Evergreen Candytuft (Iberis sempervirens)

Candytuft, Edging Candytuft, Evergreen Candytuft, Garrex's Candytuft, Perennial

Iberis sempervirens plants, commonly known as Evergreen candytufts, Perennial candytufts, or simply Candytufts, are showy species of flowering plants in the Brassicaceae family. Evergreen candytufts are very popular ornamental plants not only due to their abundance of delicate flowers but also for their low-demanding overall nature. Keep reading to find out more about Evergreen candytufts and also learn how to grow, care for, and propagate them like a pro.

I. Appearance and Characteristics 

Iberis sempervirens, the evergreen candytuft or perennial candytuft, is a species of flowering plant in the family Brassicaceae, native to southern Europe. The species is often used as an ornamental garden shrub because of its decorative flowers. Iberis is so named because many members of the genus come from the Iberian Peninsula in south west Europe. Sempervirens means “always green”, referring to the evergreen foliage.

The natural range is in Europe in Spain, France, Italy, Romania and the Balkan Peninsula. In Africa, it is found in Morocco and Algeria. In Asia, it is present in Syria and Turkey. It is naturalized in the British Isles, in Assam, and in North America. It grows in steppes and dry forests on moderately dry to fresh, slightly acidic to alkaline, sandy-loam to loamy, nutrient-rich soils in sunny to light shady locations. The species is heat loving and frost hardy.

It is a spreading subshrub growing to 30 cm (12 in) high by 40 cm (16 in) broad. As an ornamental plant it is a spring-blooming favorite, often seen cascading over rocks and walls, or used as ground cover. The glossy, evergreen foliage forms a billowing mound, with many fragrant, pure white flowers in tight clusters for several weeks during spring and early summer. The leaf blade of the leaves is leathery, 25–75 mm or 1–3 in (and rarely 125 mm or 5 in) long, 2 to 5 millimeters wide, oblong spatulate to lanceolate, obtuse with a pointed base. The fruits are roundish to broad ovate, 6 to 8 millimeters long and 5 to 6 millimeters wide. The seeds are narrowly winged and 2 to 3 millimeters long.

When grown in a garden it may require light pruning right after blooming, but otherwise plants can be left alone in fall and early spring. It is drought-tolerant once established. It prefers a well-drained site, so heavy clay soils that stay wet in winter should be avoided. It is not easily divided. Iberis sempervirens survives in USDA hardiness zones 3–9 with mean annual minimum temperatures of −23 to −21 °C (−10 to −5 °F).

It is hardy in most parts of the UK, surviving temperatures down to −15 °C (5 °F). Vernalization (a period of cold weather) is required for flower initiation. At least 8–10 weeks are needed at an average temperature of 5 °C (40 °F).

The cultivar ‘Snowflake’ has gained the Royal Horticultural Society’s Award of Garden Merit.

II. How to Grow and Care

Sunlight

Candytuft will tolerate some shade but blooms best when planted in the sun. The exception is zones 8 and 9, where it benefits from some shade in the afternoon during the hottest part of the day.

Temperature and Humidity

Candytuft is usually considered hardy in USDA zones 3 to 9, though this has different meanings depending on where you live. It’s evergreen in warm zones, a hardy perennial in cool zones, and borderline annual in the extreme cold of zone 3 unless it’s well mulched for the winter.

The natural environment for candytuft tends to have drier air conditions. For that reason, it’s not recommended for areas with high humidity such as the southeastern United States, as the flowers tend to wilt and fungal diseases are more likely.

Watering

Evergreen candytuft is a self-sufficient plant that doesn’t need much watering except in its first period of growth. After this, it is quite drought-tolerant and only needs additional water in periods of prolonged dry weather. If the soil and the plant look dry, then water deeply.

Soil

Candytuft is native to southern Europe, including areas along the Mediterranean coast; they prefer the kind of gravelly soil found in their land of origin. More importantly, it is critical to provide them with excellent drainage. Because candytuft craves well-drained soils, it is perfect for rock gardens. This perennial prefers to be grown in​ the ground with a soil pH that is on the alkaline side, but it has good tolerance for both slightly acidic and neutral soils.

Fertilizing

Evergreen candytuft does not have excessive feeding requirements and can grow quite well without any added fertilizer. However, to produce the most healthy specimens, it is useful to apply a slow-release N-P-K fertilizer in a ratio such as 5-15-10 at the start of the growing season. When grown in containers this plant should always be fertilized; an all-purpose liquid fertilizer is a better choice than granular fertilizers, and it should be applied according to the manufacturer’s instructions.

Pruning

To keep candytuft looking tidy, prune away the top one-third of the foliage after blooming—this will keep the plant from getting leggy. Some gardeners like to perform deadheading on candytuft with a string trimmer after flowering is complete.3 Without this annual pruning, the plant can become rather scraggly in the border garden.

