Common Name Creeping phlox, moss phlox, star rock phlox
Botanical Name Phlox stolonifera
Family Polemoniaceae
Plant Type Herbaceous, perennial
Mature Size 6–12 in. tall, 9–18 in. wide
Sun Exposure Full, partial
Soil Type Loamy, well-drained
Soil pH Acidic, neutral, alkaline
Bloom Time Spring, summer
Flower Color Purple, pink, white
Hardiness Zones 5–9 (USDA)
Native Area North America

Creeping Phlox Care

Here are the requirements to successfully grow low-maintenance creeping phlox.

  • Water every week or two if you haven’t had any rainfall to keep rich, slightly acidic soil moist.
  • Prune mature plants to keep them tidy unless you want them to naturally spread out to blanket an area.
  • Manage weeds in the area so creeping phlox does not have any competition accessing the soil’s nutrients and moisture.

Light

This plant grows best in full sun to partial shade. Too much shade can impede flower production.

Soil

Creeping phlox prefers soil that is rich in organic matter. It likes a slightly acidic soil pH but also can tolerate neutral and slightly alkaline soil. Moreover, it needs a well-drained soil.

Water

This plant requires a moderate amount of soil moisture, though mature plants do have some drought tolerance. Unless you have rainfall, it will generally need watering weekly, especially during the heat of the summer.

Temperature and Humidity

Creeping phlox plants are fairly hardy in their growing zones. They tolerate heat well and can handle some frost, though prolonged exposure to temperatures below 40 degrees Fahrenheit can damage the plants. Moreover, humidity is typically not an issue for the plants.

Fertilizer

Fertilizing in the late winter or early spring will promote growth and support a more robust bloom for your creeping phlox. Feed it with a general slow-release fertilizer suitable for flowering plants, following label instructions.

Types of Creeping Phlox

There are many varieties of creeping phlox, including:

  • Phlox stolonifera ‘Fran’s Purple’: This phlox features deep green leaves and rich purple flowers.
  • Phlox stolonifera ‘Home Fires’: Bright pink flowers adorn this variety.
  • Phlox stolonifera ‘Pink Ridge’: This variety has flowers that are similar in color to ‘Home Fires’.
  • Phlox stolonifera ‘Sherwood Purple’: Blue-purple flowers are featured on this plant.

Pruning

Pruning is optional on these plants. After the blooming period is over, you can trim back the foliage to create a neater form. This also will promote denser foliage, enhancing the phlox’s beauty as a ground cover. Alternatively, you can skip the pruning and let the plants grow naturally though you run the risk of poor airflow.

Propagating Creeping Phlox

Creeping phlox is best propagated via division. Not only is this a cost-effective way to get a new plant, but it also helps to rejuvenate mature and overgrown phlox. Typically, you can divide a plant every two to three years without seriously weakening it. Here’s how:

  1. Dig up the entire plant immediately after it’s done blooming, being careful to keep the root ball intact.
  2. Cut through the roots with a sterile, sharp spade to divide them roughly in half.
  3. Replant each half in an appropriate growing site, and water to lightly moisten the soil.

Common Pests & Plant Diseases

Spider mites can be an issue for creeping phlox in hot, dry climates. Insecticidal soaps are often helpful for this problem. Another option is to spray the plants regularly with a hard stream of water to dislodge the mites and keep them under control.

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

The good news is that creeping phlox is less susceptible to the onslaught of powdery mildew that plagues other phlox species. However, to stay safe from even small amounts of powdery mildew, this creeper plant still needs air circulation.

How to Get Creeping Phlox to Bloom

Bloom Months

Creeping phlox will start blooming in the late spring to early summer, depending on its climate. And it will stay in bloom for several weeks.

What Do Creeping Phlox Flowers Look and Smell Like?

Creeping phlox produces profuse clusters of sweetly fragrant flowers. The five-petal flowers have rounded, notched lobes, and they are overall fairly flat. The flowers attract butterflies and other pollinators. After blooming, the creeping phlox foliage remains green and attractive for much of the year before dying back in the winter.

How to Encourage More Blooms

Proper light conditions and a regular fertilization schedule will encourage the best blooms year after year. You do not need to deadhead these plants (remove the spent blooms), though in some cases this can extend the blooming period. Don’t do any pruning on your creeping phlox until it’s done blooming to avoid removing the flower buds.

Common Problems

Creeping phlox isn’t prone to many problems when grown in the conditions it likes. However, an improper environment can result in some common issues.

Leaves Turning Yellow

Yellowing foliage can be a sign of multiple issues, including diseases. But most often it’s an environmental issue, especially too little light, and overwatering. Watch your phlox throughout the day to make sure it’s not being shaded for too long. And make sure it has adequate soil drainage. The plant might need to be moved if it’s not in a suitable condition.

Spotty Leaves, Soft Stems, Mushy Roots

Creeping phlox may present with spotty leaves, soft stems, and mushy roots. This typically happens when creeping phlox is planted in poorly draining and excessively moist soil that does not have adequate air circulation. The result is mold and root rot. Provide proper airflow and pull and properly dispose of affected plants with root rot (do not compost).

Poor Blooming

Environmental issues also can result in poor blooming on a creeping phlox plant, especially if there’s too little light. Also, the soil might be too high in nitrogen, which promotes foliage growth at the expense of flower buds. In addition, if flowering has diminished on a mature plant, that’s often a sign it needs to be divided to become rejuvenated and bloom profusely again.

FAQ

    • Creeping phlox prefers full sun or partial shade, meaning at least roughly four hours of direct sunlight on most days.

    • Creeping phlox has a moderate growth rate, spreading by above-ground leafy stems, called stolons, to form its thick, lush mat.

    • Plant creeping phlox on flat ground, but it also looks beautiful spilling over rock ledges and garden bed edges. Creeping phlox helps with soil erosion when planted on slopes and hills.