Ornamental · Mazaceae
Creeping Mazus
Mazus reptans
A low, moisture-loving carpet that knits between pavers and breaks into purple-blue bloom each summer.
Full sun
Every 3–7 days
USDA 5–8
1–3 in · 3–8 cm
Overview
Creeping mazus is a low, fast-spreading groundcover that forms a dense green mat just 1 to 3 inches (3 to 8 cm) tall. It belongs to the family Mazaceae, and its rooting stems creep outward and grab hold at every node, so a few plants fill a space quickly. People reach for it as a lawn alternative and as a soft filler between stepping stones, where it takes light foot traffic in stride.
The payoff comes in early summer, when the mat throws up small, two-lipped flowers shaped like little snapdragons. Most plants bloom purplish-blue with white and yellow throats, while the 'Albus' form blooms clean white. Unlike many groundcovers that bake in dry sun, mazus wants steady moisture and rich ground, and it rewards that with thicker cover and more flower.
It earns its keep with almost no fuss, but the same vigor that fills a bed will carry it into a lawn if you let it. In some northern states it's treated as an invasive weed, so give it edges or a contained spot. Plant it where you want a green carpet, not where you need a tidy line.
Care
The short version: full sun to part shade, soil kept consistently moist and never bone dry, and a contained spot or an edge so it doesn't wander into the lawn.
Light
Mazus grows in full sun to partial shade, and it flowers best with several hours of sun. Where summers turn hot and dry, give it the afternoon shade instead, which eases the heat stress that browns the mat.
Water
This is the one thing mazus is fussy about. Keep the soil consistently moist and don't let it dry out, especially in hot weather, since it wants more water than most groundcovers. Aim to water every 3 to 7 days, and more in a heat wave.
Soil
Plant it in moist, humus-rich, well-drained soil. It isn't picky about texture and takes clay, loam, or sandy ground, along with medium to wet sites, and it handles a wide pH range from 5.5 to 7.5.
Temperature
Hardy through USDA zones 5 to 8, mazus shrugs off cold down to about -20°F (-29°C) and takes summer heat to roughly 86°F (30°C). In the coldest part of that range, expect some winter dieback.
Humidity
Ordinary outdoor humidity suits it, so there's no level to chase. What matters more is soil moisture and airflow, since a soggy, stagnant spot invites slugs.
Feeding
Mazus rarely needs feeding. If growth looks weak, a light spring topdressing of compost or balanced fertilizer is plenty, and most plantings do fine with nothing at all.
Pruning
Upkeep is minimal. An occasional mow or trim neatens the mat and it tolerates light foot traffic, but the real work is edging it back so it doesn't creep into lawns and beds.
Repotting
not applicable as an in-ground groundcover
Size & spacing
Each plant stays low, just 1 to 3 inches (3 to 8 cm) tall, and spreads 6 to 12 inches (15 to 30 cm) wide. Space plants so the runners can knit into one continuous mat over a season.
When to plant
Mazus is a hardy perennial for zones 5 to 8. Set plants out in spring once the last frost has passed, and they'll knit together over the season and 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 an easy plant, and most of its trouble comes down to too little water or too much vigor. Read the early signs in the mat and you can step in before a small patch turns into a bare one. Match what you see below, then act.
The mat scorches and thins out in summer heat
This is drought stress, and mazus shows it sooner than tougher groundcovers because it wants steady moisture. The mat browns and turns patchy once the soil dries out, especially in full afternoon sun. Water deeply, mulch lightly to hold moisture, and move it into part shade if your summers run hot.
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
It creeps past its bounds into lawn and beds
Mazus spreads by rooting stems that grab hold at every node, and in rich, moist ground it moves fast. Left alone it slips into turf and neighboring plantings, and in some northern states it is treated as an invasive weed. Edge the bed, pull or mow back the runners, or simply plant it where you want it to roam, such as between pavers.
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
Bare patches after a hard winter
At the cold edge of its range, mazus is only semi-evergreen to deciduous and can thin or die back after a severe winter. This shows up most in the coldest part of zones 5 to 8 and in marginal sites. Lay a light winter mulch for protection, give it a sheltered, well-drained spot, and fill any thin patches in spring.
Fix:
- Apply a light winter mulch in marginal zones for protection
- Replant thinned areas in spring
- Grow in a sheltered, well-drained spot
Ragged holes in the leaves with silvery trails
Damp, shady ground is exactly what slugs like, and they leave irregular holes and slime trails behind. The damage is cosmetic and worst after wet weather. Hand-pick them at dusk, ease off on moisture where you can, and scatter iron-phosphate bait if they get out of hand. Beyond slugs, mazus has almost no serious 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
Good news for households with animals: creeping mazus is not listed as toxic and is safe to grow around pets, livestock, and children. A pet that nibbles a mouthful of foliage might get a brief, mild stomach upset at worst. No special handling is needed.
Safe for
People · Cats · Dogs · Horses · Rabbits · Livestock · Birds
Cats Safe
Mazus isn't on the ASPCA toxic list, so a curious cat can nibble the foliage without harm. A big mouthful might cause a brief stomach upset, nothing more.
Dogs Safe
Safe for dogs to brush past or sample. The most you'd see from a real binge on the leaves is some passing, self-limiting tummy trouble.
Horses Safe
No toxins of concern for horses, and a grazing horse can step on or crop the mat without worry.
Rabbits Safe
Rabbits can graze the leaves freely. There's nothing poisonous in the plant for them.
Livestock Safe
Cattle, goats, and sheep can graze it without trouble, since the foliage carries no known toxic compounds.
Birds Safe
Backyard hens and other birds can peck at the plant safely, with no toxic parts to avoid.
People Safe
Handling and weeding mazus poses no risk, and it's not known to irritate skin. It isn't grown to eat, so there's no reason to make a meal of it.
Not poisonous; pets that nibble foliage may at most have mild, temporary stomach upset.
Varieties
Mazus comes in just a couple of forms, set apart mainly by flower color. Both grow and spread the same way.
Species form (purple/blue)
The everyday form carries small, two-lipped, snapdragon-like flowers in purplish-blue, each throat splashed with white and yellow.
'Albus'
A white-flowered selection that matches the species in every way but the color of its blooms.
How to propagate
Multiplying mazus takes almost no effort, since the plant is already spreading and rooting on its own. You can speed it along by lifting and splitting the mat.
DivisionEasy
Spring · A few weeks to a season
The simplest way to make more is to dig up the rooted mat in spring and pull it into pieces. Each chunk already has roots, so it takes hold again within a few weeks and fills in over the season.
LayeringEasy
Spring to summer · A few weeks
Mazus does much of this work for you. From spring through summer its creeping stems root on their own wherever a node touches the ground, and you can lift those rooted sections in a few weeks and move them where you want.
Myths
Mazus is just creeping thyme under another name.
It's a separate plant in the family Mazaceae, not a thyme at all. Creeping thyme wants dry ground and hot sun, while mazus needs steady moisture and rich soil. Mazus also gives you small snapdragon-like flowers in purple-blue or white with spotted throats, which thyme never does.