However, if you are planting candytuft flowers behind a retaining wall, legginess may actually be a good quality. In this case, prune them only if you think the stems are getting too woody-looking. Pruning will spawn new, fresh growth.

Propagation

Stem cuttings

In warmer regions, the plant renews itself through the stems that root themselves around the mother plant. In colder regions, where the plant is more likely to die back to the ground each winter, dividing the roots every few years is the best propagation method. Stem cuttings are not recommended since this method takes some time. Here’s how to divide roots.

  • In fall, just before the plants begin winter dormancy, use a shovel to dig up the entire root clump.
  • Use a sharp knife or garden trowel to divide the clump into two or three pieces. Make sure each section has both stems and a healthy clump of roots.
  • Immediately replant the pieces into their new locations, into soil that has been well loosened and (if necessary) amended to improve its drainage.

Seed

The native species of candytuft can be propagated by seeds collected from the seed pods left behind after the flowers fade. But named cultivars usually do not “come true” from their seeds, so vegetative propagation (see above for root division) is the best method for propagating those varieties.

To grow seeds of the pure species, start them indoors in small containers or direct sow them into the garden in spring after all danger of frost has passed. Take these steps.

  • Sow the seeds about 1 inch deep in well-loosened soil, then water well.
  • Keep the seeds moist until they sprout, and continue regular watering until the plants are well established.
  • Although mature plants can reach up to 18 inches, sow seeds about 6 inches apart to create a ground cover effect more quickly when growing from seed.

Potting and Repotting 

Candytufts can be grown in containers, but rarely are because they aren’t attractive after blooming, they have an unpleasant fragrance, and they take some time to fill a spacious container. If you do want to grow them in pots, choose a fairly spacious, large container with good drainage, and fill it with standard potting soil blended with sand or fine gravel to improve its drainage.

Like any perennial grown in a container, potted candytuft requires somewhat more watering than if it were planted in the ground. Overwinter a potted candytuft plant by moving it to a sheltered location or dig it into the garden up to the lip of the pot for the winter. Because it is slow-growing, it only needs to be repotted every few years.

Overwintering

In regions where the plant performs as a standard perennial and dies back fully in winter, trim off the stems to 3 or 4 inches once frost has killed the leaves.

Some gardeners in cold regions (zones 3, 4) gently place pine boughs over the plants in late fall to shelter them from the cold, drying winds of winter. A 1- to 2-inch layer of standard mulch will have the same effect. In warmer regions, no winter protection is needed.

Pests and Diseases

Common Pests & Plant Diseases

Most insect pests leave candytuft alone, though you may have problems with slugs, snails, and caterpillars, all of which can take some time and various methods to get under control.45

The most common disease issue with candytuft is root rot, which is common when the plant struggles in poorly drained, boggy soil. Badly affected plants should be removed. A variety of fungal diseases are occasional problems, including down mildew, powdery mildew, gray mold, rust, and fungal leaf spots. Rarely fatal, fungal diseases are more likely in humid conditions where air circulation is poor. If the disfiguring appearance is deemed intolerable, these infections can be treated with a fungicidal spray.

Common Problems

Candytuft is generally a fairly trouble-free plant, provided its growing environment is suitable. But you may witness the following problems.

Yellowed Leaves

A candytuft plant that develops yellow leaves is often responding to conditions that are too hot, too wet, or too humid. While you can’t control the temperature, watering in the morning only can help reduce the humidity that can cause yellowing leaves.

Stunted Growth

A plant that seems stunted may be suffering from clubroot, a fungal disease that affects members of the Brassicaceae family, including cabbages. If you dig up a plant with these symptoms, you usually can identify deformed roots. Affected plants must be removed and destroyed.

III. Uses and Benefits 

Evergreen candytuft holds its own in gardens with a lot of sun and well-drained soils. Use it as an edging or border plant, or in a rock garden or raised bed where it can spill over edges and soften harsh geometric lines with its fine textured foliage. Cornflower, Basket-of-gold, or Creeping phlox are colorful companions.

These plants make a great groundcover and also look lovely tumbling over a wall.

Candytuft makes a good choice for a seaside garden as it is tolerant of wind and salt in a sloping substrate.

Additionally, it can resist pollution, drought, deer, and rabbits.

Evergreen Candytuft (Iberis sempervirens) Details

Common name Candytuft, Edging Candytuft, Evergreen Candytuft, Garrex's Candytuft, Perennial
Botanical name Iberis sempervirens
Plant type Ground Cover
Hardiness zone 3a, 3b, 4a, 4b, 5a, 5b, 6a, 6b, 7a, 7b, 8a, 8b
Growth rate Medium
Harvest time Summer
Height 0 ft. 6 in. - 1 ft. 0 in.
Width 0 ft. 6 in. - 1 ft. 0 in.
Sunlight Full sun (6 or more hours of direct sunlight a day)
Soil condition Clay
Flower color Gold/Yellow
Leaf color Green