The International Herb Association has designated scented geraniums as their Herb of the Year for 2006. Scented geraniums, in the genus Pelargonium (which includes over 200 species, some scented and others scentless) are relatives of the common red, pink or white flowered summer annual zonal geraniums (derived from the relatively scentless pelargonium, P. x hortorum). They are grown more for the highly aromatic foliage than the flowers. Plants have a wide range of leaf types which are used for making potpourris, sachets, and flavorings. The scent is contained in oil produced in special glands at the base of the leaf hairs. Bruising or crushing the leaves breaks open the glands, releasing the scented oil.
Scented geraniums were originally brought to Holland and England from South Africa in the mid 1600’s. Since then, breeding and hybridization has resulted in hundreds of varieties, in a wide range of shapes, sizes, and color, and in rose, mint, spice, fruit, and pungent fragrances. The scented geraniums are a very large group of plants with many species that are categorized by scent (the names are sometimes confused however, with true species, cultivars, hybrids all mixed together). Some of the more common ones include:
- Apple-scented geranium, P. odoratissimum, is a trailing type with heart-shaped, apple-scented, grey-green ruffled leaves and white flowers.
- Coconut-scented geranium, P. grossularioides, is more cold hardy than many other species. The low growing rosette of deep green rounded leaves produces tiny magenta flowers and has a pleasant scent that not everyone describes as coconut.
Lemon-scented geranium, P. crispum, has a clean lemon scent from the small wrinkled, fan-shaped leaves. It bears tiny purple-pink flowers and does well in containers.
- Lime geranium, P. nervosum, has ruffled, round, light green leaves and lavender flowers. It flowers freely and self-seeds.
- Nutmeg-scented geranium, P. fragrans, is a small plant with grey-green leaves with a nutmeg-pine scent and small whitish flowers with pink veins.
- Oak-leaf geranium, P. quercifolium, has lobed, dark green leaves with an almond or incense scent and small rose colored flowers.
Peppermint geranium, P. tomentosum, is a spreading or trailing type with medium- to grey-green, lobed leaves and white flowers with a reddish center. While the leaf has a minty scent, the flavor has other overtones so real mint (Mentha spp.) is best used for cooking.
- Rose-scented geranium, P. graveolens, has spicy rose-scented foliage with small clusters of pink flowers among the large, lobed, dark green leaves and is well suited to growing in containers. ‘Robert’s Lemon Rose’ is a common variety with a strong lemony rose scent. ‘Snowflake’ is a variegated form.
Other scents include apricot, chocolate, ginger, orange and pineapple – and at least 50 other according to some lists. Another scented geranium sometimes sold as “the mosquito plant” or “citrosa” (as P. citrosum ‘van Leenii’ or P. citronellum) is marketed as a mosquito repellant, but researchers at the University of Guelph in Ontario, Canada found it had no effect on mosquito biting. Supposedly the plants were developed by introducing a gene from the tropical grass Cymbopogon nardus (which is used to produce citronella commercially) so citronella oil would be made by the geranium leaf. Chemical analysis of the mosquito plant revealed only trace amounts of citronellol, the main compound in citronella oils, and chemically it was barely distinguishable from the normal rose-scented geranium. Even real citronella isn’t an effective repellent sitting in a pot; the leaves must be crushed to release the essential oils. Crushed citrosa leaves rubbed on the body does offer a little short-term repellency, but other plants, such as lemon thyme (Thymus x citriodorus) or lemon balm (Melissa officinalis) even better.
Many scented geraniums have soft, finely textured foliage. The individual leaves vary in shape from deeply cut and lacy or frilled to rounded. Plants may have dark green, pale green or green-and-cream variegated leaves that vary in size from ½ to three inches across, depending on the species or variety.
The flowers of scented geraniums are not nearly as showy as their garden annual relatives – often described as small and whimsical. Both kinds have the same type of individual flowers typical of the genus. The petals are arranged with two upper petals and three lower petals, with the upper two generally larger and more richly colored than the others. They range in color from white to various shades of pink and red and usually have no fragrance.
Scented geranium plants can grow from 1’ to 5’ tall, developing tough, woody stems when older. Since many are frost tender and some will tolerate light freezing but not sustained cold, in the Midwest they are treated as an annual outdoors or can be grown year-round as a houseplant. There are trailing forms that can be used in baskets or as ground covers, while others are good for borders.
When grown outdoors, scented geraniums do best in sun to part shade. They prefer well-drained, fertile, moist soil. Do not overwater; water only when the soil is dry. Grow them as a summer bedding plant or in containers or hanging baskets to bring inside for the winter. Place near a path, so the fragrance is released when someone walks by and brushes against the leaves. Prune as needed to encourage dense growth. Plants grown indoors should be fertilized regularly to encourage leaf growth.
Scented geraniums can be found at most local and herb nurseries. Many types can be grown from seed, but plants grown from seed will not come true to a named cultivar, and the scent will vary. Stem cuttings are the easiest way to propagate scented geraniums. Cuttings can also be taken of garden plants in late summer to overwinter indoors. Some varieties may root in a glass of water, but greater success is obtained by placing the cuttings in damp perlite or other well-draining soilless mixtures.
The leaves can be harvested any time and used fresh or dried. They may be used in cooking, as an infusion of fresh leaves added to jellies, teas, vinegars, or desserts (such as scented sugar used in ices or syrups). Rose-scented geranium leaves are the most frequently used; one classic recipe for pound cake uses a layer of fresh leaves in the bottom of the cake pan. More frequently the leaves are used as an addition to sachets and potpourris, especially to scent clothes and linens. Fresh leaves can be added to bath water. The oils in the leaves are often distilled to make perfume. The essential oil from P. graveolens is sold commercially as a food flavoring and additive as geranium oil and rose geranium oil.
– Susan Mahr, University of Wisconsin – Madison
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