Ornamental · Polemoniaceae
Creeping Phlox
Phlox subulata
Give it full sun and sharp drainage, and creeping phlox spreads a spring carpet of color.
Full sun
Every 7–14 days
USDA 3–9
4–6 in · 10–15 cm
Overview
Want spring color without a lot of fuss? Creeping phlox is hard to beat. It's a low, mat-forming perennial that spreads into a thick carpet of needle-like foliage, and then in early to mid spring it practically vanishes under all those flowers. It's happiest on the dry, rocky ground of slopes, walls, and rock gardens, the kind of spots where plenty of other plants just give up.
And it isn't only a one-season wonder. That evergreen mat sticks around through hot summers and rough winters, taking cold all the way down to -40°F (-40°C). Once it's settled in, it really only asks for sun and soil that drains.
Just don't mix it up with garden phlox, the tall summer perennial with the same name. Creeping phlox stays ankle high and creeps outward instead of growing up, and that's exactly what makes it such a handy filler between stones and along the front edge of a border.
Care
The short version: give it full sun and sharp-draining sandy or gravelly soil, and once it's established, water only during long dry spells. Then shear it back by half after the flowers fade to keep the mat nice and dense.
Light
Creeping phlox blooms best in full sun, and while it'll take partial shade, you'll see fewer flowers the shadier it gets. Give it an open, sunny spot and it'll cover itself in color.
Water
Once it's established, it's pretty drought tolerant and only needs water during long dry spells. It likes fast-draining ground and even handles dry, rocky conditions, so just let the top half of the soil dry out between waterings.
Soil
Plant it in sandy or gravelly, humus-rich soil that drains freely, because soggy roots are the one thing it can't stand. A pH from 5.5 to 7.0 keeps it happy, and a slope or raised bed helps the water drain off.
Temperature
This is one tough, cold-hardy plant, handling everything from -40°F to 95°F (-40°C to 35°C). It doesn't need any winter protection across its range, and it comes back like clockwork every spring.
Humidity
Regular outdoor air is all it needs, so there's no humidity level to worry about. What matters way more is good drainage and airflow, since damp, still conditions are what bring on leaf problems.
Feeding
It gets along just fine on lean soil and doesn't ask for much. A light feed of balanced general-purpose fertilizer in spring is all it wants, and feeding it more just gives you soft, floppy stems.
Pruning
Right after the flowers fade, cut the stems back by about half. That one trim keeps the mat dense and compact, stops the center from going woody and bare, and leaves the whole thing looking neat.
Size & spacing
The mat stays low, only about 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'll knit together into one solid carpet.
When to plant
Creeping phlox is all about that spring show, so the year really comes down to planting it and tidying it up at the right time. Pop new plants in during spring or early fall, enjoy the bloom from April into May, and shear the mat back once the flowers are done.
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
Most years creeping phlox barely gives you any trouble, and when it does, you'll see it on the leaves or as a thinning mat. Get familiar with the few signs below and you can jump in early. Find the one that fits, then act while it still makes a difference.
Tiny specks and cobwebby strands on tired leaves
Notice the leaves looking speckled and washed-out with a little webbing tucked underneath? That's usually spider mites, which show up in hot, dry weather and quietly drain the color from the foliage. Blast the plants with a strong spray of water, keep them from drying out, and if the mites won't budge, follow up 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
Bent, blotched leaves when the weather stays soggy
When the weather turns warm and stays wet for a while, foliar nematodes can creep into the leaves and warp them out of shape. The fix is simple: pinch off and toss any damaged foliage as soon as you see it. Water down at the base, give the planting some breathing room, and things usually sort themselves out.
Fix:
- Remove and destroy affected foliage
- Avoid overhead watering and improve drainage
Shoots chewed down low along the mat
Spotting neat little cuts on the stems near the soil? That's almost always rabbits snacking on the mat. A short fence or a repellent sends them packing. They go for new plantings first, so it's smart to cover those early if rabbits are a regular problem in your yard.
Fix:
- Use fencing or repellents to deter rabbits
An empty, twiggy gap where the middle used to be
If the middle of the mat has gone woody and hollow while the edges keep crawling outward, the plant's just overdue for a trim. Shear the stems back by about half right after the flowers fade, and dense new growth fills it right back in. Want to speed things along? Dig up a few of the healthy outer pieces and replant them in the gap.
Fix:
- Shear stems back by about half after bloom to promote dense regrowth
- Divide and replant vigorous outer sections
Toxicity
If you've got pets or grazing animals, here's some good news: creeping phlox is safe all around. The ASPCA lists moss phlox as non-toxic to cats, dogs, and horses, and it doesn't pose any risk to other animals or to people. So plant it anywhere you like.
Safe for
People · Cats · Dogs · Horses · Rabbits · Livestock · Birds
Cats Safe
Cats are totally fine here, since the ASPCA lists moss phlox as non-toxic to them, so a curious nibble is no big deal.
Dogs Safe
Dogs can sniff around and chew the mat all they like, because there's nothing in the plant that'll upset them.
Horses Safe
Got horses nearby? No problem, since creeping phlox isn't poisonous to them at all.
Rabbits Safe
Rabbits love to browse it, and while they'll trim the plant down, it doesn't do them any harm.
Livestock Safe
Cattle, goats, and sheep can graze right around it, because there's nothing toxic to farm animals in there.
Birds Safe
Birds pecking at the flowers or seeds won't run into any trouble with this one.
People Safe
It's harmless to people too, though it's really a plant to look at rather than to eat.
Varieties
There are loads of named cultivars out there, and what mostly sets them apart is flower color and how well they shrug off disease. Here are a few that are worth knowing.
Emerald Blue
A crowd-pleaser thanks to bluish purple flowers that pile up thick over a low, even mat.
Fort Hill
Tough enough to fend off Phytophthora, the root and stem rot that knocks out weaker plants.
White Delight
A clean white-flowered pick that also brushes off southern blight without much fuss.
How to propagate
Making more creeping phlox is genuinely easy, whether you split up an old mat or root a few cuttings from a plant you've already got.
DivisionEasy
Divide in early spring or after flowering. · One growing season
The easiest way to get more plants? Just dig up an established mat and split it in early spring or once the flowers are done. Pull the strong outer chunks away from the worn-out middle, replant them in well-drained soil, and they'll settle in over a single growing season.
Stem cuttingsEasy
Take cuttings in late spring or early summer. · Several weeks to root
Stem cuttings work nicely too, taken in late spring or early summer. Pop them into moist, well-drained media and they'll root on their own in a few weeks, giving you new plants that are spitting images of the parent.
Myths
There's no real difference between creeping phlox and garden phlox.
They've got the same name, sure, but that's about where it ends. Creeping phlox hugs the ground in a mat and blooms in spring, while garden phlox shoots up tall and flowers in summer. They're two different species that behave nothing alike, so it pays to check the label before you buy.
Dogs and cats can get poisoned by nibbling creeping phlox.
Good news if you've got pets: that's just not true. The ASPCA lists moss phlox as non-toxic to dogs, cats, and horses, so a pet that takes a bite of the leaves is in no danger. Go ahead and plant it wherever your animals like to hang out.