What is an invasive plant?
The USDA Forest Service defines an invasive plant as a “non-native plant to the ecosystem under consideration whose introduction causes or is likely to cause harm to the economy, environment, or human health." Each state in the US has a listing of plants that are considered invasive or noxious weeds in that state. Those plants deemed invasive or noxious weeds are normally not available for sale within the state to help limit their spread.
What makes an invasive plant so successful?
Invasive plants have the ability to spread quickly and are difficult to control. Most are successful because they produce abundant seeds that spread over large areas (via wind, water, or animals). They may also produce dense, spreading root systems. Invasive plants are often highly adaptable to difficult sites or inhospitable soils. Ultimately invasive plant species outcompete native plants in managed and wild landscapes.
What are some common invasive plants for Iowa?
Tree-of-Heaven (Ailanthus altissima), Japanese barberry (Berberis thunbergia), multiflora rose (Rosa multiflora), purple loosestrife (Lythrum salicaria), dame’s rocket (Hesperis matronalis), honeysuckle (Lonicera), velvetleaf (Abutilon theophrasti), oriental bittersweet (Celastrus orbiculatus), and others are listed as invasive plants on the Iowa DNR invasive plants website. Noxious weeds of Iowa are determined by the state legislature and the Iowa Department of Agriculture and Land Stewardship. The Midwest Invasive Plant Network lists invasive or potentially invasive plants for Iowa and surrounding states. For assistance in identifying some of the invasive plants on these lists, check out resources (including identification videos) from Iowa State University Department of Natural Resources and Ecology Management.
Are all non-native plants potentially invasive?
Not necessarily. This is a difficult question to answer as it depends entirely on the species in question. There are probably several plants in your home landscape that are not native to Iowa that are not considered aggressive – let alone invasive. Peonies, tulips, hosta, and lilacs are some non-native plants typically found in home landscapes that are rarely considered invasive. Yet, there may also be a few non-native plants that are considered potentially invasive in your home landscape – like burning bush and barberry.
How do I control invasive plants in my landscape?
There are several options for control of aggressive and invasive plants.
Ideally, control starts with prevention. This means not planting a plant species that may be considered an aggressive spreader and/or eliminating it in the landscape if it becomes too aggressive – before it is ever considered an invasive plant. Researching a plant thoroughly prior to planting can be difficult when new cultivars are being introduced each year with limited long-term information on growth rates and the ability to spread.
Therefore, removal options are important considerations for homeowners with invasive plants in their landscapes. Digging, hand-pulling, repeatedly pruning, herbicides, blocking light with coverings, and even burning in some areas are methods used to kill or remove unwanted or invasive plants. Often multiple methods must be used for best control. Researching the plant in question can offer guidance on control or elimination methods. Persistence is also key as it often takes several years to effectively control or eliminate some invasive plants.
Links to this article are strongly encouraged, and this article may be republished without further permission if published as written and if credit is given to the author, Horticulture and Home Pest News, and Iowa State University Extension and Outreach. If this article is to be used in any other manner, permission from the author is required. This article was originally published on January 7, 2022. The information contained within may not be the most current and accurate depending on when it is accessed.