Ultimate Guide to Growing Creeping Phlox

Creeping phlox (Phlox stolonifera) is an attractive, low growing mat like plant. Ideal for providing ground cover, creeping phlox can also be used in rock gardens or planted in wall and paving crevices. These striking ornamental plants look particularly effective tumbling over the sides of stone walls and pots.

Flowering from late spring until early summer the plants’ are covered in a carpet of small, five petal flowers. Available in a range of colors, the blooms bring both color and fragrance to the garden. They also attract scores of pollinators such as butterflies. After flowering has finished for the year the needle-like foliage remains, continuing to provide masses of green interest and ground cover. While creeping phlox is classed as a herbaceous perennial, the foliage can die back during cold winter spells.

Elegant and attractive, this is a reliable addition to the garden.

Also known as star rock or moss phlox (P. Subulata) the plant can achieve a spread of between 9 and 18 inches. Depending on the variety it can grow to a height of between 6 and 12 inches.

If you want to add creeping phlox to your garden, this is everything you need to know.

Different Varieties of Creeping Phlox

Part of the larger phlox genus, there are a range of different varieties available. The vast majority share the same growing needs and preferences. However some cultivars, particularly those belonging to the moss genus (P. Subulata) are less shade tolerant than others.

Two of the most common varieties are Blue Ridge and Pink Ridge. Attractive, colorful plants they are named after the Appalachian Mountain ranges from which they originate. Another striking cultivar is the white flowering Bruce’s White. Similarly, Snowflake fills spaces with masses of delicate, white blooms. If you want to add a little color to your garden, Sherwood Purple provides a carpet of purple-blue flowers.

For something a little different, Candy Stripe is a pink, vibrant striped variety. Home Fires is another eye catching, pink variety. Finally, Emerald Blue provides a mass of lilac-blue flowers. It is ideal for creating a waterfall effect in your garden.

Take the time to explore all the different varieties and colors available.

You can grow creeping phlox from seed, but this is a slow process. Compared to other specimens, these plants require careful nurture for a number of seasons before they can be planted out. A quicker method is to purchase young or small plants from a garden store or plant nursery.

Growing from Seed

Sow seeds undercover about 2 months before the last frost date. This gives the seeds plenty of growing time before planting out in the spring.

Sow the seeds in trays filled with a well draining potting medium. An even mixture of perlite and coarse sand is ideal. Moisten the mixture before sowing. Sow seeds as thinly as possible before covering with a light layer of the potting medium.

Place the tray in a light position, ideally the seeds should receive around 12 hours of light a day. If you struggle to find a light enough position, you can place the trays under a grow light. Keep the soil evenly moist, not soggy, until the seeds germinate.

While growing from seed is possible it can take a long time. Instead you can purchase young plants or start from cuttings and divisions. 

Following germination, allow the seedlings to grow on in their light position. When they are large enough to handle, transplant the seedlings into small, individual pots.

Be warned, growing from seed is a slow process. Continue growing the seedlings on in pots until they are large enough to cope when planted in the ground. This can take up to 2 years in some cases.

Where to Plant

Most varieties of creeping phlox are hardy in USDA Zones 5 to 9. Some varieties can tolerate cooler conditions.

The plants do best in full sun positions. While they also grow in partial sun positions, flowering may not be as profuse. Avoid planting in overly shady positions. This slows growth and deters flowering.

The creeping phlox plant thrives in a loamy, well draining soil. Planting on a slope helps to promote drainage. Planting in this way also helps to combat soil erosion.

For the best results the soil should also be rich in organic matter. This can be worked in before planting. Finally, the soil should be slightly acidic. However the plants can also tolerate a neutral soil. If your soil is very alkaline, there are a number of ways to make it more acidic.

For the best results, plant in a light position in rich soil. 

Creeping phlox tolerates heat well. Pleasingly the plants can also endure temperatures below 40 ℉. However, the foliage may suffer some cold weather damage, particularly if the plants are exposed to cold weather for a prolonged period. If you are growing in a colder zone, cover the plants in the fall with a horticultural fleece. The Agribon Floating Frost Blanket provides plants with protection from cold weather. This is a permeable solution meaning that while the plants are insulated, light and moisture can still them. Remember to remove the cover in the spring, as temperatures warm.

Humidity is rarely an issue for these plants.

How to Plant Creeping Phlox

This is an easy going plant. Work in organic matter, such as compost, or other amendments before planting to enrich the soil.

To plant, make a hole in the soil large enough to comfortably hold the plant’s root ball. The hole shouldn’t be too deep. When placed in the hole the plant should sit either at soil level or slightly above the level of the soil. Don’t bury the stem too deeply in the earth.

After positioning the plant, start to gently backfill the hole. Be careful not to sink the plant. Water well. Continue to water regularly, keeping the soil evenly moist, until the plant is established in its new position and new growth is visible.

Space your creeping phlox plants 15 to 18 inches apart. This gives them plenty of room to spread, or creep, and establish their leggy runners. Planting in staggered rows allows the plants to thrive without impeding each other’s growth.

