If you have moles that visit your garden then you are sure to have some problems — they dig holes, mess up flower beds, and damage plant roots. If you don’t want to go the route of poison or pest control to take care of mole holes in your yard, a better way to handle the situation is to discourage these tunnel-digging mammals from visiting your garden in the first place, and the humble onion might be the repellent you need.
The assumption that onions make an effective mole repellent is mostly anecdotal — a tip passed down through generations of amateur gardeners. In a Houzz forum, one participant noted, “I don’t remember seeing them tunnel through my garlic or onions over the years.” What people believe keeps moles away is the strong scent of the onion paired with the excellent sense of smell of the burrowing pest in question. Onions — and, in fact, all plants in the allium family — contain volatile sulfur compounds and emit a pungent scent when damaged, so it’s not a stretch to assume they’re hyper-sensitive to unpleasant smells like the onion.
Onions as mole control
The go-to method for onion mole repellent is planting them along the borders of beds or around plants you wish to keep safe. The idea is that you create a barrier of scent the moles are unwilling to cross. Another method that may be effective is to sow garlic bulbs an inch or so below the surface of newly planted beds.
Other gardeners suggest pickled rather than fresh onions. In a Gardeners’ World Magazine forum, one member expands on the method, advising home gardeners to “push two pickled onions down the hole until you hit the horizontal part of the tunnel.” The smell encourages the moles to leave. Other plants in this family might also help to get rid of moles in your backyard and garden. Follow the methods above, but swap out the onions for garlic, chives, leeks, or shallots. Just remember that all plants in the allium species are toxic to cats, dogs, livestock, and possibly other mammals, so keep pets and farm animals away from areas treated with the repellent.
