Whether you’re already growing trumpet vine in the garden or you’re thinking about starting trumpet vines for the first time, knowing how to propagate these plants certainly helps. Propagating trumpet vine is actually pretty easy and can be done in a number of ways — seed, cuttings, layering, and division of its roots or suckers.
Note: While all of these methods are easy enough, it’s important that everyone be aware that these plants are poisonous and not just when ingested. Contact with its foliage and other plant parts, especially during propagation or pruning, can result in skin irritation and inflammation (such as redness, burning, and itching) in overly sensitive individuals.
How to Propagate Trumpet Vine from Seed
Trumpet vine will readily self-seed, but you can also collect and plant the seeds in the garden yourself. You can collect seeds once they mature, usually when the seedpods begin to turn brown and split open.
You can then either plant them in pots or directly in the garden (about ¼ to ½ inch (0.5 to 1.5 cm.) deep) in fall, allowing the seeds to overwinter and sprout in spring, or you can store the seeds until spring and sow them at that time.
How to Grow Trumpet Vine from a Cutting or Layering
Cuttings can be taken in summer. Remove the bottom set of leaves and stick them in well-draining potting soil. If desired, you can dip the cut ends in rooting hormone first. Water thoroughly and place in a shady location. Cuttings should root within about a month or so, give or take, at which time you can transplant them or let them continue growing until the following spring and then replant elsewhere.
Layering can also be done. Simply nick a long piece of stem with a knife and then bend it down to the ground, burying the wounded portion of the stem. Secure this in place with wire or a stone. Within about a month or two, new roots should form; however, it’s better to allow the stem to remain intact until spring and then remove it from the mother plant. You can then transplant your trumpet vine in its new location.
Propagating Trumpet Vine Roots or Suckers
Trumpet vine can be propagated by digging up the roots (suckers or shoots) as well and then replanting these in containers or other areas of the garden. This is normally done in late winter or early spring. Pieces of root should be about 3 to 4 inches (7.5 to 10 cm.) long. Plant them just beneath the soil and keep them moist. Within a few weeks or a month, new growth should begin to develop.