Removing 20-year-old Trumpet Vine Is Not Easy!

Q. I have 20 year old trumpet vines which I have been trying to remove to establish a new garden. The vines have been dug out as best as possible but as I try to establish a new garden I find shoots coming up from roots so deep I simply cannot remove them. Is there a way to completely eliminate the deepest roots from the trumpet vines without poisoning the ground?

Trumpet vine or trumpet creeper growing in someone's property and draping over the wall

A. Trumpet vine is considered "invasive" in some parts of the country. This is usually in places where there is enough rainfall to support their growth without irrigation.Needs water to survive. It is very unlikely to survive in the hot Mojave Desert without irrigation. However it could become established along Lake Mead, the Colorado River, Virgin River, Warm Springs area and along desert washes.

Look here to check on it's invasiveness

The only "organic" method of killing trumpet vine roots is to totally cut off the top of the plant and force it to "sprout" wherever it has spread underground. As this new growth emerges, you will physically remove it with a shovel or hoe. By doing this repeatedly and as soon as new growth emerges, you will eventually exhaust the root system.

As you have already guessed, this will require a lot of diligence on your part. My experience with plants such as these, exhausting the root system by physically removing new growth can take you two to three years.

Another method is to leave the "mother plant" and dig up suckers as they emerge. This helps direct the growth to the mother plant and suppresses the development of sucker growth in new areas. The plant will slowly “give up” growing into new areas as it ages.

There are chemicals that you can use to help you kill the roots. None of them will contaminate the soil for any length of time. They ARE chemicals so if these chemicals land on the soil surface there will be residue left behind but it would be minimal.

If you are careful in applying these chemicals, none of these need to reach the soil. This method relies on applying or dabbing an herbicide on fresh cuts made to the plant. The plant is cut back and herbicides are applied to these fresh cuts with a paintbrush. This technique relies on herbicides to replace a shovel and a hoe.

Herbicides used for this include “dandelion killers” that contain dicamba or triclopyr. You will have to look at the ingredients on the label and the label should state that they can be used for this purpose. The label may call them "dandelion killer", "brush killer", etc. 

Roundup is also used for this job and applied in the same manner. Follow the same dilution that is recommended on the label as a spray. Repeat applications will be necessary because the plant will respond by sending up new growth in different locations. So be prepared to follow up by cutting back in growth and reapplying the chemicals.