What to Do After Frost Damage in the Garden

Discovering frost-damaged plants can be disheartening, but don't rush to the compost bin. Many plants that look devastated after a frost can recover significantly, and the right response in the hours and days after a frost event can make the difference between saving a plant and losing it.

Immediately after a frost

The most important thing after a frost is to avoid watering frozen plants with warm water or moving them abruptly into a warm environment. Rapid thawing causes cells to rupture more severely than a slow thaw. If a frost-damaged plant is in a pot, move it to a cool but frost-free location — a garage or unheated porch — and let it thaw slowly. Leave plants in the ground to thaw naturally. In many cases, wilted or blackened leaves thaw out during the morning and recover fully or partially.

Assessing the damage

Wait at least 48 hours after a frost event before making any decisions. Light frost damage affects only the soft tips and outer leaves; the main stems and crown of the plant are often completely unharmed. Symptoms of frost damage include blackened, limp, or water-soaked foliage that turns brown and papery as it dries. Gently scratch the bark of a stem — green beneath the surface indicates the stem is alive. Brown and dry = dead.

• Don't water with warm water immediately after frost.
• Allow a slow, natural thaw.
• Wait 48 hours before assessing damage.
• Scratch stems to check for living tissue.

When to prune frost-damaged growth

Resist the urge to prune frost-damaged growth immediately. The dead material provides some insulation for the living tissue beneath, especially if further frosts are forecast. Wait until the risk of further hard frosts has passed — typically late spring in colder areas — before cutting back. Once frosts are over, remove all dead and damaged material cleanly, cutting back to healthy growth. New shoots often emerge surprisingly low on the stem after hard frosts.

Which plants can recover

Hardy perennials and shrubs with living crowns or roots usually recover well from frost damage, even if all top growth is killed. Tender annuals and bedding plants that are frosted to the roots are usually lost entirely. Borderline-hardy plants like dahlias, cannas, and pelargoniums may survive if the tubers or roots were protected by mulch, even if all the top growth was killed. Check the roots or tubers before discarding — living roots can produce new shoots once temperatures warm.