June 6, 2001
Stillwater Gazette
Betsy Halden

Scented geraniums

Most gardeners like geraniums. Geraniums are popular plants for containers, window boxes, and garden borders. They come in an interesting array of colors and sizes. Martha Stewart extols them. But did you know that the plants which we purchase at our Valley garden centers are not really geraniums? Zonal, ivy, and Martha Washington geraniums are actually members of the genus Pelargonium. Pelargoniums are tender plants that originated in South Africa. There are about 208 species of pelargoniums that can be divided into four groups; zonals, ivies, Martha Washington, and the scented types. Geranium is the common name for the group of plants known in Latin as Pelargonium. Further complicating matters is the fact that geranium is both the common and proper name for a group of 260 other plants that are native to the temperate regions of the world, many of which are known as the cranesbill geraniums.

The pelargoniums are a group of plants that many gardeners have grown successfully. One group from this genus, the scented geraniums, have been less popular for unknown reasons.

The scented geraniums are a group of over 50 species and varieties that have interesting features. There are four major categories of scented geraniums. The citrus types, such as lemon, lime, ginger, orange and strawberry; the rose types, including old-fashioned rose, cinnamon and eucalyptus. The third group includes the pungent types, nutmeg, pine, peppermint and Old Spice. The fourth and final group includes any that do not fit into the previous three groups, such as apple, coconut and balsam. One summer I bought a “mosquito” geranium. When the leaves were rubbed they smelled like citronella. I had visions of our new geranium plant repelling mosquitoes from our deck. It didn’t. It only smelled like citronella.

In addition to smelling good, many of these plants have interesting cut leaves and varying textures. One reason that these scented plants are less popular than the other pelargoniums is that they tend to have smaller, less showy flowers. They can be put to good use in our gardens, however. The colors of the foliage range from dark green to silvery gray. Some of the plants grow quite tall which makes them ideal for adding height to the back of the flower bed.

Many people ask why and how scented geraniums smell. The why is answered by understanding that the scent is a defense to prevent animals from grazing on the plant. The how is explained by understanding that the geranium leaf has tiny hairs on it. Among these hairs are tiny beads, and when the leaves are disturbed the beads break and scented oils are released.

Although some gardeners try to overwinter their geraniums, it is iffy business. Geraniums need cool temperatures and bright light to successfully winter indoors. They should not be over-watered nor over-fertilized. . It may be easier to start over with new plants in the spring.

Buckthorn invasion
Did you know there are communities in southern Minnesota that have called out the National Guard to help fight buckthorn? We took out buckthorn from our hillside last fall. This spring new sprouts are popping up in new places. Some of our neighbors grimly confess to pulling out saplings anywhere they find them. Buckthorn invades. Its dense, fibrous, black root system allows it to compete with more desirable native trees and shrubs for nutrients.

As a quick review, common buckthorn is a small, shrubby tree. Its poisonous, small black berries are often mistaken for wild cherries. It is a non-native plant that is a weedy nuisance. Buckthorn twigs are tipped with a short, sharp thorn. The buds are slightly curved and pressed to the stem. The leaves are dark green with curved main veins. The leaves hang on late into the fall without changing color. The berries are black and contain several seeds. The juice is greenish-black. If you see seedlings coming up, promptly remove them.

In the past, common buckthorn was widely planted for formal hedges. It is now more commonly seen as a wild plant. Birds spread the seeds after eating the plentiful berries. It is no longer recommended for plantings. It is illegal for nurseries and garden centers to sell it.

There is excellent information about buckthorn available on the web. Go to extension.umn.edu/projects/yardandgarden/ygbriefs/h402buckthorn-common.html.

If you have a question about garden or landscape plants, insects, wildlife, plant disease, soil testing, call the Yard& Garden Line at 612.624.4771 in the metro area. Call 1.888. 624. 4771 in greater Minnesota.

Betsy Halden is a Master Gardener with the University of Minnesota Extension Service. University of Minnesota Extension Service materials were consulted in the preparation of this column. You can reach Betsy Halden at eahalden@comcast.net