I live in the country side in Northeastern Pa. and derr are always in my garden. The best things i have found to keep them away are, tabasco sauce and human hair.
I put the tabasco sauce in a spray bottle and spray the plants with it at night just before dark. I, also, go to my local barber and get all the hair he/she has cut that day and put it around the outside of the garden. So far, knock on wood, it has worked and i have been doing this four 10 years now.