A lush ground cover with cheery spring blooms, creeping phlox, also known as moss phlox, fills in gaps with vibrant colors.
Creeping Phlox (Moss Phlox) Growing Guide
Updated on Sep. 30, 2024
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Creeping Phlox Care
- Botanical name: Phlox stolonifera and Phlox subulata
- Common name(s): Creeping phlox, moss phlox, moss pink, rock pink
- Hardiness zones: 2 to 9, depending on species
- Light needs: full sun to light shade
- Water needs: drought tolerant once established
- Soil needs: well-draining normal to sandy or rocky soil, slightly acidic
- Size: 4 inches to 12 inches tall, 18 inches wide or larger if space permits
- Attracts: butterflies, hummingbirds, bees, hummingbird moths
Fragrant creeping phlox, also known as moss phlox, forms low-growing, dense mats of foliage, covered in star-shaped flowers with exuberant shades of purple, pink, white or blue. As a spring bloomer, it’s particularly helpful for early season bees and butterflies. It also drapes gracefully over retaining walls, pots and baskets.
“Creeping phlox is a stunning flowering perennial for ground cover use,” says Laura Root, a horticulturist at Park Seed. “It’s low-maintenance, adds vibrant color in early spring, fills gaps between stones and attracts pollinators. It also looks great with other spring bloomers, like daffodils and tulips.”
When Does Creeping Phlox Bloom?
Phlox subulata is native to the central and eastern U.S., and Phlox stolonifera is native to the eastern U.S. Subulata typically blooms from March to June, while stolonifera arrives a little later, roughly April to September. Both are cold-hardy, remaining evergreen year-round.
When and Where to Plant Creeping Phlox
Plant both species in the spring or early fall, with enough time to get established before extreme heat or freezes. Both do best in areas with full sun to part shade and are tolerant of poor soils, so long as they’re well-draining.
Another star attribute of this versatile plant is erosion control, especially when mass-planted on slopes. It can tolerate light foot traffic, is resistant to deer, and under the right conditions can spread to create large colonies.
Phlox stolonifera can also tolerate shady spaces, such as under a tree canopy, and does well along a woodland edge or creek bank, says Mary Phillips of the National Wildlife Federation. This species should be planted about 12 inches apart.
“Stolonifera is excellent for woodland or shade gardens,” says Spencer Campbell, Morton Arboretum plant clinic manager. “It’s also useful for covering early spring bulbs and fits well in shaded border fronts or rock gardens.”
Phlox subulata is better suited for dry, sunny spaces with rocky soil. “Its flowers and foliage are best showcased on slopes, rock gardens or as an edge in flower beds,” says Laura. Space this species 18 to 24 inches apart, and water well after planting.
Where to Avoid Growing Creeping Phlox
In southern regions, subulata might benefit from dappled shade, says Hannah Armstrong, a horticulturist at the Lady Bird Johnson Wildflower Center. “They are hearty and waterwise, but think twice about adding them to a garden outside of their native range,” she says. “Instead, look for native alternatives that have evolved over time within the local ecosystem as they will provide more environmental and pollinator benefits in your area.”
Watering and Pruning
Water creeping phlox regularly to help it establish, but avoid overwatering, which can lead to root rot. Apply a balanced, slow-release fertilizer in early spring if needed to boost growth.
After it blooms, trim it back to encourage denser foliage, which will also encourage a brilliant second bloom for subulata in the fall, says Laura. Also, cut dead undergrowth from beneath older plants to help keep them fresh.
Does Creeping Phlox Spread?
You can divide creeping phlox every two to four years (in spring for stolonifera and after blooming for subulata). Water the new plantings regularly until they’re established.
Subulata does not easily reseed, but rather readily spreads through creeping runners. Stolonifera, however, can propagate by seed.
Both species can spread quickly and become weedy under optimal conditions, but neither is considered invasive. “If you don’t want it to spread, you can divide it or effortlessly remove it,” says Laura.
Creeping Phlox Wildlife Benefits
As native plants, both species benefit pollinators and other wildlife by providing food and shelter, plus acting as host plants for several native species of butterfly and moth larvae.
Subulata provides early season nectar for pollinators, and both attract butterflies, hummingbirds, bees and hummingbird moths.
Both are native to the Eastern U.S., with stolonifera especially centric to the Appalachian Mountains, and subulata‘s range extending into the central U.S. and Canada.
Is Creeping Phlox Affected by Pests or Diseases?
Yes. If the soil is too moist, root rot and slugs can become an issue. If it’s too hot and dry, spider mites might settle in. Creeping phlox is also prone to powdery mildew.
“To keep it healthy, ensure good air circulation and deadhead spent flowers to prevent mildew,” says Spencer. “Cutting back stems after flowering also helps prevent mildew and limits self-seeding.”
Because it’s a host to butterfly and moth larvae, you might also notice some damage from caterpillar feeding, but that won’t harm the plant or prevent flowering, says Mary.
Notable Creeping Phlox Cultivars
To find species native to your area, use the National Wildlife Federation’s Native Plant Finder. Hannah recommends checking out ‘Emerald Blue’ or ‘Emerald Pink,’ for their vibrant colors.
Laura likes ‘Candy Stripe.’ The white flowers with pink stripes are popular with hummingbirds and butterflies. It blooms heavily in spring and can repeat in fall. She also suggests ‘Scarlet Flame,’ a quick-growing plant that’s heat and humidity-tolerant.
Spencer’s choices are ‘Pink Ridge,’ ‘Fran’s Purple’ and ‘Sherwood Purple.’ All three are known for thick foliage, robust growth and resistance to powdery mildew.
About the Experts
Laura Root is a horticulturist at Park Seed. She earned her degree in environmental horticulture from Virginia Tech and loves helping gardeners of all experience levels create vibrant, sustainable landscapes.
Spencer Campbell is the arboretum plant clinic manager at The Morton Arboretum in Lisle, Illinois. The Plant Clinic is a free nationwide service providing home gardeners and green professionals with plant and growing advice.
Hannah Armstrong is a horticulturist at the Lady Bird Johnson Wildflower Center. Hannah has a degree in ethnobotany from The Evergreen State College.
Mary Phillips is head of native plant habitat strategy/certifications at the National Wildlife Federation. As an ambassador for nature, she keeps habitat gardening programs flourishing with sustainable practices and ever-evolving scientific knowledge.
