Eggplants are warm-season vegetables. Originating from tropical and subtropical regions, these plants are tender and particularly sensitive to cold temperatures. Their vulnerability to frost makes understanding proper care during cooler periods important for gardeners.
Eggplant Sensitivity to Frost
Eggplants are not frost-hardy and are highly susceptible to cold injury. While they can tolerate brief periods of cold, sustained temperatures below their optimal range can cause damage or death. Temperatures at or below 32°F (0°C) can damage eggplant foliage and stems. Even temperatures in the low 40s°F (4-7°C) can stress the plants, leading to stunted growth and reduced fruit production. Their high water content can cause plant tissues to freeze and burst cells.
Signs of Frost Damage
Frost damage on eggplant plants appears as changes in their appearance. Leaves may initially look water-soaked and soft, then quickly turn black or brown. Stems can also darken and become mushy, indicating cell damage from freezing. In severe cases, the entire plant may wilt and collapse. For affected fruit, the skin can develop sunken, water-soaked areas, and the interior may turn brown and spongy upon thawing.
Protecting Eggplants from Frost
Protecting eggplants from frost requires proactive measures. Covering plants with materials such as floating row covers, blankets, or cloches can trap ground heat, providing a protective barrier against cold air. These covers should be draped loosely over the plants and secured to the ground to prevent them from blowing away and to ensure they do not touch the foliage. Watering the soil thoroughly before a frost event can also help, as moist soil retains heat more effectively than dry soil. Container-grown eggplants offer the flexibility of being moved indoors to a warmer location, such as a garage or heated porch, during cold snaps.
Caring for Frost-Damaged Eggplants
After an eggplant plant has experienced frost, assessing the extent of the damage is the first step. Plants with deep frost damage, characterized by translucent, dark leaves and stems, are unlikely to recover. However, if only minor damage, such as blackened leaf edges, is present, the plant might still be salvageable. Prune away any dead or mushy parts of the plant, as these areas can become entry points for diseases. While some plants may show new growth from the stem, severely damaged eggplants often do not rebound and may need to be replaced for a productive harvest.
Harvesting Before Frost
If a frost is expected and your eggplant plants have mature or nearly mature fruits, harvest them beforehand. Frost can damage the fruit itself, causing the skin to develop water-soaked spots and the flesh to become mushy. Harvesting all mature eggplants ensures the existing produce is not lost to the cold.