Kōkiʻo keʻokeʻo is the native white hibiscus of Hawaii, a small tree of moist valleys and forest edges with a lightly sweet fragrance. The flower is a clean white with a long red-tipped staminal column rising from the center, and each blossom lasts a single day. Several forms occur across the islands, and it is one of the most graceful of the Hawaiian hibiscus for a garden.
Plant it in rich, moist, well-drained soil with morning sun and some afternoon shade. It tolerates full sun if watered, but in hot dry spots it sulks. Prune after a flush of bloom to keep the form open. Aphids, thrips and scale are the usual problems, and a strong spray of water or an insecticidal soap is a gentle first response. Cuttings of semi-ripe wood root in a few weeks.
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.
Phytophthora Root Rot
Wilting despite moist soil, yellowing leaves, stunted growth, and dark, decayed roots and crown tissue. Vines may collapse during hot weather.
Plant in well-draining soil and avoid waterlogging. Remove and destroy affected vines. Improve drainage with raised beds or amended soil and avoid overwatering.
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-Knot Nematode
Swollen galls on roots, poor vigor, wilting in heat, and reduced fruiting. Containers and sandy soils are more prone.
Use clean potting mix in containers. Avoid replanting in infested soil. Maintain plant vigor with mulch and steady watering. Solarize affected garden soil.
Sooty Mold (Scale-Associated)
Black, powdery or crusty coating on upper leaf surfaces and stems. Affected leaves may yellow and drop in severe cases. The mold grows on honeydew secreted by scale insects, mealybugs, or aphids feeding on the plant.
Control the underlying pest infestation first using horticultural oil or neem oil applied thoroughly to stems and leaf undersides. Once pest populations are reduced, sooty mold stops spreading and weathers away over time. Rinse foliage with a strong stream of water to dislodge existing mold deposits.