The question is always the same: "I have just seen these gigantic white, pink, lavender or red flowers. What are they?"
The answer, of course, is hardy hibiscus.
Upon hearing this, many comment that they've seen hibiscus in Hawaii or the Caribbean but never knew they grew here.
Hibiscus moscheutos, commonly known as rose-mallow, are large, fast-growing plants that almost seem out of place in local gardens. These exotic flowers appear on plants that are native to marshy areas of the southeastern United States. The plants grow up to 6 feet tall, spread even wider and produce flowers 10-12 inches across from July through September.
The mallow family boasts some attractive members spread across more than 200 species of deciduous and evergreen trees and shrubs, plus annuals and perennials. Most are found in tropical and semitropical environments throughout the world.
In addition to the hardy and tropical hibiscus, other members of this family include the Althea (Rose of Sharon), prairie mallow, hollyhock, lavatera, cotton and okra. And like most families, there are a few less desirable members, including the common mallow or "cheezit weeds."
Hibiscus prefer full sun but will grow in areas that offer light shade. Because the large flowers are somewhat fragile, select a spot where they are not subjected to hot, dry winds.
Like most plants, good soil makes the plants easier to grow, but they tolerate sand and clay if you are careful about the watering. They do not like highly alkaline soil, nor do they like salty water or soil.
Most people prefer to buy hibiscus plants, although you can root cuttings in pots or by layering them in the garden. They root like weeds, but it takes time to develop a strong plant that will thrive in the garden.
All of the varieties listed are hardy to at least USDA zone five, so they will thrive along the Wasatch Front, although they do better when covered with a layer of mulch during the winter. They are herbaceous perennials, so do not be alarmed when they die back to the ground with the frost. They will emerge the following spring and grow even bigger the following season.
Because of space constraints, it is impossible to list all varieties, but here are some old favorites and some are new ones you might want to try.
Anne Arundel features pink flowers, 9 inches in diameter, that are produced on plants 5 feet tall. Blue River II is an older cultivar noted for its 10-inch white flowers. Crimson Wonder has crimson, 12-inch flowers on 5-foot plants.
Disco Belle Mix has 10-inch flowers that range in color from white to dark red. Lady Baltimore produces pink flowers with red centers on a 5-foot plant, and Lord Baltimore features red, 10-inch flowers.
Mallow Marvels features red, white and pink 6-inch flowers on 3-foot plants. Southern Belle offers mixtures of red, pink and white 10-inch flowers on 3-foot plants. Super Rose produces pink flowers on 3-foot plants. Sweet Caroline has ruffled pink flowers with dark centers and veins on plants that are up to 6 feet tall. The flowers on Turn of the Century are red and pink, the plant is 6-8 feet tall.
Some local nurseries now carry the Fleming series of hibiscus, developed by three brothers in Nebraska. These are hardy to 30 degrees below zero. Kopper King grows up to 4 feet and has 12-inch white flowers with a red and hot pink eye-zone that streaks to the petal edges. The leaves are copper red and have a maple cut shape.
Plum Crazy has 10-inch plum-colored flowers. Old Yella reaches 4 1/2 feet with 12 inch ruffled, luminescent flowers. Fantasia has 9-inch lavender-gray, ruffled flowers and a nice compact habit (about 3 1/2 feet).
Fireball grows 4 feet tall with 12-inch bright burgundy blooms. Crown Jewels get only 2 1/2-feet tall with yellow buds that are followed by a creamy white flower with a slightly streaking red center.
Royal Gems have 12-inch pink flowers that overlap on this 4-foot plant. Robert Fleming is 3 feet tall with hydrangea-like foliage and very dark red, overlapping flowers.
The Carafe and Splash series from Yoder/Green Leaf Perennials are also new. The Carafe series is 3 feet tall with Bordeaux (deep pink-red), Chablis (pure white) and Grenache (pure pink) flowers. The Splash series has Pinot Noir (red) and Pinot Grigio (light blush) flowers on plants 2-3 feet tall.
The Luna series from PanAmerican is a great 2003 seed-grown release with two colors — red and a blush (white with pale pink edges and overlay).
Larry Sagers is the horticulture specialist for Utah State University Extension at Thanksgiving Point.