Impatiens walleriana is a tender annual grown for continuous bloom in shade and partial shade, where many flowering plants struggle. In Zone 6b it is treated as a warm-season annual, planted after frost and killed by the first fall frost. It fills shaded beds, borders, and containers with steady color from late spring until frost.
It needs consistent moisture and does not tolerate drying out; wilting is rapid but plants usually recover after watering. Plants branch and rebloom without deadheading. Since the 2010s, impatiens downy mildew has caused widespread losses, so monitor for it and choose resistant strains or alternatives if the disease is established in your area.
Impatiens Downy Mildew
Leaves yellow, curl downward, and drop, leaving bare stems. A white, fuzzy coating forms on leaf undersides. Plants may collapse quickly in cool, wet conditions.
No effective home cure once infected. Remove and bag all infected plants, including roots; do not compost. Avoid overhead watering and crowding. Replant resistant impatiens varieties (such as Impatiens hawkeri) or other shade plants, and rotate away from the area, as spores persist in soil.
Botrytis (grey mould)
Grey fuzzy mould on petals and stems, worst in cool wet conditions.
Remove affected parts immediately. Improve air circulation. Avoid overhead watering. Apply copper fungicide if severe.
Spider Mites
Fine stippling or bronzing on leaves, faint webbing on undersides, foliage drying out during hot, dry weather.
Spray foliage with a strong jet of water to dislodge mites. Apply insecticidal soap or horticultural oil to leaf undersides; repeat every 5–7 days as needed.
Aphids
Clusters of small soft insects on new growth and flower buds.
Knock off with a strong jet of water. Ladybirds and lacewings are natural predators. Insecticidal soap as last resort.