Sunpatiens are a popular choice for gardeners due to their vibrant, continuous blooms and improved tolerance to sun and heat compared to traditional impatiens. These robust plants offer season-long color, thriving in various garden settings, from beds to containers.
Ideal Growing Temperatures for Sunpatiens
For Sunpatiens to flourish and produce abundant blooms, specific temperature ranges are most favorable. Their comfort zone for thriving spans from approximately 40°F to 95°F (5°C to 35°C). When planting in spring, wait until the soil temperature consistently reaches above 60°F (15°C) for strong root establishment. While they can tolerate cooler nights, temperatures below 58°F (14°C) can slow their growth.
Sunpatiens and Heat Tolerance
Sunpatiens were developed to perform well in warm and humid conditions, demonstrating a notable ability to withstand high temperatures. They commonly exhibit some wilting during the hottest part of the day, particularly mid-day, but typically recover quickly once temperatures cool or after receiving water. Strong, drying winds can also cause stress, leading to faded flowers and moisture loss.
To support Sunpatiens during hot spells, allow the soil to dry slightly between waterings to encourage a stronger root system. Deep watering is recommended, especially for container plants which may need water up to twice a day. Avoiding overhead watering in the morning can prevent “sun scold,” where water droplets on petals magnify sunlight and cause burning.
Sunpatiens and Cold Tolerance
Sunpatiens are sensitive to cold and are generally treated as annuals in most climates because they cannot survive freezing temperatures. Temperatures dropping below 50°F (10°C) can cause them to show signs of distress or damage. A hard frost will quickly blacken their foliage and ultimately kill the plants.
Visible indicators of cold stress include wilted leaves, blackened stems, and mushy spots on the foliage. Prolonged exposure to cold can also lead to chilling injury, fungal problems, and stunted growth. While it is possible to attempt overwintering potted Sunpatiens indoors, they are not naturally suited as houseplants and require a bright, south-facing window with ample light. Bringing them indoors also carries the risk of introducing pests to other indoor plants.
Protecting Sunpatiens from Temperature Extremes
To protect Sunpatiens from adverse temperature conditions, strategic planting and care measures are important. When selecting a planting site, avoid low-lying areas prone to frost pockets. Locations against south-facing walls can provide additional warmth, offering some protection during cooler periods. Planting should always occur after the last frost date, when soil temperatures have warmed sufficiently.
Applying a 4 to 6-inch layer of mulch around the plants can help regulate soil temperature, insulating roots from both heat and cold, and conserving moisture. However, keep mulch a few inches away from plant stems to prevent stem rot. For Sunpatiens grown in containers, moving them indoors or to a sheltered location is an effective strategy when night temperatures consistently fall below 50°F (10°C). Watering plants thoroughly before an anticipated freeze can help, as the water releases latent heat as it freezes, providing some warmth to the roots.