What is the best plant to deter snakes?
Marigolds.... Mother-in-Law's Tongue. ... West Indian Lemongrass. ... Onion & Garlic.... However, no one plant effectively repels snakes and plants need to planted in conjunction with each other for effectively repelling them. Bear in mind nothing is totally effective when a snake is hungry or angry.
Don't give them places to hide, tall grass, dense planting etc. I have heard mothballs work, but they smell hideous and deter other animal as well, maybe ones you want.