Ornamental · Brassicaceae
Candytuft
Iberis sempervirens
Under full sun and sharp drainage, candytuft buries its dark mat under a sheet of small white spring flowers.
Full sun
Every 7–10 days
USDA 3–8
6–12 in · 15–30 cm
Overview
Candytuft is an evergreen perennial of the cabbage family that lies flat to the ground and flowers in spring. Its stems form a low, woody mat crowded with narrow, dark green leaves that hold their color and firmness right through winter in milder zones. By April the foliage all but disappears beneath a dense sheet of small white flowers that draws the first bees.
Spilling from the edge of a bed, over a wall, or among the stones of a rock garden, the trailing stems flow across hard surfaces and weave into a tight carpet 6 to 12 inches tall. The mat is tough as well as fine-textured, holding through cold to zone 3 and through dry spells once the roots take hold. The one thing the crown will not bear is wet, heavy soil packed around its base.
Up close, the plant rewards little more than sun, fast-draining ground, and a shear once the white heads brown. Given that, a single plant persists for years, broadening into a compact evergreen mound of slim dark leaves that stays handsome long after the last petal drops.
Care
The short version: full sun and fast-draining soil matter most, watering stays sparing once the plant is established, and the slim stems are sheared back by about a third right after the white flowers fade.
Light
Candytuft flowers thickest in full sun, which packs the mat tight and crowds the surface with white heads. In partial shade the leafy cushion opens up and loosens, and the flowers come fewer and thinner.
Water
Once rooted, this is a drought-tolerant plant that wants the soil to dry between drinks. The top half of the soil is left to dry, then watered every 7 to 10 days at most. The fastest way to lose it is soggy soil, which softens and rots the crown.
Soil
Sharp drainage counts above all else. The plant accepts clay, loam, or sand without complaint and leans toward a neutral to alkaline pH of 6.0 to 8.0, but ground that stays wet around the roots is more than it can take.
Temperature
This is a genuinely hardy perennial, holding firm from a bitter -40°F (-40°C) up to about 90°F (32°C). The narrow evergreen leaves carry their green through winter across that whole range with no help.
Humidity
Ordinary garden air suits the foliage, so there is no humidity figure to chase. Air movement is what counts, since still, damp air settling in the dense mat invites mildew onto the leaves.
Feeding
Candytuft is a light feeder that asks for very little. A single dose of slow-release general fertilizer in early spring carries the whole season, and overfeeding only pushes soft, floppy stems.
Pruning
A shear after the white heads fade is what holds the plant's shape. The stems are cut back by about one-third as the flowers brown, which keeps the cushion compact and draws out fresh green growth.
Repotting
Candytuft rarely needs repotting and resents being disturbed. Roots circling the drainage holes or soil that dries almost as fast as it is wetted are the signs that it has outgrown its pot.
Size & spacing
The mat stays low at 6 to 12 inches (15 to 30 cm) tall and spreads to about 12 to 18 inches (30 to 45 cm) across. Set at that interval, air slips between the mounds and the slim leaves dry quickly.
When to plant
Candytuft keeps to the spring calendar. Seed is started indoors in late winter, young plants go out once hard frost has passed or in early fall, and the small white flowers open from April into May, at times carrying into early summer.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Sow: Late winter, about 6-8 weeks before the last spring frost
- Plant: Spring after danger of hard frost has passed, or in early fall
- Harvest: Early to late spring (April to May), sometimes into early summer
Hardiness
USDA hardiness zones: 3–8
Temperature: down to -40°C
Troubleshooting
Candytuft is an easy plant, and nearly every trouble it shows traces to too much water or stale air sitting in the mat. The first signs surface right on the crown and the narrow leaves, so a careful eye catches them before they spread. The symptom below is matched, then handled while it still helps.
Wilting stems above a brown, rotting crown
When the stems go limp and the crown darkens to a soft, brown pulp, the plant has crown and root rot, the one failure that finishes candytuft, and it traces to wet soil rather than any disease a spray can reach. The base turns mushy where the stems meet the soil line, and a light pull lifts the whole plant on roots gone black and slick. The worst plants are removed and destroyed, then grit or a raised bed sharpens the drainage before anything goes back in.
