A number of groundcovers work well in areas of the yard such as shady spots and slopes, where grass may not be the best choice. In my last article I featured mondo grass, a clumping-type groundcover that is often used in very shady areas.

Wedelia is another popular groundcover that has multiple uses. This spreading-type plant is a vigorous, creeping, herbaceous groundcover native to tropical America. It was first introduced into Hawai'i in the early 1970s and has since been extensively used in the landscape. Wedelia forms a dense mat of oval or three-lobed, hairy, bright green leaves 1 to 3 inches long. Its stems root at each node as the vines spread along the ground. Small yellow daisy-like flowers extend above the leaves and are produced throughout the year.

When left unattended, wedelia can grow 18 to 24 inches high, but its height can be reduced and maintained at much lower levels by periodic cutting with a string trimmer or a rotary mower. It will flower at any height but will usually have the most blossoms when maintained at about 4 inches.

Wedelia does well in sun or shade, but full sun produces the best flowering and densest coverage. It is also salt-tolerant enough to be used near the seashore. Like many vine-type groundcovers, it does not hold up well under even moderate foot traffic.

Although wedelia has become one of the most common and dependable groundcovers in Hawai'i, but it is very aggressive and is not a plant for small confined areas. It can and will over-grow neighboring areas including low-growing shrubs, lawn areas and into woodlands. Growth can be controlled by carefully managing water and nitrogen fertilizer. Water and fertilize only enough to maintain growth and color. Periodic trimming or mowing is also important to keep it within its boundaries.

Because of its heavy rooting characteristics, wedelia is popular for erosion control on slopes and banks.

Wedelia has few insect or disease problems. The main problems usually come from weed invasion. The most difficult weeds to control are the broadleaf type. Since wedelia is also a broadleaf plant, any herbicide that kills these weeds will also severely damage the foliage of the wedelia vines. Hand weeding is the most effective control of existing broadleaf weeds.

Another troublesome group of weeds are the sedge-types — nutgrass, McCoy grass and kylinga. These can normally be controlled with the selective herbicides Image or Manage. However, both of these will severely damage wedelia. Hand weeding or very careful spot spraying with Roundup or Image is the most effective control of these weeds in wedelia.

The primary problem associated with wedelia comes from its rampant growth.

It should not be used in small or confined landscape situations unless it is constantly maintained by mowing or trimming.

Jay Deputy is an education specialist in landscape horticulture and turf at the University of Hawai'i-Manoa, Department of Tropical Plant and Soil Sciences, and state administrator for the Certified Landscape Technician Program sponsored by the Landscape Industry Council of Hawaii. Got a lawncare or turf question? Send correspondence to deputy@hawaii.edu.