Good news for lovers of hibiscus (H. rosa-sinensis): 200 new varieties of these exotic flowers offer outstanding flower color and size on compact plants. Developed by Charles Black, owner of Topanga Tropicals in Los Angeles, they are easier to grow than other hibiscus, and the flowers are more colorful and longer-lasting.
Depending on the variety, the grafted plants grow 4 to 8 feet tall (grafting keeps them compact). They make excellent container plants, perfect for northern gardeners who grow their hibiscus indoors in winter and outdoors in summer. For gardeners in USDA Hardiness zones 9 and 10, where these small plants are hardy, they fit nicely into perennial borders. These hibiscus will also tolerate a little more shade than their full-sized predecessors.
Many of the varieties have flowers with very dramatic size and coloration. Some of the most colorful include 'Double Date', with ruffled pink double blooms that resemble camellias; 'Harvest Moon', with bright yellow petals and a clear white throat; ' Lora ', with ruffled, red-throated lavender-blue flowers; and 'Donna Lynn', with yellow-lavender-red flowers.
Flowers of some varieties grow to a foot in diameter, although temperature and fertilizer can influence their size and color. Ideal growing temperatures are 60&Deg to 90° F, but in warm weather flower size increases, and yellow or white splotching and other highlights become more visible. In cooler weather, red and orange tones predominate, and markings can disappear. With temperatures above 95° F, flower size shrinks, buds drop, and leaves may turn yellow and fall off.
Like all hibiscus, these new varieties need plenty of water and fertilizer during warm weather. To produce larger, more attractive flowers, Black recommends using a water-soluble fertilizer that's low in phosphorus and high in potassium (10-5-15). During cold conditions, cut back on watering and fertilizing, giving only enough to keep the plants healthy. Use a well-drained potting soil for container plants, and when transplanting, handle the delicate rootball carefully. Control whiteflies and aphids with insecticidal soap or neem oil.
For these and other new varieties, check local nurseries or Topanga Tropicals, (310) 455-7284, www.exotic-hibiscus.com.
Article published on June 23, 2008.