Impatiens are popular annual flowers, cherished for their vibrant blooms in shady garden spaces. These plants, often called “busy lizzies,” are native to tropical and subtropical regions. Their origin explains their preference for warmer climates and their distinct sensitivity to cold temperatures.
Critical Temperature for Impatiens Survival
Impatiens are highly susceptible to cold, and specific temperatures can lead to severe damage or death. Generally, impatiens thrive in temperatures between 60°F and 75°F (15°C and 24°C). When temperatures drop below 50°F (10°C), impatiens can begin to show signs of distress.
Temperatures at or below freezing, 32°F (0°C) are fatal for impatiens. Ice crystals form within the plant’s cells. As water inside the plant cells freezes, it expands, puncturing the cell walls and rupturing cellular structures. This internal damage leads to cell death and prevents the plant from transporting water and nutrients effectively once temperatures rise.
A brief exposure to temperatures in the mid-30s Fahrenheit may be survivable for mature, healthy plants, but prolonged exposure below 35°F (2°C) can cause significant damage and lead to death. The delicate, succulent stems and thin leaves of impatiens are particularly vulnerable to freezing, blackening and dying quickly when exposed to such conditions. Even if the air temperature remains slightly above freezing, ground frost can still occur and harm the plants.
Recognizing Cold Stress and Damage
Visual changes in impatiens indicate cold stress or damage. One of the first signs of cold exposure is wilting, where leaves droop and appear lifeless even if the soil is moist. This wilting occurs as cells lose water due to the cold, shrinking and causing the plant to appear limp.
As damage progresses, leaves may develop yellow or brown patches, signaling metabolic struggle. Stems can blacken and become mushy, indicating cell damage and decay. Soft, waterlogged areas on leaves or stems also indicate frostbite. In severe cases, the plant’s growth may slow significantly or stop altogether, and buds might drop before blooming.
Protecting Impatiens from Cold
Proactive measures can protect impatiens from cold. For potted impatiens, the easiest method is to bring them indoors when cold weather is forecasted. Gradual acclimation to indoor conditions is beneficial to prevent shock.
If plants are too heavy to move, or if they are planted directly in the ground, covering them provides a layer of insulation. Use frost cloths, old sheets, or blankets to cover outdoor plants, ensuring the material extends to the ground to trap warmth. Avoid using plastic directly on plants, as it can transfer cold and cause more harm.
Thoroughly watering impatiens before a cold snap helps, as moist soil retains heat better than dry soil, insulating roots. Sheltered planting locations, like near a building or under a canopy, offer natural protection from cold air. While these strategies can extend the life of impatiens, for sustained cold periods, their tropical nature means they are primarily treated as annuals in most climates.