Ask Mr. Smarty Plants

You have several major problems, as we are sure you know, and not much of any way of solving them with plants, which is what Mr. Smarty Plants tries to do. Of course, if gardeners all listened to Mr. Smarty Plants in the beginning, there would be no non-native invasives such as Firmiana simplex (Chinese Parasol), Melia azedarach (Chinaberry), Lonicera japonica (Japanese honeysuckle), or Ligustrum japonicum ( privet) being planted in the Austin area, but obviously there are. Each link above will take you to a website that tells why these plants are so undesirable.

You are probably not going to be able to convince your neighbor to control or remove his invasive plants. Even if the homeowner went out today and cut down all the alien invasives, their seeds and roots would perpetuate their existence. We did a little research on Root Barrier instructions, most of which were advertisements, but this one seems to have some good advice.

About all you can do is fight a defensive action. Putting down a root barrier on your property line, cutting off any roots coming onto your property and perhaps painting the stubs with an herbicide might slow down the progress of those roots. If you choose the cutting and herbicide route, use an undiluted solution and a small disposable sponge paintbrush, painting the cut surface immediately so the herbicide will be absorbed before the root starts healing over to protect itself. This is not going to be sufficient to kill the neighbor's tree, but might keep that particular root from regenerating into your space. When you have dug out a trench and treated such roots as you can, then you can get the root barrier in. We have no personal experience with this, so you might want to get professional help.

Beyond that physical barrier, you will have to be vigilant about suckers and seedlings in your garden, removing them by pulling, cutting or mowing as quickly as possible. Our hope is that other gardeners planning their landscaping will read this and understand the damage they can do to the environment and to neighborhood relations by putting in plants that are non-native, invasive and totally undesirable. You and other interested gardeners should read our How-To Article When is a Guest a Pest? The best way to control invasive plants is to never plant them.