A barrier of poisonous plants deters voles

Voles, unfortunately, moved into my garden about 15 years ago. Most of my hostas were devoured before I realized what was going on. My pachy­sandra was riddled with tunnels, and the voles even went so far as to take out a cherry laurel and a young Japanese maple. A solution that I have had success with is to bring in plants known to be poisonous, such as hellebores (Helleborus  spp. and cvs., USDA Har­diness Zones 4–9), monkshood (Aconitum spp. and cvs., Zones 3–8), bleeding heart (Dicentra  spp. and cvs., Zones 3–9), lily-of-the-valley ( Convallaria majalis spp. and cvs., Zones 2–7), mayapple (Podophyllum  spp., Zones 3–9), and daffodils (Narcissus  spp. and cvs., Zones 3–9). I plant these in drifts to encircle areas planted with the tasty, more vulnerable plants. Also, when I cut back spent foliage from the toxic plants, I mix the cuttings with old leaves from the woods, chop it all together using my lawn mower, and dig it into new beds or use it as light mulch.
—Mary Bowe, Richboro, Pennsylvania