Hardy hibiscus is a taste of the tropics in the colder climes of Zone 4.
These exotic beauties show off dinner plate-sized crepe paper blossoms in colors in all shades of red and pink, white and yellow, even plum, and bi-colors, with various eye patterns and streaking through the petals.
These are wow-worthy and wonderful perennial garden plants.
The blooms grow on large, fast-growing bushes that can survive our harsh winters as low as minus 30 F. They can be planted from June through Labor Day.
The National Garden Bureau has declared this the “year of the hardy hibiscus.” Plants can range in size from 2 to 10 feet tall. Flowers can measure up to 10 and 12 inches in diameter. Foliage can vary in color from green to bronze and near black. Old-fashioned varieties have large leaves, but foliage and plant size can vary on newer varieties.
Although perennial, hardy hibiscus are notorious for their late appearance in spring. Many gardeners give up and dig up their plants, mistakenly believing they are dead. Generally sprouts begin appearing when soil temperature is about 70 F, and some years that can be early June.
So, don’t grow anxious or impatient – you’ll soon see stems rise above the soil surface – and they’ll grow an inch per day. Blooms usually appear in late summer until a killing frost. Plants then die back, and you can trim off the spent stems.
Not to be confused with tropical hibiscus, hardy Hibiscus moscheutos belongs to the Malvaceae family, which also includes hollyhocks, mallow, malva and Rose of Sharon. In some parts of the country, H. moscheutos is also commonly called mallow.
Hardy hibiscus perform best with consistent watering, especially after transplanting. If your plant is losing lower leaves or aborting buds, you may need to increase watering. Their love of water makes them perfect for rain gardens or for planting in wet or boggy areas in the yard or garden.
Try planting your hibiscus in the midst of spring-blooming bulbs. The bulbs will be out of bloom when hibiscus emerges, and the hardy plant will soon conceal bulb foliage that should be allowed to fade back naturally.
Hardy hibiscus also need elbow room – a mature plant can be 5 to 6 feet wide. Plant them in full sun. In too much shade, hibiscus will become floppy and flowering will be reduced.
They prefer slightly acidic soil. It’s OK to lightly fertilize around the base of the plant using 10-4-12, 9-3-13 or 10-10-10. Don’t go overboard. Too much phosphorus can kill hibiscus.