Ornamental · Polemoniaceae
Creeping Phlox
Phlox subulata
Give it full sun and sharp drainage, and creeping phlox carpets the ground in spring color.
Full sun
Every 7–14 days
USDA 3–9
4–6 in · 10–15 cm
Overview
Few groundcovers put on a show like creeping phlox in spring. This low, mat-forming perennial spreads into a dense carpet of needle-like foliage, then disappears under a sheet of flowers in early to mid spring. It thrives where many plants struggle, taking the dry, rocky ground of slopes, walls, and rock gardens in stride.
It earns its keep all year, not just in bloom. The evergreen mat holds its place through hot summers and bitter winters, shrugging off cold as low as -40°F (-40°C). Once it has settled in, it asks for little more than sun and soil that drains.
Don't confuse it with garden phlox, the tall summer perennial that shares the name. Creeping phlox stays ankle high and creeps outward rather than reaching up, which is exactly what makes it such a good filler between stones and along the front of a border.
Care
The short version: full sun, sharp-draining sandy or gravelly soil, and water only during long dry spells once the plant is established. Shear it back by half after the flowers fade to keep the mat dense.
Light
Creeping phlox flowers best in full sun and will take partial shade, though the bloom thins out the more shade it gets. Give it an open, sunny spot and it covers itself in color.
Water
Once established, the plant is drought tolerant and only needs water during long dry spells. It prefers ground that drains fast and even handles dry, rocky conditions, so let the top half of the soil dry between waterings.
Soil
Plant it in sandy or gravelly, humus-rich soil that drains freely, since wet feet are its main enemy. A pH from 5.5 to 7.0 suits it well, and a slope or raised bed helps the water run off.
Temperature
This is a tough, cold-hardy plant that takes everything from -40°F to 95°F (-40°C to 35°C). It needs no winter protection across its range and comes back reliably each spring.
Humidity
Ordinary outdoor air is fine, so there's no level to chase. Good drainage and airflow matter far more, since damp, stagnant conditions are what invite foliar trouble.
Feeding
It gets by on lean soil and asks for little. A light feed of balanced general-purpose fertilizer in spring is all it wants, and overfeeding only grows soft, floppy stems.
Pruning
Right after the flowers fade, cut the stems back by about half. That one shearing keeps the mat dense and compact, stops the center from going woody and bare, and tidies the whole planting.
Size & spacing
The mat stays low, just 4 to 6 inches (10 to 15 cm) tall, but each plant spreads 24 to 35 inches (60 to 90 cm) wide. Give it that room and it knits together into a solid carpet.
When to plant
Creeping phlox is grown for its spring show, so the calendar centers on getting it planted and then tidied at the right moment. Set new plants out in spring or early fall, enjoy the bloom from April into May, and shear the mat back once the flowers finish.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Sow: Usually propagated vegetatively rather than from seed; not typically sown indoors.
- Plant: Plant in spring or early fall in a sunny, well-drained site.
- Harvest: Blooms in early to mid spring, roughly April to May.
Hardiness
USDA hardiness zones: 3–9
Temperature: down to -40°C
Troubleshooting
Creeping phlox stays trouble-free most years, with problems showing up on the foliage or in a thinning mat. Learn the few signs below and you can step in early. Match what you see, then act while it still helps.
Speckled, fading leaves with fine webbing
Hot, dry spells bring on spider mites, which suck the color out of the foliage and spin thin webs underneath the leaves. Blast the plants with a hard spray of water and keep them from drying out. If the mites hang on, treat with insecticidal soap or horticultural oil.
Fix:
- Spray foliage with a strong jet of water to dislodge mites
- Improve airflow and avoid drought stress
- Treat with insecticidal soap or horticultural oil if needed
Twisted, blotchy leaves during long wet spells
Stretches of warm, soggy weather let foliar nematodes move into the leaf tissue and warp it. Pull off and destroy any damaged foliage the moment you spot it. Water at the base, open the planting up for air, and the problem usually fades.
Fix:
- Remove and destroy affected foliage
- Avoid overhead watering and improve drainage
Foliage clipped and grazed near the ground
Clean-cut stems low to the soil point to rabbits browsing the mat. A short fence or a repellent keeps them off. Young plantings are the most tempting, so guard those first where rabbit pressure runs high.
Fix:
- Use fencing or repellents to deter rabbits
A bare, woody hole opening in the middle of the mat
When the mat goes woody and hollow in the center while the edges keep creeping, it usually means the plant hasn't been cut back. Shear the stems by about half right after the flowers fade to push fresh, dense growth. You can also lift the vigorous outer pieces and replant them to fill the gap.
Fix:
- Shear stems back by about half after bloom to promote dense regrowth
- Divide and replant vigorous outer sections
Toxicity
Good news for pet owners and anyone with grazing animals: creeping phlox is safe all around. The ASPCA lists moss phlox as non-toxic to cats, dogs, and horses, and it poses no risk to other animals or people. You can plant it anywhere without worry.
Safe for
People · Cats · Dogs · Horses · Rabbits · Livestock · Birds
Cats Safe
The ASPCA lists moss phlox as non-toxic to cats, so a curious nibble is nothing to worry about.
Dogs Safe
Dogs can sniff and chew at the mat without harm, since the plant carries no toxin that affects them.
Horses Safe
Horses grazing near a planting face no risk; creeping phlox is not poisonous to them.
Rabbits Safe
Rabbits often browse the foliage, and while that chews the plant down, it does them no harm.
Livestock Safe
Cattle, goats, and sheep can graze around it safely, as the plant holds nothing toxic to farm animals.
Birds Safe
Birds that peck at the flowers or seeds come to no harm from this plant.
People Safe
It poses no danger to people, though the plant is grown for show rather than for eating.
Varieties
Plenty of named cultivars exist, set apart mostly by flower color and how well they resist disease. These few are the ones worth knowing.
Emerald Blue
A favorite for its bluish purple flowers spread thick over a low, even mat.
Fort Hill
Prized for standing up to Phytophthora, the root and stem rot that takes down weaker plants.
White Delight
A clean white-flowered cultivar that also shrugs off southern blight.
How to propagate
Creeping phlox is easy to multiply, whether you split an old mat or root a few cuttings from a plant you already grow.
DivisionEasy
Divide in early spring or after flowering. · One growing season
The simplest way to make more plants is to dig up and split an established mat in early spring or once the flowers fade. Pull the strong outer sections away from the tired center and replant them in well-drained soil, where they settle in over a single growing season.
Stem cuttingsEasy
Take cuttings in late spring or early summer. · Several weeks to root
You can also take stem cuttings in late spring or early summer. Stand them in moist, well-drained media and they root on their own in a few weeks, giving you new plants identical to the parent.
Myths
Creeping phlox and garden phlox are the same plant.
They share a name but not much else. Creeping phlox stays low and mat-forming and blooms in spring, while garden phlox grows tall and upright and flowers in summer. They are two different species with very different habits, so check the label before you buy.
Creeping phlox is poisonous to cats and dogs.
The ASPCA lists moss phlox as non-toxic to dogs, cats, and horses. A pet that nibbles the foliage is in no danger, so you can plant it where animals roam without worry.