Ajuga

Image added by Joey Williamson, HGIC Horticuture Extension Agent, Clemson University, 06/13. Prepared by Marjan Kluepfel, HGIC Horticulture Specialist, and Bob Polomski, Extension Consumer Horticulturist, Clemson University. (New 12/98.)

HGIC 1102

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Three species of Ajuga are particularly useful to gardeners in South Carolina. These species grow in any reasonably well drained soil and although tolerant of full sun, growth is more rapid in partial shade.

Plant these perennials in spring or early fall 6 to 12 inches apart. Mow or trim away old flower spikes.

Ajuga repens (Bugle Weed)in bloom.
Ajuga repens (bugleweed) in bloom.
Joey Williamson, ©2011 HGIC, Clemson Extension

Ajuga Species

Carpet Bugleweed (Ajuga reptans): This is a very popular ground cover. It spreads quickly by runners, making a mat of dark green leaves that grow 2 to 3 inches wide in full sun and 3 to 4 inches wide in part shade. Selections with bronze- or metallic-tinted leaves keep color best in full sun. The flowers, usually blue, are borne on 4 to 5 inch high spikes. The plant flowers in early May to mid-June. If established plants are set apart in the spring, they will cover the soil in one growing season. Do not set the plants too deep. The crown should never be covered. In the spring or early fall, rooted "runner plants" can be dug from established plantings and replanted elsewhere.

Geneva Carpet Bugleweed (Ajuga genevensis): This is a perennial rock garden plant, 5 to 14 inches high. It does not spread by runners, and has grayish, hairy stems and coarse-toothed leaves to 3 inches long. The 2-inch tall flower spikes are usually blue, but rose and white forms are also sold. This upright species is becoming more popular because it spreads less vigorously than A. reptans. It tolerates more sun than other Ajuga species.

Upright Bugleweed (Ajuga pyramidalis): This is an erect plant, 2 to 10 inches high. It does not spread by runners. Stems, with long grayish hairs, have many roundish, 1½ to 4-inch long leaves. The flower spikes are 4 to 6 inches long and the large purple bracts appear to press against the blue flowers.

Growth Rate

Carpet bugleweed grows rapidly by producing mats of foliage in rosettes. "Runners" develop from the " mother" plants, take root and produce new plants similar to the growth habit of strawberries. Plant this perennial where its invasive qualities are welcome, such as on a bank or under trees. Do not plant it as an edging to the lawn or small islands of green foliage will soon appear in your lawn.

Cultivars of Carpet Bugleweed

Selections for Flower Color:

  • var. alba has creamy white flowers.
  • 'Catlin's Giant' has tall (up to 8 inch long) spikes of blue flowers and bronze-green foliage.
  • 'Pink Beauty' bears 4 to 5 inch long spikes of deep pink flowers.
  • 'Pink Spire' is a fine green-leaved cultivar bearing 7-inch long pink flower spikes.
  • var. rosea produces rose flowers.

Selections for Leaf Color: All have blue to violet flowers.

  • 'Atropurpurea' has dark bronze-purple leaves, which color best in full sun.
  • 'Bronze Beauty' is similar but has metallic bronze foliage.
  • 'Burgundy Glow' has foliage with shades of white, pink, rose, and green. In the fall the older leaves turn a deep bronze and the young leaves have a rosy hue.
  • 'Gaiety' has bronze purple leaves and lilac flowers.
  • 'Multicolor' (or 'Rainbow') is similar to, but more vigorous than 'Burgundy Glow'. The foliage colors are deeper.
  • 'Silver Beauty' has gray-green leaves edged with white.

Cultivars of Geneva Carpet Bugleweed

  • var. brockbankii is a smaller form of the species with deep blue flowers.
  • var. rosea has rosy-pink flowers but is otherwise identical to the species.

Cultivars of Upright Bugleweed

  • 'Crispa' has deep blue flowers and brownish red crinkly leaves with a metallic luster.
  • 'Pink Beauty' is 4 to 5 inches tall with light pink flowers in May and June.

Problems

In the South, several fungi cause crown and root rots, particularly in carpet bugleweed. Roughly circular patches of plants die out. Sometimes entire plantings may die. Planting in well-ventilated areas, dividing every 2 to 3 years, and application of a recommended fungicide help control this problem.

Ajuga is susceptible to the root-knot nematode (Meloidogyne incognita), which mainly occurs from the Midlands to the Low Country. Infected plantings will begin to thin out in spots and plants may die. Roots of infected plants will contain small knots caused by the feeding of these microscopic worms.

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