacing plants, and avoiding overhead watering will help prevent infection.

Common geranium pests :

Geranium aphids: These tiny, soft-bodied, pear-shaped insects suck plant juices and can spread viral diseases. They can be controlled by knocking them off the plants with a strong stream of water, an application of insecticidal soap (pay special attention to treating the undersides of leaves), spraying with horticultural oil, and releasing beneficial insects, such as parasitic wasps, ladybugs, green lacewings, and aphid midges.

Caterpillars: Several species of caterpillars chew geranium leaves. Caterpillars can be handpicked and destroyed or they can be controlled with an application of Bt (Bacillius thuringeinsis) which kills caterpillars, but does not harm beneficial insects. Cultivating the soil in winter will kill overwintering pupae. Attracting or releasing beneficial insects such as ladybugs and parasitic wasps will also help to control caterpillars.

Other pests: Common garden pests, such as mealy bugs, whiteflies, and spider mites, can easily be controlled by knocking them off the plants using a strong spray of water, watering plants well during dry spells, and attracting or releasing beneficial insects. More severe infestations can be treated by applying insecticidal soap or neem.