Arachis glabrata, commonly called ornamental peanut grass and perennial peanut, is a native forage crop of Brazil that grows in the United States for erosion control and as an ornamental, perennial groundcover. Ornamental peanut grass is also as a replacement for grass in lawns where drought conditions exist. It is successfully used in urban landscapes, from medians to front yards. The plant is extremely drought-tolerant once it is established and provides a mat of healthy green foliage with summer blooms that range in color from bright yellow to orange. The flowers produce very little in the way of viable seed so the propagation of Arachis glabrata is done with the rhizomes of the plant. This attractive groundcover thrives in U.S. Department of Agriculture plant hardiness zones 7 through 11.
Perennial peanut rhizomes are available in mat sections or sod rolls. Some suppliers offer planted 4-inch containers or individual rhizomes. The mats and sod rolls are cut into sections of the desired size for your planting area. Generally, the rhizomes should be two to three years old before propagation. If you have an established perennial peanut plot, cut sections of the plot in late winter as though it were a mat or sod roll to generate more plants. Use a sharp sterile knife to cut straight down into the plant. Use a sawing motion to cut a line through the rhizomes. Cut another line that is parallel with the first. Make a third and fourth cut, connecting the first two lines at either end. Lift the cut section from the soil.
The perennial peanut rhizomes do not store well and must be planted as soon as possible, once you lift them from the soil. The rhizomes remain fresh for about 5 days when covered and stored in cool, dry conditions. If you have loose rhizomes, choose those that are at least 9 inches long and about 1/8 inch in diameter or thicker. Smaller rhizomes are more likely to grow weak plants.
Plant ornamental peanut grass when dormant, they generally enter dormancy after the first frost. First clear your planting site of all debris and vegetation. A legume, the ornamental peanut makes its own nitrogen, so the pH level of the soil should be around 5.5 to 6.0 for healthy growth. For propagation, sow individual rhizomes or sprigs you have cut from the sod roll or mat. Plant the sprigs or rhizomes about 2 inches deep and 18 inches apart. The closer together you plant the rhizomes, the faster the plant fills in the area. Tamp the soil into place to remove air pockets and firm the soil around the rhizomes. Wear gloves when working in the soil to prevent infection from bacteria.
Care of New Plants
Even though the perennial peanut is drought-tolerant, a good watering each day to a depth of 2 inches will help the plants grow. Once they are established, there is little you must do for the next two to three years. Mowing the plants promotes flower production. Frost may kill the vegetation, but the rhizomes will suffer little damage and grow another plant. When the plant rhizomes are two to three years old, you can propagate them for other areas of the landscape.