Intrusive Japanese Knotweed
I have Japanese Knotweed - Polygonum Mutiflora all over one side of my yard. I am looking for a non-toxic herbicide. So far, I have cut the tops off and dumped bleach, ammonia (not mixed), salt water, and vinegar into the hollow stems. I then used a skewer to make a hole into the lower chambers. None of the trials are a total failure at killing the 45 foot roots, but none are a complete success either. I do not want to use a Round-up type product in my yard. Got any ideas?
Submitted by BHGPhotoContest

Chlorine bleach and ammonia are far more toxic in the garden than a broadleaf herbicide with Trimec. All of the remedies you mention--bleach, ammonia, salt, and vinegar--remain in the soil and can damage not only the weeds you're targeting, but all other plants that you'll ever try to grow on the site. On the other hand, products like Roundup are designed to become inert when they contact soil. That means they only harm the plants they touch. I know you'd like to stay away from a chemical herbicide, but you'll be much better off with a broadleaf weed killer (look for one with Trimec) than any of the alarming remedies you mentioned. Unlike Roundup, broadleaf weed killers target only broadleaf weeds and won't harm your turf grass.

Answered by BHGgardenEditors