Moles are both useful and a pest depending on how many there are in one area. When they are controlled they can serve to protect the area from grubs and smaller pests. When they are uncontrolled they can cause damage to lawns, gardens and plant roots. When a mole digs under or through a root system it can cause exposure of the roots to air and sun, thereby drying them out and killing the plant. Creating a natural homemade mole repellent is a safe and environmentally friendly way to encourage the moles to move elsewhere.
There are two types of natural mole repellents – liquid and horticultural. Liquid repellent is applied as a spray. There can be various types of each depending on the preference, although combinations of the various types can be applied to provide best results. Horticultural methods include the use of various plants known to deter by smell and taste, or poison moles when ingested.
Different plants can act to deter moles naturally. Plants such as onion, garlic, chives or others with strong smells and taste are a deterrent to moles. Other plants that may be effective are Allium giganteum and the castor bean plant; these plants are poisonous to moles. There is also a plant called the Mole Plant, which is also a mole repellent with a milky substance that flows when the large leaves or stems are broken open – similar to milk weed. Moles find this plant undigestible. Missouri State University states that in order for plant repellent to be effective it must be used as a group of plants set out as a ring or line around the protected area.
Liquid formulas are commonly used as a homemade mole repellent. One formulation includes castor oil and either a mix of red pepper or soap. Anne Lovejoy, gardening author, suggests using two parts castor oil, one part dish soap, then mixing two tablespoons of the blend to one gallon of water. Michigan State University lists a recipe of 1/4 cup castor oil, 2 tablespoons dish detergent and 6 tablespoons of water. Put the mixture in a spray bottle or hose attachment and apply in spring and autumn. Liquid sprays are best for open spaces where mole hills are evident.
Castor bean plants are poisonous to both moles and humans when ingested. While Michigan State University recognizes the use of homemade formulas it advises that these may have a more limited duration than expected.
There are commercial versions of the liquid sprays, as well as commercial growers who sell plants as mole repellents. Using the recipes stated or growing your own plants from seed or sprout can yield the same or similar results for much less cost.
Michigan State University - https://web1.msue.msu.edu/imp/modwl/11209807.html
Missouri State University - https://extension.missouri.edu/publications/DisplayPub.aspx?P=g9440
Ann Lovejoy - https://www.seattlepi.com/nwgardens/305585_lovejoy03.html
Image Source: Sergey Yeliseev