You may notice premature flower bud drop on hibiscus and gardenia. This can be caused by insects, as well as cultural or environmental problems. Insects called thrips and midges can damage the unopened bud. Thrips and midges are very small, but you can often see them if you open a bud that has dropped from the plant. Beneficial insects like lady bugs and others can help control these pests.
Temperature and water fluctuations can also cause buds to drop and random leaves to yellow. In addition, too much or not enough fertilizer can stress the plant, resulting in bud drop. Nematodes can parasitize the root system, creating a water and nutritional stress on the plant that also results in bud drop.
Overgrown vines such as wisteria, ivy, flame, coral, honeysuckle and Confederate jasmine can be pruned now. Cut off excess tangled growth. Prune back one-third to one-half and remove rooted suckers that are growing in undesirable areas.
Source: Theresa Badurek, urban horticulture extension agent, UF/IFAS Pinellas County Extension Service. Learn more at askextension.org or pinellascountyextension.org.