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). Plant creeping phlox in spring, after threat of frost has passed. It has a moderate to fast growth rate.
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
Toxicity:
Non-toxic
Creeping Phlox Care
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.
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.
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.
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.
Landscape Uses for Creeping Phlox
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 and 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 difficult. Another option is to spray regularly with a hard stream of water to dislodge the mites and keep them under control.
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.
Creeping Phlox vs. Tall Phlox
In contrast with its ground-hugging relative Phlox subulata, Phlox paniculata, or garden phlox, is sometimes referred to simply as "tall phlox." These perennials are tall enough to be inserted into the middle or back row of a bed of mixed perennials without getting lost. If spring is prime time for Phlox subulata, then the best time for tall phlox to shine is the summer: It's an old standby for the summer garden, a colorful contributor to your yard's beauty long after many other perennials have petered out. As you can imagine, this makes it a valued plant among those looking for a continuous sequence of bloom.
The leaves of Phlox subulata and tall phlox are so different from each other that one would be hard-pressed to identify them as related species in the absence of their flowers. Phlox subulata has needle-like leaves, some of which remain green throughout the winter. The leaves of tall phlox are much larger and die back at the end of the growing season; they are narrow at both ends and flare out in the middle. The leaves of Nora Leigh offer a nice twist in that they are variegated.
The tall phloxes are cold-hardy plants, but they have a tougher time coping with extreme heat. They are susceptible to powdery mildew, which is more difficult to combat the hotter it gets outside.