Express-News Weekly Column

Saturday, February 10, 2001

Submitted by Calvin Finch, Ph.D., Director of Conservation, SAWS, and Horticulturist

 

FAVORITE GROUNDCOVERS

 

            Asiatic jasmine in sun or shade, English ivy in the shade, and honeysuckle in the sun are traditional groundcovers used all over San Antonio.

There are three other plants that make wonderful xeriscape groundcovers that should be used more often to replace grass.

Dwarf Ruellia is a great groundcover in sun or shade. In full sun it blooms from mid-spring until late fall. Plants in deep shade will not bloom much. ‘Katy’ has a blue-purple flower and ‘Bonita’ is pink-flowered. The quarter-size blooms are utilized by hummingbirds. Deer do not seem to like the plant but will eat new growth in drought situations.

Plant one-gallon plants on two-foot centers. If the soil is relatively fertile, expect the plants to fill-in in one season. Four-inch plants will take twice as long to cover the ground. Incorporate two inches of compost and one cup of slow release fertilizer in the native soil across the planting bed and re-fertilize every February. The foliage will reach about 12 inches tall. The leaves are dark green, pointed and about three inches long. They make an attractive groundcover. Find ‘Katy’ and ‘Bonita’ Ruellia at all nurseries in the San Antonio area.

Red cascade rose is a groundcover with an attitude. Plant it over an area where you want to limit access by trespassers. It grows 18 to 24 inches tall and is heavily thorned. The canes become interwoven to form an impenetrable groundcover. Plant one-gallon red cascade on 12-foot centers and just get out of its way.

            Savage as red cascade is, it is also beautiful. The foliage in San Antonio is nearly evergreen and new growth has a red hue. The canes are covered with red quarter-size blooms from spring through fall.

I would think the ideal use for red cascade would be on sunny, bare hillsides such as road grades where the fast-spreading, quick-rooting canes would prevent the hillside from eroding and prevent trespassers from going up the hill from the road to homes above the road. Deer may nip at new growth in droughts but do not like the thorny stems.

            The Bexar County Master Gardeners grow red cascade at the SAWS Turfgrass/Groundcover Demonstration Site on Jones-Maltsberger just north of Loop 410. Visit the site from 9 a.m. until noon on Mondays when the volunteers are working and you can see the rose in action. They may even let you make a few cuttings to root for yourselves.You can also purchase plants from some area nurseries.

The third special groundcover is less savage than red cascade. The ‘Texas Gold’ columbine is a blooming groundcover derived from native columbines that does best under deciduous trees. It prefers winter sun but cannot survive summer sun. The blooms are described as shooting stars if you have a romantic bend. I used to describe them as golden spiders. A red-cupped version is called ‘blazing star.’ The flowers appear on 3-foot stems in March and April. They are favorites of the hummingbirds and, unfortunately, the deer like the flowers and new foliage (despite what the books say).

As pretty as the flowers are, I believe the foliage is the best part of ‘Texas Gold’ columbine. It resembles maidenhair fern and makes rolling mounds of foliage 8 to 14 inches tall under deciduous trees and even live oaks with tall or sparse crowns.

‘Texas Gold’ columbine is a weak perennial, meaning that 10 or 20 percent die each year in a typical bed, but it is an aggressive reseeder so beds on good sites remain covered. To encourage reseeding, a bed of columbines is one part of a xeriscape where mulch is undesirable.  The seed needs to come in contact with bare soil.

‘Texas Gold’ columbine looks too lush and fragile to qualify as a xeriscape plant, but it does most of its growing in the fall, winter and spring when rain is plentiful. In the summer the native columbines will decline on hot, dry sites to the point where some landscapers cut it back to the ground. On other sites where the soil and shade is deeper it hangs on to be relatively attractive all summer.

Like the dwarf Ruellias, ‘Texas Gold’ and ‘Blazing Star’ columbine should be available at all of the neighborhood nurseries in San Antonio. Plant it, you will like it.