Creeping Phlox Plant Profile

Creeping phlox

 

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Creeping phlox (Phlox subulata or P. stolonifera) is a familiar spring-blooming creeping plant that is frequently seen in rock gardens, growing from crevices in stone walls, or planted as a flowering ground cover. (A closely related plant that sometimes goes by the same common name is P. stolonifera, which is native to the Appalachian region.) Surely the best feature of creeping phlox is its flower production. The simple blooms are not only pretty, but they're also remarkably plentiful. The flowers are so densely packed that it can be hard to make out the plants' foliage from a distance. After the bloom is over, the tiny leaves remain green for much of the year.

Creeping phlox is sometimes known as "moss pink" or "moss phlox," based on its growth habit. This herbaceous perennial is semi-evergreen and is closely related to the familiar upright garden phlox (P. paniculata).

Botanical Name Phlox subulata
Common Name Creeping phlox, moss phlox, moss pink, mountain phlox
Plant Type Herbaceous perennial
Mature Size 4 to 6 inches tall; 18- to 24-inch spread
Sun Exposure Full sun
Soil Type Rich, well-drained soil
Soil pH 6.8 to 7.7 (slightly acidic to slightly alkaline)
Bloom Time Spring
Flower Color Pink, red, white, blue, rose, lavender, purple
Hardiness Zones 3 to 9 (USDA)
Native Area Eastern and central United States
Close-up of Creeping Phlox (Phlox subulata) Blossoms in Stonewall in Spring, Bavaria, Germany
David & Micha Sheldon / Getty Images

How to Grow Creeping Phlox

All in all, creeping phlox is one of the best perennials to grow in sunny areas. It requires minimal care, a medium amount of water, a bit of seasonal pruning, and perhaps an annual feeding. You can let it spread naturally so it covers a larger area (or simply becomes more brilliant) or trim it back during pruning to maintain a neater or smaller form.

As with many ground covers, grass and weeds growing up through the plant can be a major nuisance. It's best to start managing weeds early in the season before the phlox blooms or its foliage is at its fullest. Hand-pulling is the most effective method of weed control and also the safest for the plant. Later in the season, lift up the phlox at the edges, as needed, to reach the base of the weeds or grass so you can pull out the roots. If you neglect the weeding and let the grass get out of control, it might be easiest to pull up the phlox, clear the area of grass and weeds, and replant.

Light

A slope that faces in a southerly direction is ideal since these perennials grow best in full sun.

Soil

Creeping phlox plants do best in evenly moist but well-drained soils rich in humus or compost. They will do fairly well in clay soil. 

Water

Creeping phlox typically needs weekly watering, especially during the heat of summer. It is generally more drought-tolerant than most other phlox plants.

Temperature and Humidity

This perennial is fairly robust and can tolerate the hot environment created by rocks, gravel, or path surfaces. It does not need high humidity and generally handles dryness better than most other phlox plants.

Fertilizer

A feeding in late winter or early spring will promote growth and support a more robust bloom for your creeping phlox. Feed it with a slow-release fertilizer for flowering plants.

Propagating Creeping Phlox

To propagate creeping phlox plants, simply divide them in spring, immediately after they are finished blooming. Dig up the entire plant, including the root ball. Cut through the roots to divide the plant roughly in half, then plant each half as desired. Typically, you can divide a plant every two to three years without significant damage.

Pruning

Pruning creeping phlox is optional. After the blooming period, you can shear back the foliage to create a neater form. This also has the effect of making the foliage denser, which can enhance the plants' beauty as a ground cover for the summer months. Alternatively, you can skip the pruning and let the plants grow naturally. They do not need deadheading, although in some situations shearing can result in a second bloom.

Landscape Uses

Creeping phlox reaches, at most, 6 inches in height and can spread out up to 2 feet to form a mat. Since creeping phlox plants stay short and spread easily, they are widely used as ground covers. Although homeowners with flat land can use these plants as ground cover to form plant borders along lawns or walkways, their dazzling spring flower display is most easily appreciated when they are planted on slopes so they can be seen. These colorful, low-growing plants not only help prevent erosion but also blanket the slope with vibrant color in spring.

If your slope has a retaining wall installed at its base, the plants will spill right over the top—a truly wonderful look. This flowering ground cover is also often used in rock gardens, as an edging plant at the front of a flower border, or to fill the cracks between the stones of a stepping-stone path.

This plant attracts butterflies and is considered a relatively deer-resistant ground cover.

Common Pests/ Diseases

Creeping phlox is less susceptible to the powdery mildew that plagues other Phlox species, but spider mites can be an issue is hot, dry climates. Insecticidal soaps can be helpful for this problem, though application can be hard. Regular hard sprays of water can also dislodge the mites.

These plants can be susceptible to foliar nematodes in wet, humid weather. Nematodes cause lesions on the leaves of the plants that turn brown, then black. These soil organisms are hard to control. Diseased plants must be removed and destroyed, and the ground should be kept clean of debris.

Varieties of Creeping Phlox

The pure species form of this plant has lavender/purple flowers, but there are many cultivars available with flowers that are pink, red, or white. Some especially interesting varieties include:

  • 'Candy Stripe': This variety has pale pink flowers that are edged with stripes of white. It blooms for three to four weeks in mid to late spring.
  • 'Scarlet Flame': With dark red flowers, this plant is otherwise a typical creeping phlox.
  • 'White Delight': This variety with pure white flowers grows about 4 inches tall with a spread of a full 2 feet.
  • 'Emerald Cushion Blue': This cultivar is known for having very pale lavender flowers.