Trumpet vines are best planted in the spring or early fall. It is both a fast-growing plant and one that can live for many decades if given a favorable garden location. Trumpet vine is mildly toxic to people and animals. Trumpet vines require little care in order to thrive. Fertilization typically is not necessary and watering usually is only required during periods of drought. But trumpet vine is still a high-maintenance plant, as aggressive regular pruning is mandatory in order to control growth and spread. Removing unwanted shoots from your lawn, and removing seed pods to discourage self-seeding are all tasks necessary for keeping trumpet vine under control. The seeds are similar to milkweed seeds, with each seed attached to white fluff that allows the seeds to be carried by the wind. It’s advisable to use gloves when handling seed pods and seeds.
Light
Trumpet vines can grow in full sun to partial shade. Full sun, meaning at least six hours of direct sunlight on most days, will produce the best flowering.
Soil
These vines can tolerate a wide range of soil types, including sandy, loamy, and clay soils, and have a natural affinity for soils that are moist but well-drained. In native locations, they are often found in seasonal swamps and forest thickets.
Water
Trumpet vines like a moderate amount of soil moisture but have good drought tolerance. In general, they only need watering when there are obvious signs of wilt and withering. In most climates, the typical rainfall will be sufficient to keep the plants healthy. About 1 inch of water per week—through a combination of rainfall and/or irrigation—is entirely sufficient for good plant performance.
Temperature and Humidity
This plant’s natural range is the hot, humid Southeastern United States, but it is hardy in zones 4 to 9. In less humid climates, the vine is less vigorous and easier to control.
Fertilizer
Because trumpet vines are such aggressive spreaders and can thrive in lean soil, no supplemental fertilization is recommended.
Types of Trumpet Vine
There are several named trumpet vine cultivars, including:
Campsis radicans ‘Apricot’ is somewhat more compact and less invasive than the main species plant, and it produces apricot-colored blooms.C. radicans ‘Flava’ has showy golden flowers that stretch around 3 inches long. C. radicans ‘Indian Summer’ is an especially hardy variety and sports yellow-orange blooms.C. radicans ‘Crimson Trumpet’ is an aggressive grower with bright red-orange flowers.C. radicans ‘Judy’ has yellow flowers with orange streaks on the throats. It has excellent frost tolerance.C. radicans ‘Atropurpurea’ is a bright red cultivar, hardy to zone 5.
Pruning
It is almost impossible to prune this vigorous plant too much. Trumpet vines bloom on new stems, so prune early in the spring before growth starts. Cut the plant back to nearly ground level, leaving only a few buds. It is also okay to cut back in late autumn after the leaves have dried and fallen. This kind of aggressive annual pruning is the best way to keep the plant in check. Vines can also be cut back throughout the season although you may be sacrificing a few blooms. If you want to grow the vine on a structure like a garage or outbuilding, try hanging wire across the surface. This gives the trumpet vine something to attach to and makes it easier for you to take care of necessary pruning throughout the growing season.
Propagating Trumpet Vine
Trumpet vine can be reproduced by many methods, but the easiest way to to simply dig up one of the suckering runners at the point where it emerges from the soil, then transplant it to the desired location. This is best done in the spring as the new growth is just emerging.
How to Grow Trumpet Vine From Seed
This plant readily self-seeds itself, and it is an easy matter to carefully dig up a volunteer seedling and transplant it wherever you want a new plant to grow. Plant the seedling so the crown is right at soil level. It’s also easy to collect seeds from the bean-like capsules left behind after the flowers fade, then direct-sow them in the desired location.
Potting and Repotting Trumpet Vine
Trumpet vine makes a surprisingly good container plant, as this method of growing makes it much easier to control its rampant spread. But it will take a very large, heavy container, such as a half-barrel or 20-plus gallon concrete or ceramic planter. Fill the container with general-purpose potting mix, and equip it with a sturdy climbing trellis at the same time you plant the vine. As with in-ground plants, be sure to dig a hole that’s big enough to fit a bottomless bucket container, so it prevents the trumpet vine from spreading its roots and possibly damaging other plants. Gently loosen the roots of plants and place it into the soil, preferably with something that will give it support like a trellis. Be prepared to prune back the vine to just above soil level on a yearly basis in the late fall or early spring. ‘Apricot’ and ‘Indian Summer’ are good cultivars for containers, as they are somewhat smaller than other varieties.
Overwintering
When planted within its recognized hardiness zone, this plant requires no winter protection. However, to keep it from overrunning an area, it’s best to prune it severely in late fall or early winter—and certainly no later than early spring.
How to Get Trumpet Vine to Bloom
Given full sun, there’s almost no way to prevent this plant from blooming robustly through the entire summer. The only hindrance to good blooms is if pruning is done too late in the spring, removing the new growth upon which the flower buds form. Excessive feeding may stimulate extremely aggressive green growth at the expense of flowers. Generally speaking, these plants don’t need any feeding at all in order to bloom and they respond better to neglect than to fussy attention.
Common Problems With Trumpet Vine
The most common complaints about trumpet vine don’t involve cultural problems, but rather growth that is too vigorous:
Uncontrollable Spread
Fire Hazard
Trumpet vine is a highly flammable plant, so it is a poor choice for planting next to foundations or building walls in regions where wildfires are a known hazard. A neglected plant that is not pruned back annually can envelop a home or garage in a manner that creates a serious fire risk. After cutting away the trunk, the roots should be dug out using a trowel or shovel. Small shoots that pop up in your lawn can usually be kept in check by keeping them mowed down with the grass. As a last resort, an herbicide can be applied. Choose the correct spray by checking the label to make sure trumpet vine is on the list of plants affected. Cut the vine back as close to the ground as possible and spray the stump. Then cover the stump with an old coffee can or something similar. If necessary, protect neighboring plants with a cardboard shield to avoid overspray when applying herbicide.
