Creeping Phlox (Moss Phlox) Guide: How To Grow, Care for Groundcover

What Is Creeping Phlox aka Moss Phlox (Phlox subulata)?

Phlox subulata, usually referred to as Moss Phlox or Creeping Phlox, is a flowering perennial plant with a low, spreading growth habit.¹⁷ This spring-blooming ground cover plant creates a dense mat of colorful small blossoms that range from white to purple to blue and red.

Creeping Phlox is often used along borders and on hillsides, as it can thrive in coarse, rocky soils.¹⁷

P. subulata is one of nearly 70 species in the Phlox genus of the Polemoniaceae family,²⁰ all of which are native to North America. Many species have a mounding habit, and most produce bright bursts of color, hence the Greek-derived genus name meaning “flame.”^{12, 14}

When To Plant Creeping Phlox and How To Plant Creeping Phlox

There are several options for when to plant Creeping Phlox, depending on the climate.

In climates with mild winters, autumn might be the ideal time for when to plant Creeping Phlox for the best yield. In an area with harsher winters, wait until spring, after the last frost, before planting Creeping Phlox.⁷

(Image: t.kunikuni⁴¹)

Curious about how to plant Creeping Phlox? Most first-time growers will probably plant Creeping Phlox from a nursery-bought seedling.

The most important planting tips for Creeping Phlox to remember are that the root ball of the seedling should not be completely below the soil surface, as pooling water can lead to fungus and rot problems. Keep it elevated slightly to allow water runoff, and mound the dirt up around it.

Another thing to remember is how far apart to plant Creeping Phlox. Phlox likes to spread along the ground, so allow a diameter of 2 feet for the plant to reach its mature breadth.⁷

How To Propagate Creeping Phlox (Growing a Creeping Phlox From a Seed, Cutting, or Seedling)

There are a few methods for how to propagate Creeping Phlox, and growing a Creeping Phlox from a seed, cutting, or seedling are all possibilities. Growing from a seedling was discussed in the previous section, but growing from seed is another popular way to propagate moss phlox.

When growing from seed, gardeners can direct sow into the ground in late spring. In colder climates, it may be advisable to start the seed in indoor containers in the spring about 7 weeks before the last frost.

Bury the seed in the growing medium very shallowly and place the containers in a well lit location. Successful seeds should germinate within 2 weeks.

Water gently or mist frequently to keep the small sprouts moist. Transplant the sprouts when soil temperatures are consistently warm.

Homeowners who are already growing moss phlox in their backyard garden may have an easier time propagating phlox from softwood cuttings. Division is one of the most efficient ways to grow Creeping Phlox, and softwood cuttings should be taken from new growth in the spring.

Select shoots that are non-flowering, and plant them in a rooting medium until roots form.⁷ After significant roots form and the plant has adjusted, it can be transplanted into warm soil.

Best Growing Conditions for Creeping Phlox

The best growing conditions for Creeping Phlox are in full sun in well-draining soil with a neutral pH. Moss Phlox does well in coarse, grittier soil, and it prefers when it has space to spread a couple of feet outwards.

Some excellent places in the home garden to plant Creeping Phlox are on hillsides, along pathways, flower bed edging, and in rock gardens!

Add phlox to butterfly gardens for some extra color, fragrance, depth, and variety!^3,11

Creeping Phlox Growing Zone

Creeping Phlox is a considerably hardy plant and will tolerate persistent low temperatures through the winter months. Gardeners who are curious about growing zones for Creeping Phlox (where to grow and where not to grow) will be comforted by the wide range of climates in which this herbaceous perennial can thrive.

Creeping Phlox growing zones range from 3a, with frigid temperatures as low as -40 degrees Fahrenheit in northern Minnesota, North Dakota, and even Alaska all the way through 9b where winter temperatures rarely drop below freezing, typical of southern Florida, Texas, and California (See USDA Plant Hardiness Zone Map).^17,21

Creeping Phlox Growth Rate

Many people have wondered how long it takes to grow Creeping Phlox.