Planting in Pots

A versatile plant, creeping phlox also thrives in container gardens.

To plant, fill a clean container with good quality potting soil. It should also have at least one drainage hole in the bottom. Work in a small amount of all-purpose fertilizer if your soil mix doesn’t already contain any. Plant as described above. Be careful not to overcrowd the plants, allow around 6 inches of space between each plant. This gives them plenty of room to spread and grow.

Caring for Creeping Phlox

Once established, creeping phlox is a pleasingly low maintenance plant. As it grows and begins to spread, keep the area around the plant weed free. There are a number of weeding tools that can help you achieve this.

A low maintenance plant, creeping phlox needs little encouragement to produce masses of foliage and flowers. 

When to Water

After the plant is established you only need to water it during prolonged dry spells. Water once a week during dry spells.

While only moderate amounts of moisture are required, you can also give the plants a little extra water if the weather is warm. A soil moisture meter, such as the Gouevn Soil Moisture Meter, is a great investment if you struggle to know when to water your plants.

How to Fertilize

Once a year, either in late winter or early spring, apply a slow release general purpose fertilizer suitable for flowering plants. This promotes growth and robust flowering over a prolonged period.

Pruning your Plant

Whether you prune or not depends on how neat you want to keep the plant. After flowering has finished for the year you can trim back the foliage, to tidy up the appearance of the plant. This also helps to encourage more, dense foliage to form. While this is particularly useful if you are planting for groundcover it is not strictly necessary.

While some growers don’t deadhead the spent blooms others do, believing that it helps to encourage a second flowering.

Older plants can sometimes become woody. Use a garden scissors to prune away any older stems that lack foliage and flowers to help rejuvenate the plant.

How to Propagate Creeping Phlox

While you can grow from seed this is a slow process that can take a number of years before you have a healthy and productive plant. Instead creeping phlox is easily propagated either by division or by taking cuttings.

Dividing the Plant

You can divide the plant as soon as flowering has finished for the year. However, this method of propagation is best done in the fall when temperatures are cooler.

To divide the plant, carefully dig up the entire plant and root ball. You may need to completely encircle the plant a few times, digging deeply before using a shovel to lift the entire plant.

After lifting, gently brush any remaining soil from the roots and inspect for damage. Use a shovel or garden scissors to cut the roots, dividing the plant in half. Large plants can be divided into 3 or 4 healthy sized sections. Replant as described above.

Creeping phlox plants can be divided once every 2 to 3 years without causing it too much damage.

How to Take Cuttings

You can also propagate creeping phlox by taking stem cuttings either in the summer or the fall. Many gardeners prefer to take their cuttings in the fall, believing that the stems tend to take better after flowering.

Source: https://www.youtube.com/watch?v=HjTvA6YL1tU 

Take cuttings from healthy rooted stems or lateral shoots near the tip. The cutting should be about 6 inches long. While there should be at least one set of leaves on your cutting there should not be any flowers.

Remove foliage from the lower half of the cutting. Dip the cut end in a plant rooting hormone before planting in a soilless medium. Creeping phlox roots easily so there is no need to use a rooting hormone, however it can help to encourage the process.

Plant in a pot filled with a well draining or soilless potting medium. An even mixture of perlite and coarse sand is ideal. Place in a light position and keep the soil moist. Roots should form within 6 to 8 weeks. Once roots have formed, harden off the cutting before planting out.

Common Pests and Problems

An easy to care for plant, creeping phlox rarely suffers from any major problems. It is also deer resistant.

This cultivar is less susceptible to powdery mildew than other types of phlox. Correctly spacing out the plants, so that air can freely circulate, and pruning away old and entangled branches can further help to prevent this issue.

Spider mites can be a problem. Particularly if the plants are growing in a hot and dry position. Should you notice any signs of infestation, treat the foliage with an application of homemade insecticidal soap. Pests can also be washed away with a blast from a garden hose.

Foliar nematodes can be problematic during wet or humid spells. Keeping the ground as clear and weed free as possible can help to prevent the issue. Foliar nematodes are tiny pests that can cause lesions to appear on foliage which turn brown and then black. Infestation can be difficult to spot until they are well established. This makes it a difficult problem to control or cure. If an infestation does occur, dig up and destroy the affected plant. Do not place it on the compost heap.

A colorful groundcover option, these plants are a great, low maintenance way to fill your garden with colorful flowers. 

Flowering profusely for 3 to 4 weeks from mid spring onwards, the fragrant, colorful creeping phlox is an attractive addition to any garden. A low maintenance foundation plant that thrives in rock gardens, pots and as ground cover. Creeping phlox is a versatile plant that suits a range of different planting schemes and situations. It is also a popular combination plant, looking particularly effective alongside carnations and euphorbia. Alternatively plant a mass of creeping phlox plants to create a colorful, floral spring blanket.

Colorful, fragrant and popular with pollinators the versatility of creeping phlox means that it works in almost any garden. Why not add one to your garden today?