Ask Mr. Smarty Plants

Mahonia repens (creeping barberry) is native to Colorado, and is a stoloniferous, sprawling evergreen. It is widely praised as a low groundcover with fruit attractive to birds, and listed as a non-invasive alternative to several invasive plants. However, "invasive" is in the eye of the beholder, and we can see how having it in the wrong place in your garden could be a problem. The fact that it is stoloniferous means that it spreads like some grasses, with below-ground root systems spreading it very efficiently.

To begin, and to get a better feel for the situation, start pruning away and discarding the cuttings in such a way that no berries left on the cuttings will get a chance to propagate themselves. You're clearing the area so you can find where the plant comes up from the root. When you find that, cut it through as near to the ground as you can. Paint the newly-cut surface with an appropriate herbicide, at nearly full strength, with a disposable sponge paintbrush, within 5 minutes. The herbicide must go on the cut area quickly before it begins to "heal" itself, thus preventing the herbicide from getting down to the roots. Now, because it is stoloniferous, you still have to deal with those roots. That plant is going to be trying to survive, no matter what you do, so the more damage you can do to the roots, the better. Drive a sharp shovel into the ground and cut them, expose them and prune them, or whatever method works best for you. Grubbing out the stump and discarding it will also effectively starve any remaining roots. You will have to continue to be alert; the plant propagates by roots sending out new little plants and by seeds that may have fallen months before. Just keep pulling them out until the shrub is exhausted. The best time to do this is in the Summer, when the heat and the sun will help in your destruction.

We didn't say it was going to be easy.