Frost Damage
Freezing temperatures (abiotic injury)
Overview
Frost damage occurs when temperatures drop low enough to freeze plant tissues, rupturing cells and disrupting membranes. Tender annuals, blossoms, and soft new growth are most vulnerable. Radiational frosts on clear, still nights can injure plants even when daytime weather seems mild. Cold air drainage into low spots creates frost pockets. In diverse plantings, frost risk is managed with site selection, timing, covers, and choosing plants whose hardiness matches the microclimate.
Symptoms
Leaves and shoots appear water-soaked by morning, then darken, wilt, and turn black or brown as tissues collapse. Flowers and buds freeze and fail to set fruit. Fruit skins may blister or show russeted freeze scars. On woody plants, cambium browning under bark indicates freeze injury to twigs. Damage is often worst at the top of tender plants and on the most exposed side. After a few days, dead tissue dries and may drop, leaving a skeletonized look.
Environmental Conditions
Cool
Prevention
Plant tender crops after the local frost-free date and choose hardy cultivars for shoulder seasons. Site sensitive plants on slopes with good air drainage rather than in frost pockets. Keep thermal mass and windbreaks in mind in permaculture designs. Have floating row cover ready in spring and fall. Mulch overwintering perennials after the ground cools. Track microclimates in your garden over seasons so you learn which beds need cover first.
Management
After a frost, wait to prune until you can see how far live growth resumes; premature cutting can remove tissue that would recover. Water plants the day before a predicted frost if soils are dry, because moist soil holds heat better. Use row covers, cloches, or cold frames for tender crops. Move containers against walls or indoors. Avoid high-nitrogen feeds that push soft growth late in fall on borderline-hardy plants. Harvest ripe fruit before hard freezes.