Ornamental · Mazaceae
Creeping Mazus
Mazus reptans
A low, moisture-loving carpet of small green leaves that threads between pavers and lifts purple-blue blooms each summer.
Full sun
Every 3–7 days
USDA 5–8
1–3 in · 3–8 cm
Overview
Creeping mazus lays down a low, dense mat of small green leaves that rises only 1 to 3 inches (3 to 8 cm) off the soil. It belongs to the family Mazaceae, and its slender stems creep flat along the ground and press down to root at every node, knitting a few plants into a solid green sheet. That low, leafy cover reads as a lawn alternative and as a soft green seam between stepping stones, firm enough to take light foot traffic.
In early summer the flat green lifts into small, two-lipped flowers cut like miniature snapdragons. Most open purplish-blue with white and yellow throats, the pale streak and yellow blotch catching the eye against the deeper blue, while the 'Albus' form opens clean white. Each bloom sits close over the leaves, so the whole mat seems to color at once, and richer, steadily moist ground brings both fuller foliage and a heavier scatter of flower.
The same low, rooting stems that build that green sheet keep pushing outward and will thread the leaves into a lawn if nothing checks them. Some northern states record it as an invasive weed, so a firm edge or a contained bed holds the green in bounds. It suits a place where a spreading leafy carpet is the aim, not a spot that needs a clean, drawn line.
Care
The short version: full sun to part shade, soil kept steadily moist and never bone dry, and an edge or contained spot so the leafy mat stays out of the lawn.
Light
Mazus grows in full sun to partial shade, and the leafy mat flowers most freely with several hours of sun on it. Where summers turn hot and dry, afternoon shade spares the small leaves the heat stress that would brown them.
Water
Moisture is the one thing the leaves insist on. The soil stays consistently moist and never dries out, especially in hot weather, since mazus drinks more than most groundcovers. Water falls every 3 to 7 days, and more often through a heat wave.
Soil
The roots want moist, humus-rich, well-drained soil. They are not fussy about texture, taking clay, loam, or sandy ground and medium to wet sites, and they hold across a wide pH from 5.5 to 7.5.
Temperature
Hardy through USDA zones 5 to 8, the mat rides out cold to about -20°F (-29°C) and holds its green through summer heat near 86°F (30°C). In the coldest reach of that range, the leaves thin back with some winter dieback.
Humidity
Ordinary outdoor air suits the foliage, so there is no level to hit. What tells on the leaves is soil moisture and airflow, since a soggy, still spot draws slugs to chew them.
Feeding
The mat rarely needs feeding. If the leaves look weak and thin, a light spring topdressing of compost or balanced fertilizer fills them back in, though most plantings green up on nothing at all.
Pruning
Upkeep is minimal. An occasional mow or trim evens the leafy surface and it takes light foot traffic, but the standing job is edging the low stems back from lawns and beds.
Repotting
not applicable as an in-ground groundcover
Size & spacing
Each plant hugs the ground at just 1 to 3 inches (3 to 8 cm) tall and fans its leaves 6 to 12 inches (15 to 30 cm) across. Spacing lets the creeping stems weave their green into one unbroken mat over a season.
When to plant
Mazus is a hardy perennial for zones 5 to 8. Set the plants out in spring once the last frost has passed, and the small leaves knit into a continuous mat over the season, coloring with bloom from roughly June into July.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Plant: spring after the last frost
- Harvest: late spring to early summer (roughly June to July)
Hardiness
USDA hardiness zones: 5–8
Temperature: down to -29°C
Troubleshooting
Mazus is easy, and most of its trouble shows plainly in the mat: too little water or too much reach. The small leaves brown or the low stems thread past their patch before things go far, so reading them early keeps a thin spot from turning bare. Match what the mat shows below, then act.
Green leaves crisping brown and the mat going see-through
When the small leaves crisp at the edges and brown out, and daylight starts showing through the mat, the trouble is drought stress, which mazus wears sooner than tougher groundcovers because it craves steady moisture. The browning bites deepest under a hard afternoon sun once the soil has dried. A deep soaking, a light mulch pressed over the roots, and a move into part shade in hot climates green it up again.