Creeping Phlox growth rate is moderate to fast, and moss phlox grows at a steady pace until it reaches its mature size at around 2 to 3 years of age.¹⁰

Creeping Phlox Care

Part of the joy of growing moss phlox is the simplicity of Creeping Phlox care. In fact, once the plant’s roots are established, it is hard to find a more low-maintenance plant.

Watering needs for Creeping Phlox plants are fairly low, but they do need regular watering throughout their first year, once per week on average. As with any other plant, those grown in containers require more water than in-ground plants as their roots are not as deep.³

Although Creeping Phlox suppresses weeds quite well on its own, weeding early on while the plant is still becoming established can help increase the success rate for the phlox. Learn to identify weeds by photo and check out this organic weed killer recipe!

Caring for Creeping Phlox in Winter

Phlox subulata is pretty tolerant of cold temperatures, an added benefit of this particular species. Tending Creeping Phlox in winter can be as easy as adding a layer of mulch to insulate the roots.

In warmer climates, even this step may not be necessary. Some people like to prune away any dry or brown foliage before new spring growth arrives, but this is not obligatory.¹

How To Stop Creeping Phlox Disease

Another great quality of Phlox subulata is the fact that it is fairly resistant to both pests and diseases. In fact, this particular species is not even impacted by powdery mildew to the same extent as other Phlox species. However, problems do sometimes develop, and it is helpful to know how to stop Creeping Phlox disease if and when an issue arises.¹⁷

The most common pests of the Creeping Phlox include spider mites and nematodes, which are known to damage leaves. Natural pest control for Creeping Phlox includes soil moisture control, as too little or too much moisture makes the plant vulnerable to pests.

Insecticidal soap can be used to control pests, and good plant hygiene focused on removing visible pests and diseased plant parts is crucial!²

Moss phlox can be impacted by fungal diseases such as black root rot (Thielaviopsis basicola),²² Fusarium,²³ Botrytis,²⁴ Myrothecium,²⁵ and Alternaria,²⁶ which can all be fatal for plants. The best Creeping Phlox disease prevention is to plant cultivars that are disease resistant.

Always ensure that the growing medium or soil is well-draining and the plant has good air circulation, and do not over-fertilize! Infected plants should be removed before they can contaminate neighboring plants.⁹

Companion Plants for Growing Creeping Phlox (Best Perennial Flowers To Grow With Creeping Phlox)

Creeping Phlox is known as one of the plants that attract hummingbirds, butterflies, and bees, so adding other pollinator friendly flowers can create an ideal haven.

(Image: Lebuert⁴⁰)

When looking at companion plants for growing Creeping Phlox, search for varieties that thrive in sunny conditions and drier soil. Choosing plants that bloom slightly before or after phlox can keep the garden colorful throughout the growing season.

Some excellent options include:³

• Spring bulbs which bloom before the phlox
  • Daffodils
  • Tulips
• Plants that thrive in rocky, dry soil
  • Columbine
  • Succulents
  • Lavender
• Late blooming perennial flowers
  • Daylilies
  • Echinaceas

How To Identify Creeping Phlox

Knowing how to identify Creeping Phlox is handy for many reasons, but mostly because proper identification informs proper care.

(Seed Image: David J. Stang³⁴)

Moss Phlox has some distinct qualities that set it apart from other Phlox species, particularly where the leaves are concerned. These are discussed in the following sections.

Identifying Creeping Phlox Flowers

The average Creeping Phlox flower is a symmetrical, 5-petaled beauty, though plenty of blossoms have only 4 petals. Each individual flower is less than 1 inch in diameter.

The blossom is tubular at the base but opens to a flattened, round disk composed of 5 elongated, notched petals. The petals are paddle-shaped and may be a single solid color, but more often are bi-colored with a darker burst around the center.

Phlox flowers bloom for 3 to 4 weeks in late spring in shades of white, pink, purple, red, and blue.¹⁷

Identifying Creeping Phlox Leaves

Creeping Phlox leaves are semi-evergreen, resembling someone the small, needle-like foliage of some conifers. The foliage is dense and glossy green, lacking leaf stalks.

Individual leaves are linear and less than an inch in length. They have smooth margins and are rigid, creating a prickly texture.

