Thunbergia alata is a fast-growing twining vine native to Eastern Africa, producing a continuous succession of flowers in orange, yellow, or white with a distinctive dark purple-brown center. A true perennial only in frost-free climates, it is widely grown as a warm-season annual in temperate regions and works well on trellises, wire supports, container obelisks, and hanging baskets.
The vine twines by wrapping its stems around supports rather than using tendrils or adhesive structures. It thrives in warm, humid conditions and flowers prolifically from late spring until frost in cooler zones, or nearly year-round in the tropics. Self-seeding is generous, and the plant is documented as invasive in Hawaii, parts of Australia, and other warm regions where it escapes cultivation into disturbed habitats. In zones 10–11, deadheading promptly or cutting back after peak flowering periods limits unwanted spread.
Powdery mildew
White or grey powdery coating on leaves — usually starting on older growth in humid conditions or when nights cool.
Improve air circulation by thinning plants. Apply neem oil or potassium bicarbonate spray at first sign. Avoid overhead watering.
Fungal leaf spot
Brown or purplish spots on the leaves, often ringed with a yellow halo, that spread and merge in warm, humid, or wet weather; heavily spotted leaves yellow and drop early.
Pick off spotted leaves and clear fallen debris to remove overwintering spores. Improve air circulation by thinning, and water at the base so foliage dries quickly. If it persists, apply a copper- or sulfur-based fungicide at the first sign.
Root rot
Plants wilt, yellow, and stunt even in moist soil; lower stems and roots turn brown, soft, and mushy and the plant may collapse. Most common in heavy, wet, or poorly drained ground.
Improve drainage and stop overwatering, and never plant too deep. Lift and destroy badly affected plants along with the soil around the roots. Grow in raised or free-draining beds to prevent it returning.