Fix:
- Water deeply and consistently to keep the soil evenly moist
- Site in part shade in hot climates to reduce heat stress
- Mulch lightly around the planting to conserve soil moisture
Low green runners threading out past their patch
The low, leafy runners advance on rooting stems that press down and grip at every node, and in rich, moist ground they lengthen fast. Each node that catches sends the green thread deeper into turf and the beds alongside, and some northern states list it as an invasive weed. A sunk edge, a pull or mow of the loose stems, or a paved gap that welcomes the wandering threads keeps it where you want it.
Fix:
- Install edging to contain the planting
- Pull or mow back stems that escape the bounds
- Site it where vigorous spread is desirable, such as between pavers
The green mat going ragged and bare after cold
At the cold edge of its range the mat holds only a semi-evergreen to deciduous cover, so the small leaves brown, drop, and leave ragged bare soil after a severe winter. The gaps open widest in the coldest part of zones 5 to 8 and where the planting stands exposed. A light winter mulch over the crowns, a sheltered and well-drained site, and fresh pieces set into the bare patches in spring rebuild the green.
Fix:
- Apply a light winter mulch in marginal zones for protection
- Replant thinned areas in spring
- Grow in a sheltered, well-drained spot
Ragged bites in the leaves lit by silvery trails
Damp, shaded ground draws slugs, and they rasp irregular bites out of the small leaves and drag glistening silvery trails across the green. The chewing is only skin deep and stands out most after wet weather, when the trails catch the light. Hand-picking at dusk, a drier surface where the site allows, and iron-phosphate bait under heavy pressure clear them off. Past the slugs, the leaves stay largely untouched by pests.
Fix:
- Hand-pick slugs in the evening
- Reduce excess moisture and improve air movement
- Use iron-phosphate slug bait if pressure is heavy
Toxicity
For a home with animals or children, the small green leaves are nothing to fear: creeping mazus is not listed as toxic and is safe around pets, livestock, and family. A pet that bites off a mouthful of foliage might get a brief, mild stomach upset at most. No special handling is needed.
Safe for
People · Cats · Dogs · Horses · Rabbits · Livestock · Birds
Cats Safe
Mazus is absent from the ASPCA toxic list, so a cat can bite into the small green leaves without harm. A large mouthful might bring a brief stomach upset, and no more.
Dogs Safe
A dog can nose through the low mat or crop a few leaves in safety. Even a full mouthful of the soft foliage leads only to some passing, self-limiting stomach trouble.
Horses Safe
The leaves and stems hold no toxins that trouble a horse, so one can crop the low mat or press it flat underfoot without harm.
Rabbits Safe
Rabbits can graze the tender green leaves freely, since nothing in the plant is poisonous to them.
Livestock Safe
Cattle, goats, and sheep can crop the foliage safely, as the leaves and stems carry no known toxic compounds.
Birds Safe
Backyard hens and other birds can peck at the leaves and low stems safely, with no toxic parts among them.
People Safe
The leaves and stems can be handled and weeded without risk, and the plant is not known to irritate the skin. It is not grown for eating, so no part is meant for the plate.
Not poisonous; pets that nibble foliage may at most have mild, temporary stomach upset.
Varieties
Mazus comes in just a couple of forms, told apart by the color of the same little two-lipped flowers. Both spread on the same low, leafy mat.
Species form (purple/blue)
The species form opens small, two-lipped blooms like miniature snapdragons in purplish-blue, each open throat streaked with white and blotched yellow.
'Albus'
'Albus' carries the same little two-lipped flowers on the same low mat, but in a clean, throatless-looking white rather than purple-blue.
How to propagate
Making more mazus asks almost nothing, since the low stems are already rooting into fresh green as they creep. Lifting and splitting the leafy mat simply speeds that along.
DivisionEasy
Spring · A few weeks to a season
The rooted green mat lifts cleanly in spring and pulls apart into fistfuls of leaf and root. Because each torn piece trails its own white roots, it grips the soil again within a few weeks and closes into fresh green over the season.
LayeringEasy
Spring to summer · A few weeks
The plant layers itself along every runner. From spring into summer the low creeping stems press down and strike root wherever a leafy node meets the soil, and those already-rooted lengths lift free after a few weeks to be set wherever more green is wanted.
Myths
Mazus is just creeping thyme under another name.
Set side by side they are plainly separate plants, and mazus sits in the family Mazaceae, not among the thymes. Where thyme keeps to dry, sun-baked ground, mazus needs steady moisture and rich soil. Mazus also lifts small snapdragon-like flowers in purple-blue or white, each with a spotted throat, blooms the fine-leaved thyme never forms.