Creeping Phlox (Phlox subulata)

Phlox subulata, most commonly called creeping phlox, makes a stunning addition to any garden or yard. With their spreading nature, you can plant a few creeping phlox plants, provide them with proper care, and then watch, year after year, as the perennial plants slowly take over your yard, creating a carpet of vibrant color. Here, we’ll take you through everything you need to know about growing Phlox subulata flowers at home, including planting, soil considerations, watering, fertilizing, pruning, propagating, and pest control. 

I. Appearance and Characteristics 

Phlox subulata, the creeping phlox, moss phlox, moss pink or mountain phlox, is a species of flowering plant in the family Polemoniaceae, native to eastern and central USA, and widely cultivated.

The odor given off by the plants may be mistaken for that of marijuana.

Growing to about 13 cm (5 in) high at most and covering a 50 cm (20 in) wide area, it is an evergreen perennial forming mats or cushions of hairy, linear leaves. The small, five-petaled flowers bloom in rose, mauve, blue, white, or pink in late spring to early summer. Its habitats include rocky ledges, slopes and clearings.

The plant is cultivated as a front-of-border or groundcover plant. Requiring full sun and well-drained soil, it is very hardy, tolerating temperatures down to −20 °C (−4 °F), and is suitable for hardiness zones USDA 3 to 9. It grows in sandy or gravelly soil.

II. How to Grow and Care

Sunlight

Creeping phlox thrives in bright, direct sunlight. In full sun, these plants will produce the most beautiful flowers.

In particularly hot climates, creeping phlox can still grow beautifully in partial shade that will protect them from the hottest part of the day.

Temperature and Humidity

Creeping phlox does not fare well in high humidity and overly moist conditions. These plants are slightly drought tolerant and prefer low to moderate humidity.

Phlox subulata blooms at average temperatures of about 60°F. These plants enter dormancy between 35°F and 44°F, and they can survive winter temperatures down to -20°F.

Watering

You should water creeping phlox weekly. This plant is capable of surviving a short period without water, so don’t be stressed if you forget about it occasionally. Summers could be tricky because the plant needs more moisture. If the temperatures are high, you could even water it more than once a week. Check if the soil is moist with your finger.

Also, watch out for the changes in the color of the plant. Leaves that are turning yellow indicate your creeping phlox needs your attention. Creeping phlox that is a part of your rock garden might need extra moisture if the weather is hot and dry. The terrain that surrounds the plant could scorch the leaves. These changes in the foliage will be visible right away because the plant will turn dark green or yellow, so you can water it in time.

Soil

Creeping phlox is prone to root rot and fungus in overly moist soil. The best potting soil for Phlox subulata is rich and well-draining soil that contains sand, bark, or perlite.

Creeping phlox thrives in mildly acidic to neutral soil with a pH ranging from 5 to 8.

Fertilizing

Fertilizer gives plants the nutrients they need to grow and create beautiful flower blossoms.

While creeping phlox plants growing in the ground will usually do well without regular fertilizing, you can apply compost or mulch at the end of the season or in early spring to create a more rich environment.

If growing in containers, fertilize in the spring and again in the summer with a balanced, water-soluble fertilizer or mix in slow-release fertilizer pellets at the time of potting.

Planting Instructions

Plant Phlox subulata in spring after the danger of the last frost of winter has passed.

Before planting, scope out a good location for your creeping phlox in your garden. Consider your space and the size of mature Phlox subulata plants before deciding how many plants you will need.

Be sure you have a hand shovel or trowel, slow-release fertilizer pellets or organic compost, and sand or perlite if your soil retains lots of moisture.

If planting in a container, choose one that is well-draining and about 2 to 4 inches larger than your plant.

To plant creeping phlox in the ground, find a spot 1 to 2 feet in diameter and dig a hole that is deep and large enough to accommodate the plant’s entire root ball. When placed in the hole, the top of the root ball should be in line with the top of the ground (or the top of the soil level in a container).

