Fertilize Hibiscus lightly and often — hibiscus are heavy feeders.
Use fertilizers that include the trace elements such as iron, copper, boron, etc. A dry fertilizer such as a 10-10-10 is all right, however most growers prefer low phosphate fertilizer such as a 7-2-7, feeling that it helps produce the most impressive quality and quantity of blooms.
Those so-called “bloom specials” with the 10-40-10 type of formula are avoided by most professional growers — phosphorous can build up in the soil over time and cause a general decline in the health of tropical hibiscus plants, which is why we here at Slow Release Fertilizers never recommend quick burst ferts.
Over-use of high nitrogen fertilizers may encourage leaf growth rather than flower production. Water soluble fertilizers are good both for spraying leaves (foliar feeding) and for fertilizing potted plants. (High phosphorous water soluble fertilizers can be used successfully when applied as a foliar feeding.)
Experiment and see what works well for your local growing conditions. Slightly acid soil (a pH of 6 to 7) helps the plant absorb nutrients. Hard water and proximity to things like concrete can move the pH in the wrong direction — toward an alkaline pH.
Hibiscus are beautiful flowering plants that need just the right type of plant food. For Hibisucs, my favorite plant food would probably be Dynamite Plant Food (www.dynamiteplantfood.com) which happens to do its best in the hottest climates.
We here at www.slowreleasefertilziers.com are big fans of Dynamite and its ownership company Florikan, good people, good products, and great results.