Plant Answers

Weekly Express-News Article
By Calvin R. Finch, PhD, SAWS Water Resources Director, and Horticulturist
Saturday, September 8, 2007

“Groundcovers”

A lawn is a groundcover, but there are other choices as well. The “other” groundcovers have some advantages over a lawn. They are usually less work than a lawn. No weekly mowing, less fertilizer, and less pesticides. Most groundcovers also require less water than a lawn. Once established many groundcovers do not require irrigation and others prosper with watering once per month. A major advantage of some groundcovers is that they have more shade tolerance than any lawn grass. Some groundcovers even have attractive flowers.

The most versatile groundcover has to be Asiatic jasmine. It grows equally well in sun or shade, is a good xeriscape plant, is evergreen, and can be manicured or grown in more natural manner. The major limitation of Asiatic jasmine is that it is slow to be established.

If you establish Asiatic jasmine with inexpensive rooted cuttings it can take two to three full growing seasons to establish the bed. During that period of time it needs to be watered every two weeks and weeded.

It is easier to establish Asiatic jasmine by using one quart or one gallon container grown plants placed on two foot centers in the planting bed. In the autumn this is especially desirable because area nurseries usually have sales on Asiatic jasmine and other groundcovers.

The easiest planting technique is to kill your lawn grass with glyphosate (Round-up) and plant the groundcover right into the killed sod. The killed sod serves as a mulch and helps keep out weeds while reducing evaporation. If the groundcover is planted into an unsodded area, add one – two inches of compost, one cup of winterizer fertilizer per 500 square feet, till everything into the soil, rake smooth and plant the groundcover. A one inch layer of a fine groundcover such as shredded leaves or cocoa shells also increases growth.

Asiatic jasmine can be grown as a rolling groundcover 12 – 16 inches tall or cut flat across with a string mower. Edges can be rounded or very square. Even the most manicured look only requires attention every month.

In extremely cold winters the jasmine bed may show some freeze burn. The easiest way to clean it up is to run your lawn mower over it in February at the highest setting. This tactic also works on naturally grown beds to reduce height and remove stems that are growing in an undisciplined manner.

A second excellent groundcover is dwarf Mexican petunia. The plant grows to 12 or 14 inches tall, is evergreen, and can tolerate shade or sun. Dwarf Mexican petunia can not be trimmed to many heights with square edges, but it does have an attractive bloom. The ‘Katy’ selection is purple/blue and ‘Bonita’ has a pink flower. There is also a white flowered selection. Dwarf Mexican petunia can bloom up to six months of the year. The hummingbirds visit the flowers for the nectar. Deer eat the plants in my neighborhood during droughty periods, but pass them up during wet periods like now. Dwarf Mexican petunias should be planted on 18 inch centers. On well prepared soil as described in an earlier paragraph it fills in thickly after one and a half growing season.

Monkey grass and its larger cousin liriope make excellent groundcovers for shady sites. It looks like grass, is evergreen, is very drought-tolerant, and only grows to a specified height. These grass like groundcovers also are very drought-tolerant. Plants can be purchased in four inch containers (one gallon for liriope). Plant the smaller monkey grass six inches apart and liriope 18 inches apart. The monkey grass is almost as slow as Asiatic jasmine to fill in, but once it is established it makes a very tight groundcover. In fact, one of the best ways to obtain planting stock is to find an established bed and harvest plants in a four inch strip with a sharpshooter across the bed. The strips fill in one growing season.

Other groundcovers to consider are Texas gold columbine, (deciduous shade) trailing lantana, (sun) English ivy, (shade) cemetery iris, (sun) daylilies, (sun) prostrate rosemary, (sun) and spreading juniper (sun).

Most groundcovers become so thick, weeds are not a problem, but while you are establishing the beds or in other cases where Bermuda grass or St. Augustine grass invade the bed, a post emergent contact herbicide for grass works very well. Some of the available brands are Vantage, Over the Top, Grass be Gone, and Poast.