Even though many perennial ground covers are hardy and can survive winter's minimum temperatures, their appearances during winter can vary widely. To determine which ground cover species and varieties tolerated cold while continuing to look their best, Abbas Shirazi, horticultural researcher at the Morton Arboretum in Lisle, Illinois (zone 5), conducted a survey of winter injury and appearance of 172 ground covers growing at the arboretum. Researchers visually evaluated and scored plants for damage. Scores went from 1 (no damage) to 5 (dead). No winter protection was provided, and minimum temperatures reached -20° F with inconsistent snow cover.
Of the common types of evergreen ground covers, the following showed no winter injury and retained the best appearance. All nine varieties of winter creeper (Euonymus fortunei) and seven varieties of English ivy (Hedera helix) remained virtually unchanged through the winter; exceptions were 'Gold Heart' English ivy and 'Harlequin' winter creeper, which showed minor damage in late winter. Three varieties of Ajuga reptans -- 'Braunherz', 'Catlin's Giant', and ' Gaiety ' -- were the best of eight varieties evaluated. Pachysandra terminalis 'Green Sheen' was the best of five Japanese spurges, and Sedum spurium 'Fuldaglut' proved the best of five stonecrops. Plants are widely available.