The best homemade deer repellent for plants is a mixture of garlic, eggs, and water. This concoction works by utilizing the strong smell of garlic, which deer find highly unpleasant. To make the repellent, you can crush several garlic cloves and mix them with beaten eggs and water. After straining the mixture overnight, it can be sprayed onto plants to deter deer from feeding on them. This homemade repellent is cost-effective and safe for both plants and the environment.