Small, white hairs may be seen along the edges of the leaf.¹⁷

Identifying Creeping Phlox Seeds

As the Moss Phlox flowers begin to die out in early summer, they are supplanted by small, oval-shaped capsules that contain the Creeping Phlox seeds. Each capsule is less than ¼ of an inch long.

The capsules are divided into three compartments, each of which contains small seeds. Creeping Phlox reseeds itself when the capsules dry out and dehisce, dispersing the seed.¹⁷

Creeping Phlox Colors (Popular Cultivars and Varieties)

There are many cultivars of Phlox subulata, further enhancing the natural diversity of Creeping Phlox colors. Many of the cultivars have petals with more dramatic lines and shapes and some have multi-colored corollas. There is a variety for every garden and every gardener.

“Blue Creeping Phlox” is a bit of a misnomer, as the flowers of emerald blue Creeping Phlox are more a lavender hue than true blue flowers, but the blue tones can be better appreciated from a distance and at specific times of day.

There are now several cultivars of pink Creeping Phlox, including ‘Emerald Pink,’ ‘Drummond’s Pink,’ and ‘Rose Star Pink.’¹⁶

Certain varieties, such as ‘Purple Beauty’ even have darker centers, adding depth and dimension to an already breathtaking flower.⁵

Creeping Phlox Facts

The herbaceous perennial, Phlox subulata, is a gorgeous flowering plant with a mounding, spreading growth habit. Commonly known as Creeping Phlox or moss phlox, the plant sports dense semi-evergreen foliage with a bounty of beautiful small blossoms in spring.

Some interesting Creeping Phlox facts include:^11,17

• Creeping Phlox is useful in controlling erosion on hillsides.
• In the historical tradition, Creeping Phlox symbolism has represented the ideas of harmony, unity and romantic intimacy.⁸
• Creeping Phlox is more tolerant of dry, hot conditions than many of its close relatives.
• The foliage of Creeping Phlox is beautiful even when no blooms are present.
• Creeping Phlox naturally suppresses weeds.
• P. subulata attracts beneficial insects and pollinators with its bright colors and appealing aroma.
• Moss phlox is cold-tolerant enough to grow in parts of Southern Alaska!

The Creeping Phlox or moss phlox is one of the most well-known species, but there are many other familiar members of the Phlox genus, such as:

• Annual Phlox (Phlox drummondii)²⁷
• Downy Phlox (Phlox pilosa)²⁸
• Garden Phlox (Phlox paniculata)²⁹
• Marsh Phlox (Phlox glaberrima) ³⁰
• Meadow Phlox (Phlox maculata)³¹
• Woodland Phlox (Phlox divaricata)³²

What Is Mountain Phlox?

‘Mountain phlox’ is a common name often applied to various species in the Phlox genus. Though it is sometimes used to refer to Creeping Phlox, Phlox subulata, it can also indicate the perennial variety native to the Southwestern United States: Phlox austromontana.^4,13

What Is Carpet Phlox?

Phlox subulata and other low-growing Phlox species, such as Phlox stolonifera (also known as Creeping Phlox), are sometimes called carpet phlox due to their tendency to form dense, mat-like mounds that ‘carpet’ the ground. Some varieties are even resilient enough to tolerate gentle foot traffic.¹⁵

Benefits of Growing Creeping Phlox Ground Cover

There are many advantages to growing a Creeping Phlox ground cover. Not only is Creeping Phlox beautiful and fragrant, but it is also a very tolerant plant! Here are some other reasons to plant phlox as a ground cover:¹⁸

• Creeping Phlox attracts lots of pollinators, including various types of butterflies and types of bees!
• Phlox subulata can grow in sandy, rocky terrain and can combat the effects of erosion.
• Moss phlox can survive prolonged periods of intense cold and frosts.
• The plant is extremely low maintenance and rarely needs any care once established.
• Creeping Phlox can be treaded on lightly without sustaining permanent damage.
• P. subulata naturally suppresses weeds with its dense mat-like form.
• It is a native plant that is suitable for growing in the U.S.

Versatile, hardy, and colorful, Creeping Phlox is a favorite in any garden for both its beauty and it’s utility.

Frequently Asked Questions About Creeping Phlox