Answer: As you've discovered, Round-Up is a non-selective vegetation killer. If you spot spray weeds, it will remain on the weed and travel down to kill the roots. It typically remains in the roots of the targeted weed rather than traveling through the soil. If you sprayed the entire area around your perennials, the Round-Up will translocate into the soil and be taken up by the roots as it is carried by water. Once it is in the root system it will remain until it biodegrades. How much damage it can cause remains to be seen. There's no way to get it out of the root systems. The Round-Up that was not taken up by plant roots will biodegrade in slightly over 2 weeks when exposed to sunlight and fresh air. I would just wait and see what happens with your perennials. They may recover and if so you can simply prune off the dead plant parts. Good luck with your plants!
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