Fortunate is the gardener who lives in a tropical zone suitable for growing the lovely and showy tropical hibiscus. Because tropical hibiscus plants are hardy only to USDA zones 9 and 10, they are extremely sensitive to frost damage. When you select a sunny location, a hibiscus plant should grow to approximately 5 feet tall. Some gardeners allow hibiscus plants to grow as a shrub and others prefer to grow them as ornamental hedges.
Prepare the sunny growing area in the spring. Work the soil with the garden spade to a depth of 3 to 4 inches. Add 2 inches of compost to the top of the soil, and cultivate the soil again with the garden spade to incorporate the compost.
Dig holes for each tropical hibiscus with the shovel. If you plan to grow the tropical hibiscus as a shrub, space each hole approximately 5 feet apart. If you plan to grow the hibiscus as a hedge, space each hole 2.5 feet apart. Make the holes the same depth and width as the root systems of the hibiscus plants.
Remove the hibiscus plants from their temporary containers carefully. Loosen the soil by placing the containers on their sides on the ground and rolling them back and forth while you press in the sides of the containers. Pull the hibiscus plants gently up from the containers, and transfer them immediately to the prepared holes. Fill in the soil around the plants so the soil is even with the surrounding soil level, and tamp the soil down firmly with your hands.
Water the hibiscus plants immediately after you finish planting them, saturating the soil evenly. Keep the hibiscus plants evenly watered, and do not allow the soil to dry out at any time during the growing season.
Fertilize the hibiscus plants once per month by mixing the fertilizer with water according to package recommendations. Pour the fertilizer carefully over the soil without splashing any fertilizer onto the foliage.
Prune the hibiscus to remove the newest growth at the end of the winter. Shape the plant as you desire, taking off as much as one-third of the newest growth. Keep in mind that you may remove future blossoms as you prune, so minimize pruning to maximize blooms.