Is there anything we can apply to our perennial beds that will kill grass and weeds without harming the good plants?
Yes! Don’t forget the pre emergent herbicides to help stop the seeds from growing. Preen and Organic Preen (Corn Gluten Meal) work nicely (read the labels for any restrictions). For those grasses and weeds that are growing, spot treat with Roundup, Kleenup or Espoma’s 4n1 Weed killer (all natural) without spraying the desirable plant’s foliage. And for the weedy grasses only, try Fertilome’s ‘Over the Top’ or Bonide’s ‘Grass Beater’ which can be sprayed over the top of many desirable plants without harming them (again read the label before using).