Fix:
- Remove and destroy severely affected plants
- Improve drainage by amending soil with organic matter or planting on a slope or raised bed
- Reduce watering and avoid wetting the crown
Powdery white film or spotting on the leaves
A floury white dusting clinging to the dark leaves marks powdery or downy mildew, while small spots and raised rust pustules point instead to fungal leaf disease. Both take hold where the air hangs still and the narrow leaves stay wet. The blemished foliage is stripped away, the plants are opened to 12 to 18 inches between them, and water is aimed at the base so each leaf dries quickly.
Fix:
- Remove and dispose of affected foliage
- Improve air circulation by spacing plants 12-18 inches apart
- Avoid overhead watering and water at the base
Ragged holes torn through leaves and flowers
Torn, irregular holes punched through the leaves and white flower heads after damp weather are the mark of slugs and snails, with caterpillars chewing alongside them at times. The glistening slime trails and the damage left overnight give the feeders away. They are picked off after dark, baits or traps are set where they help, and the damp mulch and litter that hide them by day are raked clear.
Fix:
- Handpick slugs, snails, or caterpillars
- Use slug baits or traps where appropriate
- Remove debris and mulch that harbors slugs near plants
Toxicity
Reassuring news for homes with animals and children: candytuft is not toxic. The ASPCA does not list it among harmful plants, and the extension and botanical sources agree there are no poisoning concerns. A nibbled leaf or a trampled patch does no harm, so it takes a safe place in any family garden.
Safe for
People · Cats · Dogs · Horses · Rabbits · Livestock · Birds
Cats None
A cat that bites into the narrow dark leaves has nothing to fear, since candytuft sits off the ASPCA toxic list.
Dogs None
A dog can nose through and chew the low mat of foliage with no risk of poisoning at all.
Horses Safe
Horses cropping the green stems and leaves are in no danger, as the plant holds nothing known to harm them.
Rabbits Safe
Rabbits can nibble the slim leaves of the groundcover freely, with no toxic part among them.
Livestock Safe
Cattle, goats, and sheep face no poisoning if they reach the leafy mat in the garden.
Birds Safe
Garden birds and backyard poultry can peck through the foliage and flowers without harm.
People Safe
The leaves and flowers are safe to touch and pose no concern around children, though the plant is grown for its bloom rather than for eating.
No special handling precautions are required; routine gardening hygiene such as washing hands after contact is sufficient.
Varieties
Most garden candytuft is sold by cultivar, set apart mainly by size and by the heft of the white bloom. These are the ones worth knowing by name.
Snowflake
A vigorous selection carrying unusually broad leaves and large, tightly packed heads of pure white flowers.
Purity
A compact, free-flowering form that covers itself in sheets of bright white bloom each spring.
Alexander's White
A low, dense mound buried under white flowers, its tidy outline making a crisp edge.
Little Gem
A dwarf reaching only 6 to 8 inches tall, its small stature fitting containers and tight corners.
How to propagate
Candytuft is best multiplied by cuttings or seed, since the single thin main root beneath the mat makes the usual perennial trick of splitting a clump unreliable.
Stem cuttingsEasy
Early to midsummer, right after flowering has finished · A few weeks to root, then transplant once established
Cuttings copy candytuft more surely than any other route. Once the white flowers brown and fade in early to midsummer, leafy pieces about 6 inches long are cut and pushed into a moist, gritty mix of sand or vermiculite, where fine pale roots form within a few weeks and the cutting is ready to lift and move on.
SeedEasy
Sow indoors in late winter or outdoors in spring · Germinates in a couple of weeks; blooms typically the following season
Seed is the easy route, slow only in reaching bloom. Sown indoors in late winter or straight into the soil in spring, the tiny seeds push up small green seedlings within a couple of weeks, though those seedlings hold their first white flowers back until the following season. A few spent heads left to ripen scatter seed and the plant sows itself.
DivisionModerate
Early spring or fall · Several weeks; success is variable
Division is the least dependable way to increase this plant. A clump is lifted in early spring or fall and teased apart so each piece keeps its own roots and firm green stems, yet results stay patchy because the thin main root tears badly when cut. The pieces need several weeks to knit back in.
Myths
Candytuft is easily divided like most spreading perennials.
Beneath the green mat lies a single thin main root on a woody base, so cutting the clump apart often severs that lifeline and the divisions wither. Stem cuttings taken after flowering, or fresh seed, root far more readily into new plants.