Although its foliage is lovely, the hibiscus is grown for its incredibly large and colorful tropical flowers. Processes need to take place within the hibiscus for it to produce these beauties, and some of them require your assistance. Adequate water and fertilizer go a long way toward making the hibiscus bloom. The correct fertilizer helps even more. Fertilizers high in nitrogen promote foliage growth at the expense of hibiscus flowers. On the other hand, hibiscus has a voracious appetite for potassium, which is involved in every process the plant undergoes but is essential in blooming. Finally, phosphorous should be given in moderation as, over time, it can damage the hibiscus and cause failure to bloom.
Grow the hibiscus in full sun. It does not flower in the shade.
Water the hibiscus to keep the soil moist at all times. When the weather is hot, you may need to water daily or even twice a day. The hibiscus requires lots of water to maintain its foliage and produce strong flower stems.
Fertilize the hibiscus to build larger and more flowers. Growers at Hidden Valley Hibiscus suggest a 17-5-24 formula and state that if you can't find that exact formula, to use one that is close. Use half the rate recommended on the label every time you water the hibiscus.
Prune the hibiscus in early spring to increase flowering. Cut each branch back by one-third, cutting them 1/4 inch above an outward-facing leaf node.