If you’re looking for summer flower power, look no further than hardy hibiscus.
This plant has it all:
It’s the kind of crop growers like to produce because it’s so fast. It’s a plant retailers like to sell because it almost jumps off the shelves when in flower. And it’s a plant gardeners love to grow because it’s foolproof, tough as nails and reliable. In fact, this is the kind of plant that any budding gardener can grow successfully, giving them confidence to move on and try other species. What’s not to like?
Hibiscus moscheutos and other native species are parents of the cultivated hardy hibiscus, also known as perennial hibiscus or rose mallow. A cousin of okra and cotton, hardy hibiscus is also closely related to tropical hibiscus, confederate rose, and Rose-of-Sharon.
Unlike its woodier relatives, hardy hibiscus is a herbaceous perennial producing multiple cane-like shoots that emerge in late spring, flower in summer and die back with autumn frost.
Hardy hibiscus requires the long days of summer to initiate flowers. Buds form in leaf axils near branch tips and open into the exotic-looking flowers typical of hibiscus, each with five petals surrounding a prominent pistil. Flowers last just one day, but so many buds form that the plant appears perpetually in flower throughout summer and fall until frost.
Easy to produce
Hardy hibiscus is on the ever-growing list of “crossover” crops produced by greenhouse growers and traditional outdoor nursery growers. Finished plants can be produced from seed, plugs or cuttings in eight to 14 weeks, depending on liner size, growing conditions, time of year and cultivar.
Standard procedures will suffice, with only high light and high temperatures needed for fast growth. Long days are required for flower bud development. Although hibiscus is considered a heavy feeder, frequency of fertilization matters more than amount. Over-fertilized plants will grow too large and not flower well, whereas nutrient-deficient leaves will turn yellow.
Uniform soil moisture is necessary, too. Plants allowed to wilt respond with leaf yellowing and leaf drop (reducing plant quality) and produce fewer flower buds. Keep plants jammed pot tight until canopies of neighboring plants touch, then space to reduce stretch. This allows the development of bushy, compact plants. Some growers use plant growth regulators on hardy hibiscus. But these products — and pinching or pruning — are less important on newer, self-branching cultivars.
Packs a punch
Hardy hibiscus is one of the most gratifying plants a gardener can grow. Few other perennials provide as much bang for the buck in terms of flower size, length of flowering and ease of care. Hardy hibiscus grows best with full sun in rich, moist soil but tolerates even the poorest, sandiest soil if mulched and watered once in a while.
Flowering is promoted by plentiful rain and sunshine. No matter how much and how often you irrigate a landscape, nothing beats good rain when it comes to stimulating flowering.
Hardy hibiscus is cold hardy from USDA Hardiness Zone 9-4. Plant emergence and subsequent flowering begins in late spring in the lower South and occurs progressively later moving north, with flowering in late summer in the northern United States and Canada.
As with many perennials, some hardy hibiscus won’t return after winter dormancy, especially some of the newer, more refined cultivars. Still, most plants return year after year, and hardy hibiscus gets better with time. Older plants tend to emerge sooner in spring, grow larger, flower sooner and produce larger flowers than young plants.
Hardy hibiscus is fairly pest resistant. While an array of minor pests can attack plants, the most devastating pest is the larvae of hibiscus sawfly. This pale-green caterpillar like larvae is gregarious, meaning several often feed on the same leaf or plant. It can quickly defoliate entire plants.
Here are a few of our favorites
Blue River Hibiscus
Its hard to believe that this tropical looking plant is hardy to zone 4! Enormous, dinner-plate sized white flowers explode from robust, shrub-like plants. Blooms begin to appear in mid-summer and continue to unfurl right up until the first frost. Blue River is continued to be a heavy bloomer and with age the flowers get larger and larger. The pure white flowers of this Hardy Hibiscus have no contrasting eye, making them perfect for the all white or moonlight garden. The leaves of Blue River have a subtle hint of blue in them creating a very elegant backdrop for the large white flowers. Introduced by Dr. Harold F. Winters who found this beautiful perennial growing along the bank of the Blue River in southern Oklahoma – hence the name. Hibiscus are true sun lovers and need a rich moist soil. While Hibiscus will grow in dryer soils, providing the plants with adequate water will reward you with larger blooms and lush foliage.
Turn of the Century Hibiscus
Turn of the Century is a very tall, vigorous, sturdy, erect hibiscus typically growing 6 to 8 feet high and features dinner plate-sized, five-petaled, hollyhock-like flowers. Turn of the Century has beautiful bi-colored blossoms with petals ranging from red to light pink, looking very much like a pinwheel. Each flower has a prominent, pale yellow, tubular central steminal column. These beautiful blooms are shown off perfectly with the green cut leaf foliage. This plant seems to do well in Central Texas in a little afternoon shade. In cooler climates, it will do well in full sun. Turn of the Century is a real showstopper! It is hardy thru zone 5 and has no insect or disease problems. This plant will be beautiful in a large container or as the feature plant in the border. Don’t miss this lovely plant.
Ann Arundel is like cotton candy. Ann Arundel is a compact, vigorous, sturdy, erect, woody-based hibiscus cultivar that typically grows 4 to 5 feet tall and features dinner plate-sized (up to 9 inches), five-petaled, hollyhock-like flowers. Flowers are clear pink. Each flower has a prominent and showy central staminal column. Ann will have lots of blooms up and down the stem — meaning you are going to get a bunch of blooms at one time and they just keep coming. We grow ours in a large container, and it is a large bouquet in bloom. Absolutely stunning! Hardy thru zone 4 with no serious insect or disease problems.
Lady Baltimore is so very much a lady in the hibiscus world. Rather tailored, cupped blooms of a soft pink but then she has a bright enamel red eyezone. Quite a contrast. Makes for a very pretty, different specimen in the landscape. Beautiful, dark green lobed leaves sets this beauty off perfectly. Lots of blooms all summer. Definetely a “What’s that?” kind of plant. Hardy thru zone 4 with no serious insect or disease problems.