In areas where drought and watering restrictions are common, you can add green by using drought tolerant ground cover. Ground cover is also used in areas that inhibit grass growth because of shade, the type of soil, or a rocky slope in the landscaping. Ground cover could also be used under shrubs to help keep weeds out of the shrub bed.
The carpet bugle (Ajuga reptans) is of the Lamiaceae family, and is an evergreen plant that thrives in USDA hardiness zones 3 to 9. It prefers partial shade and needs to be kept wet. This ground cover is best used near a water feature or in a shady area of the lawn. It is a fast grower, and grows up to 1 foot in height and 2 feet wide. The purple flowers bloom in May and June. It attracts butterflies and birds. The carpet bugle grows into a mat. It spreads via underground stolons (a stem that grows along the ground or just under the ground and that produces new plants).
The creeping lilyturf (Liriope spicata) has violet-blue flowers. Its green leaves form a dense cover 6 to 10 inches tall. It spreads quickly via rhizomes (underground stems that produce new plants) and is considered invasive. It thrives in USDA hardiness zones 6 through 10 and prefers partial shade. It grows up to 1 foot in height and 2 feet wide. Creeping lilyturf is a good groundcover for landscaping with alkaline and acidic soils, including clay, sand and loam.
The yellow archangel (Lamiastrum galeobdoln) is a semi-evergreen perennial that is often used as a groundcover because of its quick-spreading tendencies. The foliage is medium to dark green. It grows to about 1 foot in height to 1 ½ feet wide. The Variegata cultivar provides a mat of groundcover, while the Herman's Pride tends to clump more, thus spread less. The yellow archangel should be planted in partial sun, in well-drained soil. It flowers in April and May.