Hibiscus plants (Hibiscus spp.), whether hardy cold-weather varieties or heat-seeking tropical species in U.S. Department of Agriculture cold hardiness zones 5 to 11, can quickly become overgrown without regular maintenance. Not only do neglected hibiscus outgrow their pots, they also accumulate less-than-attractive growth like leggy, weak branches, dead interiors and few flowers. Reinvigorate a struggling hibiscus with a pruning plan, which can improve air and sunlight access throughout the plant, encourage branching and flowering, and reduce pest problems.
Select a pruning strategy. Plan to prune weak, failing plants fully to ground level for a totally fresh start and a larger number of flowers, or take a more conservative approach by thinning out only the long, leggy branches.
Dip a clean rag in 70 percent alcohol and wipe down the blades of the pruning shears to sterilize them.
Take off all dead and diseased wood in the late winter or early spring. Cut close to the branch collar at a 45-degree angle and sterilize the shears between cuts. Prune plants to ground level at this time if desired.
Prune long, weak-looking stems and crossing or crowded stems between February and August. Remove one-half to one-third the branch length, 1/4 inch above an outward-growing node. Make cuts at a 45-degree angle.
Dispose of the trimmed wood in a compost heap or trash bin. Do not compost diseased wood.
Water the hibiscus immediately, and continue its regular watering schedule throughout the season.
Fertilize the hibiscus once each week until new growth appears. Select a water-soluble fertilizer that is low in phosphorus and high in potassium, such as 17-5-24. Use a half-strength ratio of 1/2 tablespoon per gallon of water.