Trumpet Vines

Whether "Invasive" or "Aggressive," You Should Fear Their Spread

Trumpet vine (image) spreads so aggressively that many don't want it. Count me in that group.
David Beaulieu

Taxonomy, Botany of Trumpet Vines

Plant taxonomy classifies trumpet vine plants as Campsis radicans. Another common name is "trumpet creeper" (also spelled as one word).

Botanically speaking, trumpet vines are classified as deciduous woody vines.

Plant Features

These striking but problematic plants (see below) commonly bear clusters of orange, reddish-orange or salmon-colored flowers throughout much of the summer.

You can also buy cultivars with yellow flowers. Flowers are succeeded by 6-inch pods. Campsis radicans may climb a tree if given the opportunity and can reach a length of up to 40 feet. The foliage is pinnately compound (that is, the leaves are divided into multiple leaflets, and the overall look is feather-like).

USDA Planting Zones, Growing Needs

Native to the southeastern United States, trumpet vine plants can be grown in USDA planting zones 4-9.

Grow trumpet vines in full sun. Although they will grow in partial shade, they will bloom better in full sun. This is an example of a plant that, as strange as it may sound, will perform better in poor-to-average soil than it will in rich soil. A soil that is too rich may actually cause your plant to take a longer time to bloom (see below).

Creeper vs. Climber

Do not conclude from the alternate common name "trumpet creeper" that this plant is restricted in its growth to hugging the ground.

Especially if the vine receives a little help from you (training), it will climb. The species name, radicans is Latin for "growing roots" and refers to the aerial roots of trumpet vines. These aerial roots give them a modest ability to scale surfaces. They share this feature with poison ivy (Rhus radicans).

Trumpet vines are just one of many plants that can damage house siding if allowed to grow up a wall; others include:

Warning, and a Distinction Between "Invasive" and "Aggressive"

Trumpet vines do a lot of spreading and may naturalize in areas to which they are exotic, earning them the status of invasive plants in those areas. Even in their native range, these orange thugs are aggressive to the point of being a nuisance.

Note that there is a difference between the terms "invasive" and "aggressive." Technically, to be classified as invasive in a region, a plant must be foreign to that region. On its home turf, such a plant would be termed "aggressive," "thuggish," etc. Of course, to the gardener faced with the prospect of having to control trumpet vines, the point is merely academic: Regardless of what you call them, you have your work cut out for you.

These plants spread by suckering underground runners, as well as from seed. This makes them tough to eradicate. For example, the runners may push up between the branches of shrubbery and go undetected; all the while, they are taking in nutrients that keep the plant strong. The flip side of all of this aggressiveness is that they are useful in preventing soil erosion on a hillside.

Concerns over the plants' aggressiveness extends to use around your home, garage or outdoor storage shed: The suckers of their aerial roots can damage siding on buildings.

There is also a skin irritant in trumpet vines that affects some people.

Why Isn't My Plant Blooming?

While there is nothing bashful about the leafy growth of this plant, blooming is another matter. Trumpet vine may take years to flower. This is normal. It is simply a type of plant that takes a long time to bloom. So do not become discouraged or feel that you have necessarily been doing something wrong. Consult the following checklist. If you answer each question with a yes, then you just have to be patient and wait for your plant to mature:

  1. Is it growing in full sun?
  2. If you are pruning your plant, are you doing so in early spring? Trumpet vine blooms on new growth (new wood), so, if you wish to prune it at all, do your pruning before any new growth is put on for that year. If you are pruning later than this, you may be removing flower buds.
  1. If you are fertilizing your plant (which is often not necessary), are you using a fertilizer that is low in nitrogen? Nitrogen is the first number in the NPK sequence, which you can find printed on the fertilizer bag. Remember, fertility can be the enemy in getting these plants to bloom, so dial back the TLC a bit.

Care, Wildlife Attracted by Trumpet Vines

Most care issues revolve around containing trumpet vines: They are not for low-maintenance landscaping. Grow them on a sturdy garden arbor or wooden fence. This vigorous grower does need to be contained if you do not want it spreading all over the place. Faithfully pull up any new shoots that pop up from the root system, and remove the seeds before they fall upon the earth.

Birdwatchers are often tempted to plant trumpet vines because they draw hummingbirds. But other, better plants that attract hummingbirds are available, including some that require less work on your part.

Experience Is the Best (but a Hard) Teacher

Due to their widespread popularity, many gardeners have personal experience with trumpet vines. But it is often a bad experience. In many cases, the plants are simply inherited. Perhaps a deceased parent who was a hummingbird lover had seen trumpet vines advertised in a nursery catalog, touting them as great "hummingbird plants," and decided to plant some. The present-day gardener inherits the property in question, along with the problem caused by the aggressive nature of the plants. For, once established, they spread out of control. Decades later, the current generation of gardeners finds itself fighting an on-going battle in trying to rein in a pest that it never asked for, in the first place.