Iberis saxatilis

rock candytuft

At a Glance

FoliageEvergreen
Height3-6 inches (8-15 cm)
Width8-12 inches (20-30 cm)
Maturity2 years

Growing Zones

USDA Hardiness Zones

4 - 8
These zones indicate the coldest temperatures this plant can typically survive.
What's my zone? →
Frost Tolerancehardy

Overview

Iberis saxatilis is a compact, evergreen subshrub in the Brassicaceae family, growing 3–6 inches (8–15 cm) tall and 8–12 inches (20–30 cm) wide, forming a dense, low mound of dark green, fleshy, linear leaves 0.3–0.75 inch (8–18 mm) long. Stems are woody at the base, becoming herbaceous towards the tips. Flowers are small, white, four-petalled, 0.3 inch (8 mm) across, arranged in dense, flat-topped corymbs 1–1.5 inches (2.5–4 cm) across that nearly obscure the foliage at peak bloom. The outer two petals of each flower are larger than the inner two — a characteristic of the genus Iberis that distinguishes it from other crucifer genera. After flowering, the corymbs elongate slightly as siliculate seed pods develop. Native to rocky, calcareous habitats in the mountains of southern Europe, where it grows on limestone cliffs, scree, and rocky outcrops at 3,000–8,000 feet (900–2,400 m). Among the smallest and most compact of the perennial candytufts — significantly smaller than the commonly grown I. sempervirens. Tolerates drought, heat, and alkaline soil. Does not tolerate waterlogged conditions or heavy clay. Long-lived for a subshrub — plants persist 8–15 years in well-drained sites.

Native Range

Iberis saxatilis is native to the mountains of southern Europe, from the Pyrenees through the Alps, Apennines, and into the Balkan mountains. It occurs on calcareous rock faces, cliff crevices, and scree at elevations of 3,000–8,000 feet (900–2,400 m).

Suggested Uses

Planted in rock gardens, crevice gardens, alpine troughs, and wall tops, spaced 8–10 inches (20–25 cm) apart. Effective as edging along gravel paths and raised beds. The compact evergreen mound provides year-round structure. Tolerates alkaline soil and coastal exposure.

How to Identify

Identified by the very compact, low mound of dark green, fleshy linear leaves and dense white corymbs with asymmetric four-petalled flowers (outer petals larger). Distinguished from I. sempervirens (evergreen candytuft) by the much smaller stature (3–6 inches / 8–15 cm vs 6–12 inches / 15–30 cm), narrower leaves, and tighter cushion habit. Distinguished from Arabis species by the asymmetric petal arrangement.

Appearance

Size & Dimensions

Height3" - 6"
Width/Spread8" - 1'

Reaches mature size in approximately 2 years

Colors

Flower Colors

Foliage Colors

Fall Foliage Colors

Bloom Information

Bloom Period

~4 weeks
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White corymbs open from April through May, covering the mound in a dense layer of flowers. Peak bloom lasts 3–4 weeks. Light rebloom may occur in autumn in the Pacific Northwest if conditions are cool and moist. Pollinated by small bees and flies.

Detailed Descriptions

Foliage Description

Dark green, fleshy

Growing Conditions

Sun Requirements

Requires 6-10 hours of direct sunlight daily
• Full Sun: 6+ hours of direct sunlight
• Partial Shade: 3-6 hours of direct sunlight
• Full Shade: Less than 3 hours of direct sunlight

Soil Requirements

pH Range7.0 - 8.5(Alkaline)
357912
Soil Types
Drainagewell drained

Water & Climate

Water Needs

Very Low

Frost Tolerance

hardy

Time to Maturity

1-2 years

Drought Tolerance

Drought tolerant when established

Care & Maintenance

Care Guide

Plant in full sun in sharply drained, neutral to alkaline, gritty soil with a pH of 7.0–8.5. Space 8–10 inches (20–25 cm) apart. Amend heavy soils with coarse grit and limestone chips. Do not fertilise — lean soil maintains the compact habit. Water sparingly; drought-tolerant once established. Mulch with gravel or stone chips, not organic material. In the Pacific Northwest, site in a raised bed, rock garden, or wall top to ensure winter drainage.

Pruning

Shear lightly after flowering in May, cutting back by one-third to maintain a compact, dense mound and prevent legginess. Do not cut into old bare wood. No other pruning is required.

Pruning Schedule

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summer

Maintenance Level

very low

Container Growing

✓ Suitable for container growing

Minimum container size: 1 gallons

⚠️ Toxicity Warning

Non-toxic