Iberis sempervirens is a perennial in the cabbage family with evergreen foliage and a compact, low-growing habit. It produces its main display of flowers from April to June. Plant in well-drained, sandy or loamy soil in full sun or partial shade for best performance. It suits south-facing spots and is classed H5, so it is hardy in UK conditions.

Perennial candytuft (Iberis sempervirens) is an evergreen perennial that flowers April to June and prefers full sun with well-drained, neutral to alkaline.

https://en.wikipedia.org/wiki/Iberis_sempervirens

Iberis, commonly called candytuft, is a genus of flowering plants belonging to the family Brassicaceae. It comprises annuals, evergreen perennials and subshrubs native to the Old World.

Iberis sempervirens

Perennial candytuft | Iberis sempervirens

Iberis sempervirens 'Snowflake' is a spreading, branched evergreen in the Brassicaceae grown for its low, mounding habit and spring flowers. It performs best in full sun on moist but well-drained soils. Plant on south- or west-facing, sheltered sites with alkaline to neutral soils such as chalk, loam or sand. Flowering occurs from April to June.

Iberis sempervirens 'Snowflake' is a spreading evergreen candytuft for sunny, south- or west-facing sites on well-drained alkaline soils, flowering April.