Victoria County Master         Gardener Association

A ROSE IS A ROSE IS A ROSE UNTIL IT'S NOT

ROSE OF SHARON (ALTHEA)

Not really a rose

August 23, 2019

PHOTO CONTRIBUTED BY TEXAS A&M AGRILIFE RESEARCH

The White Angel Althea shown here is one of the newest Texas Superstars along with a counterpart, the Blue Angel, announced earlier this year in May.  White Angel features a crisp white blossom larger than most varieties and blooms all summer long.  The plant produces continuous flowers all throughout its blooming season.

Althea (hibiscus syriacus) is an old-fashioned, deciduous shrub that blooms from spring through the summer.

Derivations

Its other common name, Rose of Sharon, first appears in The King of Solomon. According to Wikipedia, a Hebrew phrase was translated by the editors of The King James Version of the Bible as Rose of Sharon; however, previous translations had rendered it simply as “the flower of the field.’”

Regardless of how it got its name, Rose of Sharon was a staple of gardens of the past. Its long flowering period from early spring through summer and multiple flower forms and colors made it a favorite of gardeners across the United States.

Uses in the garden

The Rose of Sharon is a deciduous shrub or small tree that has an upright form. It can be maintained as a shrub, a large shrub or a small tree. The shrub can be used as a single specimen in the landscape, or planted in groups or as a hedge.

Physical Characteristics

Altheas can grow as tall as 10 to 12 feet. Their width is generally 5 to 7 feet. According to Dr. William C. Welch, landscape horticulturist, heavy pruning can control size and leads to vigorous growth and heavy blooming. He also states that some varieties tend to be “leggy” and that by pruning lower limbs near the trunk, the plant will resemble a small tree.

Since the plant is deciduous, pruning should be done in the winter or after the plant has finished blooming for the season.

Colors range from white to pink, lavender and reddish purple. Some of the new cultivars tend to be shades of blue. So, there is a color to fit all garden schemes.

Earth-Kind rankings — ideal plant for this area

Texas A&M and Texas A&M AgriLife Extension have developed an approach to gardening that is called “Earth-Kind Landscaping.” The 1-10 scale rates plants in five areas: heat tolerance, water requirement, soil requirements, pest tolerance and fertility (fertilizer needs). The Rose of Sharon scored a 9 on the scale.

The althea’s lowest ranking is in pest tolerance as the plant is susceptible to aphids, spider mites, and white fly. However, all of these pests are easily controlled.

As for the other points on the scale, the Rose of Sharon has high heat tolerance, low water use, low soil requirements, and low fertility requirements. All of these qualities make it an ideal plant for our area.

Designated Texas Superstar

On May 9, 2019, Texas A&M AgriLife named both the Blue Angel and White Angel Altheas as Texas Superstars.

• Blue Angel

According to the press release, the Blue Angel features “single blue, broadly trumpet-shaped flowers” and is a cross between Bluebird and Diane altheas.

• White Angel

White Angel althea “features a larger final size and numerous clean, white flowers.” According to Dr. Mike Arnold, Texas A&M AgriLife Research horticulturist, both of these plants have “unique colors. The stone blue is vibrant and the white is … crisp.”

Cotton root rot main problem

Other than insect problems, Dr. Welch notes only a few other concerns with this plant. The main one is cotton root rot, a fungal disease that is found throughout the Southwest.

It will cause sudden wilt and death of affected plants. It usually strikes in the warmer months and is difficult, if not impossible, to control. The plants may experience bud drop if they are under stress from too much or too little water.

Propagation

The Rose of Sharon is easily propagated.

• By seeds

Plants can be started from seeds and will often self-sow. However, according to the Aggie Horticulture website, the volunteer seedlings can become weedy and invasive. Also, the seedlings may not stay true to the parent plant.

• By cuttings

The preferred method is to take stem cuttings 10 to 12 inches long. The cuttings should be taken during the winter and stuck in any good garden soil. They should be watered periodically and should be ready for transplanting in the fall.

Varieties

While it is true that the Rose of Sharon is an old-fashioned plant, several new hybrids have been developed beginning in the ’60s. (So, OK – that’s still old).

According to the Plants Database from the National Gardening Association, 315 plants have been added to the Rose of Sharon database since 2011, so there is a lot of interest in this plant. One nursery I recently visited had five or six varieties. They had colors ranging from white with a red throat to an almost blue double flower.

Good choice

Rose of Sharon or althea is a great plant for our area. A long blooming season, multiple blossoms and low maintenance make it a winner in any garden setting.

PHOTO CONTRIBUTED BY CHARLIE NEUMEYER/VICTORIA COUNTY MASTER GARDENER

Rose of Sharon can be found as large as 5- to 7-foot wide shrub or small tree.  This shrubby example shown here is one of several varieties growing at Victoria Educational Gardens at Vicgtoria Regional Airport.  It was pruned in early spring to encourage dense growth.  Of note is the white with read throat conformation of the blooms with numerous buds all over the plant.  While the blooms are not large, the plant sports multiple flowers all summer long in full sun and heat with low maintenance.