Perennial hibiscus, also known as rose mallow or hardy hibiscus, is a shrub that typically reaches 4 to 6 feet in height. It is commonly cultivated for its large, ornamental flowers that can reach up to 1 foot in diameter. The flowers bloom during summer and can be red, white or pink in color. Perennial hibiscus is relatively care-free and requires only routine watering and feeding to thrive.
Plant perennial hibiscus during early spring in a location that receives full sunlight throughout the day. Prepare the soil by spreading 1 inch of organic compost over the planting site and using a garden tiller to incorporate it into the soil to increase fertility.
Soak perennial hibiscus seeds in warm water for one hour prior to planting to induce germination. Sow each seed about 1 inch deep and space each planting about 3 feet apart. Water immediately after planting to compact the soil around the seeds and initiate growth.
Spread a 2-inch layer of mulch over the soil surrounding perennial hibiscus plants to reduce weeds and increase moisture retention. Start the layer at least 3 inches from the base of the hibiscus to allow air circulation and reduce risk of disease.
Water perennial hibiscus once every four days until the sprouts emerge from the soil. Reduce frequency thereafter to once per week. Never allow the soil to dry out completely, as the plant will begin to wilt almost immediately.
Feed perennial hibiscus in spring with a high nitrogen 12-6-6 NPK fertilizer. Continue fertilizing once every six to eight weeks until winter. Cease fertilizing until the next spring. Apply fertilizer following the instructions provided by the manufacturer.