A: Once the peonies are dormant and cut to the ground, they should be safe from any damage by Roundup (glyphosate) — the most popular kill-everything-green herbicide.

How do you kill weeds around peonies?

Hand weed the area first and never spray herbicides near peony plant crowns or root zones. If you need extra help controlling weeds, you can apply a pre-emergent herbicide, like Preen, around peony plants after hand weeding, but do this only when peony shoots are at least 6 inches (15 cm.) high.

Will Roundup kill spring bulbs?

When They’re Not Blooming When you notice weeds in your daffodil bed after the foliage withers and dies, it’s safe to spray the entire area. Roundup doesn’t leach through the soil, so it won’t hurt the bulbs if there are no living leaves above ground to absorb it.