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DALY: Avoid using plants with invasive tendencies

In Georgia, we are fortunate that our climate allows for many garden plants to be grown. Both native and non-native plants beautify home landscapes. However, a few plants are invasive in nature meaning they can overtake the landscape and natural areas. Invasive plants pose a threat to the biological diversity of the local environment as well as cause economic harm.

What causes these plants to be so invasive? Over time, native plants in different parts of the world have evolved in a specific geographic location where they have developed strong interactions with the surrounding land, wildlife and each other. Climate and geographic factors have controlled their populations. However, when transported from their native environments to other parts of the world that lack these natural controls, these plants have the potential to spread rapidly and overrun local plant communities.

Kudzu, privet and Japanese honeysuckle are some well-known invasive plants. However, common ornamental landscape plants can also have invasive characteristics.

English ivy is frequently planted as a vine and as a ground cover. The plant is evergreen and has attractive foliage. Unfortunately, unless pruned continually, it will overtake areas crowding out other plants. English ivy can grow up trees and smother them. It can also make them more vulnerable to being blown over in windstorms.

Bradford pears have a poor growth habit where storms can cause limbs and sections of the tree to break. Although once thought to be sterile, they have been found to produce viable seeds that are easily dispersed. The trees grow rapidly and produce dense stands by root sprouts. They are more tolerant to adverse growing conditions, thus increasing their ability to invade ecosystems.

Thorny eleagnus is a dense evergreen shrub that produces long shoots that can grow into adjacent trees. It has copper colored leaves that are sometimes variegated. The shrub thrives in harsh environments and has a rapid growth rate. It also has fragrant flowers in the fall and produces a small olive shaped red fruit. Birds and other animals disperse the seeds to adjacent areas. They are frequently found growing along roadsides.

Frequently vincas are planted as groundcover. The plants produce a blue to violet colored flower and have woody vines. They form dense mats and extensive infestations by developing adventitious roots at the nodes. The plants thrive under the canopies of trees and in other areas with shade.

Several other ornamental plants are invasive as well. The southern magnolia is native to South Georgia, but in North Georgia it can escape cultivation and has invasive tendencies. Leatherleaf mahonia is more frequently found growing out of control in natural areas. Burning bushes, nandinas and the ornamental grass miscanthus also have invasive characteristics. Although not quite as troublesome in our area, miscanthus grass has overtaken large forested areas around Asheville, N.C.

The best course of action is to avoid the using these plants that have invasive characteristics. If you decide to plant them, keep them under control by pruning and by removing ones that are found growing in areas where they are not desired.

Gwinnett County Extension is offering a free class on invasive plants on Wednesday, July 30, from noon to 1 p.m. at the Gwinnett County Extension office located at 750 Perry St., Suite 400, Lawrenceville, GA, 30046. Please contact the Extension office to register.

Timothy Daly is the Agricultural and Natural Resources Extension Agent with Gwinnett County Extension. He can be contacted at 678-377-4010 or tdaly@uga.edu.