Birdwatchers are often tempted to plant trumpet vine because its orange flower attracts hummingbirds. Experienced gardeners often know better, since this climber is aggressive to the point of being a nuisance. This deciduous woody vine suckers profusely from underground runners and also self-seeds rampantly. When it escapes garden location, it can form thickets in the wild that can choke out other plants.
The compound leaves are large (up to 15 inches) and are shiny dark green on the top surface and duller green on the undersides. The foliage is pinnately compound: The leaves are divided into multiple leaflets, and the overall look is feather-like. Clusters of trumpet-shaped yellow, orange, or red flowers up to 3 inches long appear from June to September. Leaves turn yellow in fall. After the flowers, 6-inch-long seed pods appear.
For gardeners willing to control it, trumpet vine can provide quick cover for fences, arbors, trellises, walls, and other structures. It can also blanket the ground to hide rock piles and refuse heaps. It is a good vine for hot, dry conditions, but it needs lots of room. Used carefully, it is excellent for hummingbird gardens.
- Botanical Name: Campsis radicans
- Common Name: Trumpet vine, trumpet creeper, cow itch vine, hummingbird vine
- Plant Type: Deciduous woody vine
- Mature Size: 30 to 40 feet
- Sun Exposure: Full sun to part shade
- Soil Type: Grows in any soil; prefers good-draining soils
- Soil pH: 3.7 to 6.8
- Bloom Time: June to September; peaks in July
- Flower Color: Yellow, orange, red
- Hardiness Zones: 4 to 9 (USDA)
- Native Area: Southeastern U. S. but has naturalized in many northern states
How to Grow Trumpet Vine
Trumpet vine prefers well-draining soil, but it will thrive almost any soil in a full sun to partial shade location. It is critical that there be a sturdy support structure for this vine, as it can overwhelm trees or buildings. Avoid planting it close to foundations, because the creeping vines can damage them. The vines can also creep under shingles and cause damage. Keep them away from trees, as the vines can strangle them.
Trumpet vine requires little care once established. Water them only during dry periods and never fertilize them. The most important maintenance is to prune them back, frequently and aggressively, to keep the vines under control. These vigorous growers do need to be contained if you do not want them spreading in an uncontrolled manner. This means some preventive maintenance on your part, but it will save you work in the long run:
- Faithfully pull up any new shoots that pop up from the root system.
- Remove the seeds before they fall on the earth and can germinate.
Trumpet vine will thrive in full sun to partial shade. Full sun will produce the best flowering.
These vines do well in almost any soil, but they grow most aggressively in well-drained soils.
Trumpet vine needs watering only when there are obvious signs of withering. In most climates, normal rainfall suffices to keep the plants healthy.
Temperature and Humidity
Trumpet vine's natural range is the hot, humid regions of the Southeast, but it will do well throughout the hardiness range. In dryer climates, the plant is easier to control.
Trumpet vine is such an aggressive plant that no feeding is recommended.
Varieties of Trumpet Vine
- C. radicans 'Aurea': This cultivar produces yellow flowers.
- C. radicans 'Flavea': This is another yellow-flowering cultivar.
In addition to the main species, Campsis radicans, there are two other species sometimes grown:
- Campsis grandiflora, also known as Bignonia chinensis, is native to East Asia and is hardy in zones 7 to 9. It blooms in late summer and autumn.
- Campsis x tagliabuana is a cross between C. radicans and C. grandiflora, and is hardy to zone 6. It has orange flowers and is less aggressive than C. radicans.
There are virtually no disease and pest problems that plague trumpet vine—a vigor that some people regard as unfortunate since rampant growth is perhaps the biggest problem with this plant. Where the plant becomes too much to handle, there are four natural methods recommended for killing it:
- Dig out the roots. Although it is hard work, digging out the plant's roots by hand will eliminate it.
- Kill the plant with hot water. Pouring scalding water on the plant's stems will kill it to ground level, but you will need to apply hot water several times as new growth sprouts up before the roots will be killed.
- Spray the plant with diluted vinegar. A half-and-half solution of vinegar and water sprayed over the foliage will eventually kill trumpet vine.
- Apply salt to the soil. Add a cup of rock salt to a gallon of hot water and pour it over the plant's root zone. Be aware, though, that this might kill other plants in the vicinity.
Trumpet vine may take several years before it flowers. Some conditions that might affect blooming include:
- Not enough sun
- Pruning at the wrong time: Trumpet vine blooms on new growth, so, pruning should be done before new growth begins for the year.
- Too much fertilizer: This is one plant where fertilizer, especially nitrogen, can hinder flowering.
Toxicity of Trumpet Vine
There is a skin irritant in trumpet vine that affects some people. This characteristic lends trumpet vine one of its common names—cow itch vine.
This is a plant for which it is almost impossible to prune too much. Early in the spring before new growth start, cut the plant back nearly to ground level, leaving only a few buds, This kind of aggressive annual pruning is the best way to keep the plant in check.