Geraniums run gamut

Although some people would contend that geraniums are nothing extraordinary, at some point nearly all gardeners develop a love for them. Whether ivy, scented or zonal, there is certain to be a geranium to suit your gardening tastes.

Most annual geraniums belong to the genus Pelargonium. The name is derived from the Greek word pelargos, meaning stork. If you’ve ever let a geranium flower go to seed, you understand the association: The seed pod of members of this genus have a rather peculiar stork beak-shaped appearance.

The common geranium and the zonal geranium — those plants with dark or colored rings on the leaves — are of hybrid origin. There are a variety of cultivars of Pelargonium x hortorum, which produce nearly every shade from white to red, including plants with violet or bicolor flowers. Some cultivars bear flowers in a single bloom, while others are semidouble and double.

These geraniums are popular as houseplants, but also have use as plants for bedding, border and hanging baskets.

Another geranium popularly used in hanging baskets is the ivy geranium, Pelargonium peltatum. As its name implies, this plant has a vining or trailing growth habit. The leathery leaves of the ivy geranium are thick and shiny; the flowers more delicate than the common geranium.

Finally, one of the most popular — and unusually fragrant — groups of geraniums is the scented geraniums. You may see this group of plants identified simply as Pelargonium spp. in references, because a range of species produce scents, including pine, rose, apricot, strawberry, peppermint and even coconut!

These scented geraniums are indigenous to South Africa, but have been grown in this country since colonial times. Essential oils are extracted from these plants and, along with dried geranium leaves, are used in potpourris and herbal mixtures. Herbalists use scented geraniums as astringents, and some even recommend their use internally for various digestive problems. Before you make teas, cakes, cookies and jams (all of which may be made with additions of scented geraniums) be sure to consult a reference.

Geraniums of all sort are relatively easy to grow. Sun and moist, rich soil is all that is needed. Geraniums enjoy cool roots, so in the garden, be sure to apply a mulch. Limit watering of plants to just what is needed; too much soil moisture and poor air circulation may lead to fungal problems, including Botrytis and Fusarium wilt.

Your questions

Q. During the ice storm I lost several houseplants to the cold. Some didn’t die, but their leaves, especially around the edges, turned dark green and wilted. The leaves haven’t totally died. Other leaves have small white bumps on the undersides, which I assume is a gall from some type of bug. Should I hope these damaged plants come back, or should I dispose of them before they infect my other plants? — S.F., Winslow

A. It sounds like the freezing temperatures caused the dark discoloration of some of your plants’ leaves. It’s safe to assume that if vigor hasn’t returned to the leaf by now, it won’t.

As for the “bumps,” it is possible that they may be a gall, but even more likely, you’ve spotted some oedema, a condition which occurs in plants as a result of overwatering. Oedema, or edema as it is sometimes spelled, occurs when a plant cell’s capacity to hold water is exceeded and the cell walls burst. In mass, this creates a bumpy texture on the undersides of leaves.

Thus, even though the plant as a whole may survive, localized leaf damage will occur. Once I spot oedema, I remove the affected leaves because the damaged tissue may be more susceptible to the onset of disease, putting an otherwise healthy plant at risk.

Q. What’s the best time of day to water the garden? — L.K., Brooks

A. Although watering the outdoor garden is months away, this is a great question any time of year. The best time to irrigate is either first thing in the morning, before the sun intensifies (say, before 9 a.m.) or after the sun’s intensity diminishes significantly (perhaps after 5 p.m.). During the summer months, these times of day allow plants to absorb and retain moisture without having to relinquish it to the sun’s pounding rays through the process of transpiration.

Diana George Chapin is the NEWS garden columnist. Send horticulture questions to Gardening Questions, c/o Maine Weekend, Bangor Daily News, P.O. Box 1329, Bangor 04402-1329. Selected questions will be answered in future columns. Include name, address and telephone