Hardy Ice Plant

Aubrieta (Aubrieta deltoidea) is a low, mat-forming evergreen perennial in the mustard family (Brassicaceae), native to the rocky hillsides of southeastern Europe - primarily Greece, the Aegean Islands, Crete, and adjacent Mediterranean coasts. It is one of the most reliable spring-flowering ground covers for sunny, well-drained spots: cascading sheets of violet to deep pink four-petalled blooms from March through May, attractive to bees and bee flies. The honest catch is that without a hard cut-back immediately after flowering, plants become woody and bare in the centre within two or three years, collapsing from a tight carpet into a tired, gappy mat.

Felicia amelloides is an evergreen, woody-based perennial subshrub native to a narrow coastal strip of South Africa's Western and Eastern Cape, where it colonises stabilising sand dunes, sandy flats, and rocky outcrops at 0 to 3,280.8 feet. In the garden it delivers a near-continuous flush of sky-blue, yellow-centred daisy flowers on neat mounding growth, typically 12 to 24 inches but capable of reaching about 3.3 feet, making it one of the few true blue-flowered plants for sunny pots and borders. The honest catch is frost-tenderness: it survives only light frost in sharply drained soil and collapses below about 23°F, so outside USDA zones 9-11 it must be overwintered under glass or replaced annually - a real commitment in cool-temperate gardens.

Campanula carpatica is a low, mounding herbaceous perennial native to the rocky subalpine habitats of the Carpathian Mountains, ranging across Poland, the Czech Republic, Slovakia, Romania, and Ukraine (Wikipedia). Its wide, upward-facing bell flowers in violet-blue, white, or pink appear from June through August, making it one of the longest-blooming edging perennials available, and it holds an RHS Award of Garden Merit. The honest catch is longevity: it tends to behave as a short-lived perennial, often thinning or declining after a few seasons, so gardeners should plan for regular division or fresh plants from seed to hold the planting.

Cheddar pink is a low, mat-forming evergreen perennial pink (a Dianthus, not a true carnation) native to calcareous rock ledges and cliff faces across western and central Europe, from the protected population at Cheddar Gorge in England east to Ukraine. Its intensely clove-scented, fringed rose-pink flowers and blue-grey foliage make it one of the finest front-of-border edging plants in a sunny, sharply drained garden. The honest catch is drainage: in any soil that holds winter moisture the crown rots reliably, so it fails in heavy clay or irrigated beds and thrives only where drainage is sharp and the site stays dry underfoot in cold months.

Chionodoxa forbesii (syn. Scilla forbesii) is a small bulbous perennial native to western Turkey - botanically recorded only from Babadağ Mountain in Muğla Province - producing loose racemes of up to 12 star-shaped, sky-blue flowers with white centers on 4 to 6 inches stems in early to mid-spring. It naturalises freely under deciduous trees and in lawns, filling gaps with carpets of colour before most other plants wake from winter, which is its genuine garden gift. The honest catch is its eagerness to spread: it seeds prolifically and the bulbs multiply quickly, so in a small garden or a formal bed it can crowd out neighbours and become hard to contain once established. All parts are toxic if eaten, and the bulbs need a dry summer dormancy or they rot.

Sea thrift is a compact, evergreen, clump-forming perennial native to coastal cliffs, salt marshes, and mountain rocks across the circumpolar Northern Hemisphere - from the British Isles and Scandinavia to the Azores, Greenland, and the Pacific coast of North America. In the garden it is prized for its tight grass-like mounds and globe-shaped, deep-pink to lavender flower heads on wiry stems from spring through midsummer, making it indispensable for rock gardens, edging, and seaside plantings. The honest catch is its intolerance of rich, fertile, or waterlogged soils: given good drainage and lean conditions it thrives for years, but in heavy, moist, or overfed beds it rots at the crown and the centre of the clump goes bare within a few seasons, demanding timely division to rescue it.