Iberis sempervirens

Iberis sempervirens is an herbaceous, evergreen perennial and a floriferous selection for borders, rock gardens or for use as a groundcover.

Its low-growing, mounding habit complements the small, white, four-petal flowers that appear prolifically each spring. Some cultivars flower in spring and fall. It grows 12 inches tall and 24 inches wide. There are dwarf varieties available. Foliage is glossy and leaves grow to 1 inch long. Flowers will likely mask the foliage completely.

It's hardy in USDA Hardiness Zones 3-9. In the landscape, its foliage needs winter scorch protection in colder climates.

It grows in full sun or part shade, but flowers are more plentiful in full sun. It grows best in well-drained soil.

Plants require a cold period of 40F-45F for one month to flower. After flowering, half of the foliage can be sheared to keep plants tidy.

Crown rot and club root are the primary disease problems, and poorly drained soils are the most common causes of crown rot.

Propagation

I. sempervirens is propagated from seed, softwood cuttings or division, according to Michigan State University Extension.

Softwood cuttings are taken in summer and division is done in the fall. The seed germinates in two-three weeks at 65F-70F, but cultivars may not come true to type.

If sowing 'Snow Cushion,' place trays in a moist, cool (35F-40F) greenhouse for two to three weeks, according to Jelitto Perennial Seeds. Little or no light is needed for germination. 'Snow Cushion' germinates irregularly during a three- to four-week period.

If propagating by division, be careful during transplanting because the stems are somewhat easily unattached from the crown, according to Ohio State's Department of Horticulture.

Some cultivars

'Alexander's White' is a low-growing, early-flowering plant.

'Little Gem' is a dwarf variety that grows 6 inches tall and 15 inches wide.

'October Glory' is an 8-inch-tall cultivar that flowers in fall and spring.

'Snowflake' has a shorter habit than the species.

'Autumn Snow' flowers in spring and fall.

'Purity' has more dense flowers and the growth habit is more compact.

'Snow Cushion' is a dwarf variety that grows 6 inches tall and 10-12 inches wide.

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Specifics

Name: Iberis sempervirens

Common name: Evergreen candytuft.

Hardiness: USDA Hardiness Zones 3-9.

Description: A low-growing, mounded subshrub with floriferous white flowers in spring.
Propagation: Seed, division and softwood cuttings.

Landscape uses: Edging, cascading over walls or groundcover.

For more: Michigan State University Extension, Agriculture Hall, Room 108, Michigan State University, East Lansing, MI 48824-1039; (517) 355-2308; www.msue.msu.edu. Ohio State University, Department of Horticulture and Crop Science, 2021 Koffey Road, Columbus, OH 43210; (614) 292-2001; www.hcs.ohio-state.edu. Jelitto Perennial Seeds, 125 Chenoweth Lane, Louisville, KY 40207; (502) 895-0807; www.jelitto.com.

- Kelli Rodda