The best skunk repellent is a light. Skunks are nocturnal and their eyes are very light sensitive. A bright light or a motion sensor flood light will scare skunks away.
Most animals, including skunks, dislike the smell of citrus fruits. Place orange or lemon peels around the yard as a natural skunk repellent.
Spray a mixture of castor oil and dish-washing detergent diluted in water. Skunks find the smell offensive. Spray the area at night when the skunk is away foraging.
If the skunks are in a smaller garden patch, put bars of strong-smelling soap or a room deodorizer near your garden. Ironically, skunks hate strong scents.