With the concern over our water supply and the need to conserve, it is time to look at your garden and what you grow there.
Annual flowers are popular and easy to grow, but not all of them are water thrifty. Fortunately, one drought-tolerant flower has a little extra publicity this year to recommend it as a good choice for Utah gardens.
The National Garden Bureau did not have Utah's drought in mind when it designated 2002 as the "Year of the Vinca." It was thinking of the plant's many, many other virtues.
I have often considered this plant to be as close to an annual groundcover as you can get. The clear flower colors and waxy green leaves will cover the soil and make the plant an ideal choice for many uses. In addition to being a vigorous spreader, it is an excellent container plant and blends well with many other flowers if planted in the garden mixtures.
If you're not certain what plant I am writing about, you are not alone. Vinca is one of the best examples of why botanical names are important. It is known as Vinca, periwinkle and Madagascar periwinkle. Summer-flowering Vinca is genus Catharanthus. It prefers sunny, hot situations and blooms all summer until frost.
It is easily confused with two popular perennial groundcovers in Utah because all of them are members of the dogbane family Apocynaceae. The cousins, Vinca minor and Vinca major, are evergreen vining ground covers for shade that produce lovely, generally blue, flowers in spring. They are propagated from cuttings, not seed.
Another cousin, called Vinca vine, is a trailing vine with soft, variegated whitish-yellow leaves. It makes a popular container, window box or hanging basket addition. Vinca minor and Vinca major are also called myrtle in Utah.
The name confusion comes because botanists who first observed Catharanthus noticed that the flower closely resembled Vinca minor. They named it Vinca rosea and by the time they realized the differences between the plants, the name Vinca had already stuck.
The botanical name for summer flowering Vinca underwent several changes until it was finally classified as Catharanthus. The species name, C. roseus, means rose-colored, changed from the feminine rosea to the masculine roseus to match the gender of the Latin name of the genus. The genus name, Catharanthus, translates as "pure flower." Most modern cultivars are hybrids of C. roseus and other Catharanthus species.
Vinca is native to equatorial Madagascar so it grows as an annual in Utah. It has been popular for centuries throughout the world. Along with its cousins, it was a treatment for coughs and sore throats, eye and lung infections, diabetes and other maladies.
Modern researchers have extracted dozens of alkaloids from the plant. Some of them lower blood sugar levels and blood pressure and two alkaloids are sources of anti-cancer drugs. The advice from the National Garden Bureau is to leave the use of Vinca in medicine to the professionals and enjoy them in your garden for their beautiful flowers.
Thanks to extensive breeding, the Vinca color range is prolific. It now includes pink, deep rose, red, scarlet (the newest being 'Jaio Scarlet Eye,' a 2002 All-America Selections winner), white with red eyes, lavender blue with white eyes, peach, apricot, orchid, raspberry, burgundy and many other shades.
The 'Stardust' series has flowers with star-shaped white centers. Vinca grows 8 to 18 inches tall with a 1-foot spread, although trailing types spread to 2 feet. All Vinca flowers are simple: They are single, never double. Most modern varieties have overlapping petals.
Since you are too late to grow your own Vinca, look for plants at your favorite garden center. Select ones with bright green foliage. Avoid those with yellowed leaves. That indicates potential root-rot problems. Likewise, pass by leggy plants for compact, well-branched specimens.
Most Vinca are in flower when you buy them, so you can select by color. If you find plants in the bud, look at the variety name. Variety names are usually, but not always, a good indication of the plant's bloom color.
Plant Vinca when the temperatures warm up in late spring. Even if plants do not freeze, those that are started when it is still too cold grow poorly with few flowers. Vinca needs soil that drains well, but avoid soils that are too rich or fertile or the plants become leggy with few flowers.
Space plants 8 to 12 inches apart for a border edging or 6 to 8 inches apart to quickly cover an area as a ground cover. Be careful, though, with close spacing because lack of air circulation creates the potential for disease problems later on.
The plant loves heat and thrives on less moisture than most other annual flowers. To get the best water savings, use your Vinca with annual portulacas and California poppies. Add water-thrifty perennials including sedums, coneflowers, penstemons, yarrows, artemisias and pasque flowers for a showy garden that still conserves water.
Fertilize Vinca monthly with a small amount of granular or water-soluble fertilizer. Avoid overwatering as it will likely induce root rot or other problems. Other diseases should not be a problem this year because these drought tolerant plants are not bothered by most disease — if you water correctly.
Most pests seldom bother Vinca. The only insects I have seen are aphids. Wash them away with a stream of water from the garden hose. One very welcome bit of news for those who live along the foothills: Deer avoid eating Vinca so they are highly recommended to provide summer color in deer-prone areas.
While you may not be able to avoid the drought, you can select plants that are better adapted to it. Vinca is one of these. With some forethought and planning, you can use them to add outstanding color to your garden while helping conserve water.