Rock Phlox Phlox subulata

Moss phlox is a spring-blooming herbaceous perennial that has a dense, spreading, mat-like forming habit. It grows up to 6 inches tall and up to 2 to 3 feet wide. The leaves are green, linear to awl-shaped, and needle-like. The blooms appear in loose clusters of tubular 3/4 inch flowers in shades of pink, lavender, reddish-purple, and occasionally white.  It is noted for its creeping habit and the profuse carpet of flowers that bloom early to mid-spring and then sparsely until frost. The foliage mats are cushion-like, resembling moss, hence the common name of moss phlox.

It is native to the central and eastern portions of Canada and the United States. Moss phlox is found in dry rocky, or sandy areas, savannas, rocky ledges, slopes, clearings, and open woodlands. It is native mainly to the Appalachian Mountains. 

The specific epithet, subulata, translates as "awl-shaped" which references the leaves.

Moss phlox prefers moist, well-drained, humus soils, and full sun. It flowers best in full sun but in hot humid summers, the plant appreciates some dappled sun. They like sandy and gravely soil and can tolerate hot and dry conditions better than other species of phlox. It is good practice to cut back the stems by 1/2  when flowering is completed to help maintain their shape and encourage dense growth. It is tolerant of deer, erosion, drought, and air pollution.

The stems of moss phlox are green when young, becoming tan and woody with age. Older plantings thin out as new growth spreads away from the center of the plant. It has many cultivars with vibrant pink, red, lavender, blue-purple, or white flowers that cover the plant from late April to early May. 

Garden uses include rock gardens, edgings, foundation plantings, or ground covers in sunny areas of woodland gardens, slopes, native plant gardens, or naturalized areas. It may also be used to drape slightly over a  low rock wall. 

Seasons of Interest:

Blooms:  Spring     Foliage:  Spring, Summer, and Fall

Quick ID Hints:

• creeping, dense, mat-like herbaceous perennial, up to 6 inches tall and 2 to 3 feet wide
• opposite, linear to awl-shaped, needle-like green foliage up to 1-inch long
• loose clusters of tubular flowers, 3/4-inch wide, five flat notched petals of lavender, pink, white, or red

Insects, Diseases, and Other Plant Problems:  Moss phlox is relatively pest and disease-free and has moderate drought tolerance. It is resistant to powdery mildew, unlike most other species of phlox. Spider mites can be a problem in hot, dry conditions, and nematodes can cause damage to the leaves in wet and humid conditions. Rabbits may feed on the foliage, but it is less palatable to deer. Some cultivars have shown good resistance to phytophthora and southern blight. See Phytophthora Root and Crown Rot in the Landscape.

VIDEO created by Andy Pulte for “Landscape Plant Identification, Taxonomy, and Morphology” a plant identification course offered by the Department of Plant Sciences, University of Tennessee.

More information on Phlox.