This one is easy, tea leaves are excellent for plants. Simply empty the contents into your garden for use as compost. Rather than rushing out into the garden with every used bag, it’s a good idea to empty the tea bags as you use them into a container so you can build up a batch of tea leaves. But don’t leave it too long before emptying.Fertilize roses: Spread used tea leaves around rosebushes, then add mulch and water. The tannic acid and other nutrients will benefit the plants.