Answer: Hmmm... you could end up mixing a nasty combination that might remain in the soil for a long time. I don't think I'd mix the two products together. Not knowing what they might contain (you didn't provide brand names), but general knowledge indicates they probably have the same ingredients - 2,4-D, glyphosate and/or Triethylamine Salt - 8. Instead of making your own herbicide cocktail why not simply use a product labeled for use against weeds? Round Up does a good job of killing both the tops and the roots of the weeds, it does not translocate into the soil, and it biodegrades in the presence of sunlight and fresh air. Be sure to apply according to label directions because it will kill anything it contacts. To keep weed seeds from sprouting in the bed you can apply a corn gluten meal based pre emergent. (Preen or Casoron are examples). Good luck with your weed eradication project.
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