Frosthardy

Frosthardy is a horticultural term used to describe plants that can survive freezing temperatures typical of winter conditions. The term is sometimes written frost-hardy or frost-tolerant; its exact meaning varies by species and local climate, but it generally indicates that a plant can endure subfreezing temperatures without sustaining fatal damage while dormant.

Hardiness is commonly assessed using standardized climate zones, such as the USDA hardiness zones, or local equivalents. A frosthardy species is expected to endure winter lows appropriate to its zone, though extreme weather—rapid temperature drops, desiccation, ice formation, or prolonged cold—can still cause injury. The degree of frost hardiness is influenced by acclimation in autumn, plant physiology, moisture status, wind exposure, and snow cover.

Plant groups often described as frosthardy include many deciduous perennials, evergreen shrubs, and most trees adapted to cold climates. Common examples include hardy grasses, sedums, conifers, and many herbaceous perennials such as echinacea and hostas in colder regions, as well as fruit trees and certain ornamentals. The label is a practical guide for gardeners selecting plants for winter resilience rather than a precise measure of tolerance.

Practically, gardeners can support frosthardy plants by selecting varieties suited to their climate, planting in sheltered sites, incorporating mulch to insulate roots, and protecting with row covers during cold snaps. Avoiding late-season pruning and providing a slow transition into dormancy can also aid hardiness.