Hibiscus' big, showy flowers make them a garden treasure

By Larry Sagers

For the Deseret News

Published: Sunday, Aug. 26 2012 2:00 p.m. MDT

The Southern Belle series of hibiscus features 10-inch flowers on 3-foot plants.

Larry Sagers, Larry Sagers

From the woody Rose of Sharon we discussed last week, we move to another mallow family member. This is among the showiest flowers that grow in Utah.

If you are lucky enough to have some, count your blessings. If not, you have a wonderful treat to add to your landscape.

For those that think hibiscus is relegated to a potted plant or tropical islands, read on. Hibiscus moscheutos, more commonly known as rose-mallow, is a large, fast-growing perennial flower. The plants are native to marshy areas of the eastern United States.

The plant size varies, but they can grow to 6 feet in height and can spread even wider. It is not the plant, but the stunning 10- to 12-inch diameter flowers that make this a garden treasure.

Choosing a spot for growing your plants is relatively easy. They prefer full sun but will grow well in partial shade. They also need some protection from hot, dry winds so the large, beautiful flowers are not damaged.

Like most landscape plants, good soil makes the plants flourish. They tolerate sandy to clay soil if they are watered correctly. Avoid highly alkaline soil or soil or water that is high in salts. Being native to swampy areas, they flourish with adequate water.

The plants make excellent specimen plants and also work well as a temporary hedge. If your landscape has low or wet spots where water accumulates, or if you have a natural stream or pond without a liner, they grow well there.

The plants are rated cold hardy to USDA zone five, so they thrive along the Wasatch Front. Unlike their woody mallow cousins, they die back with the fall frost. Clean them up by cutting the stems back to approximately 3 to 4 inches. In colder areas, add a covering of mulch during the winter.

The new shoot growth emerges slowly in spring, but don't be alarmed.

Once the shoots start, the plants grow rapidly. Because of the tremendous leaf and flower growth, make certain that they have adequate fertilizer and add to that as needed during the growing season.

However, once new growth begins, it proceeds quite rapidly, and the plants will benefit from regular fertilization during the growing season.

Well-grown plants produce an abundance of blossoms from July through September.

Although the plants are easy to root from cuttings or propagated by layering the plants in the garden, most gardeners purchase their plants from local nurseries. The plants also grow from seed. Rooted cutting sometimes take time to develop a strong, freely blooming plant.

In Utah, there are few pests that bother the plants. Occasionally, aphids and whiteflies will attack the plants, but these are usually controlled by natural predators. Foliage diseases are uncommon, and the plants are somewhat resistant to grazing deer.

Although there are many attractive, showy cultivars of this plant, plant breeders are not idle. Over the past few years there have been many new introductions, including some that will bloom well the first year from seed and are sometimes grown as annuals.

If you are looking for some taller plants consider the following:

Blue River II cultivar features 10-inch white flowers. Crimson Wonder has crimson, 12-inch flowers on 5-foot plants. Anne Arundel has pink flowers, 9 inches in diameter, that bloom on 5-foot plants.

Sweet Caroline has ruffled pink flowers with dark centers and veins. The plants grow up to 6 feet tall. The flowers on Turn of the Century are red and pink and the plant is 6 to 8 feet tall.

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