Create an ideal environment for your creeping phlox by ensuring the soil immediately surrounding the plant is well-draining and rich by mixing potting soil, mulch, and sand or perlite. You can also add balanced, slow-release fertilizer pellets to the mixture.

Pruning

Creeping phlox should be pruned and cut back to control growth, maintain shape, and encourage healthy growth the following year.

You can either cut back stems immediately after blossoms are spent to prevent the spreading of seeds or you can wait until the fall. When cutting back creeping phlox in fall, trim back 1/2 the length of the stems or almost to the ground.

This protects the plant during winter and encourages new growth in spring.

Propagation

Creeping phlox is propagated through division. You can divide this plant every two or three years, and the roots will remain healthy. The best time for this is in spring, right after the blooming period. So the first thing you need to do is dig up the root. Use a smaller spade for this and double-check if you got the whole root up.

Then cut it in half as evenly as possible. Place each half back into the ground. Carefully add more soil around the new plants. Remember to water them right after division, and maintain the moisture for about a month after propagation. If your creeping phlox starts growing new stems, you have successfully divided the plant.

Overwintering

To overwinter creeping phlox, prune back the stems in late summer or early fall.

Creeping phlox can survive the winter without any special care in growing zones 4 to 9. If you live in zone 4 or lower, protect your plants’ roots by spreading a layer of mulch over the plants.

Repotting

Creeping phlox growing in a container must be divided and repotted every 2 to 4 years. The best time to do this is in the early spring or fall.

To start, gently tease your plant loose from its container and remove it. Loosen as much soil as you can from the plant’s root ball. If separating, divide the plant into two equal portions. One can return to the original pot, and you can plant the other in another well-draining pot of a similar size.

Pests and Diseases

Signs of Problems:

• Powdery Substance on Plants – This is a sign of mildew fungus growing. It can affect plants that are overly moist or don’t have proper air circulation. Reduce watering frequency. Wash leaves with a solution of baking soda, mild liquid soap, and water.
• Few or No Flowers – Creeping phlox needs at least 6 hours of full sun daily to bloom properly. Mildew can also stunt flowers.
• Drooping Leaves – Usually occurs due to overwatering. Check soil drainage and reduce watering frequency.
• Wilted or Crisp Foliage – This is a sign of not enough moisture. Although creeping phlox is somewhat drought-tolerant, they prefer evenly moist soil. Increase your watering frequency.

Pests and Diseases:

• Spider Mites – The underside of leaves will have a bronzed, yellowed, or speckled appearance. Treat leaves with horticultural oil or spider mite pesticide.
• Phlox Bugs – Curled and yellowed leaves indicate the presence of phlox bugs. Treat plants with horticultural soap or oil and clean up plant debris throughout the year.
• Foliar Nematodes – Signs of these worms include distorted growth and oddly shaped leaves and stems. Treat plants with a specially formulated pesticide solution.

III. Uses and Benefits 

• Medicinal uses

The Mahuna traditionally use creeping phlox as a treatment for rheumatism, although there are no studies into its efficacy.

• Culinary uses

The entire plant can also be brewed to make tea to soothe gastrointestinal issues and make a person calm.

• Ornamental uses

Moreover, one of the greatest advantages of garden phlox is its shallow root system.

This makes it an excellent perennial ground cover for banks and other sloped landscaping, as the roots help prevent soil erosion.

Planting on a sloped surface also creates a wonderful display when in bloom, and it’s common to see mountain phlox planted so it overhangs rock walls dramatically.

The plant is also a great addition to borders, rock gardens, xeriscapes, and along foundations.

Creeping phlox also grows best in partial shade, making it an excellent choice for woodland edges, woodland gardens, cottage gardens, and patio containers.

This plant adds a beautiful splash of color to any place.

Finally, this plant attracts butterflies, encouraging these attractive pollinators to visit your other plants.