How to Grow Perennial Vegetables:Perennial vegetables are a joy to grow. Whereas traditional vegetable plots are largely made up of short lived, annual vegetable plants, perennials are edible plants that live longer than three years. Grown as permaculture plants, they take up less of your time and effort than annual vegetables, and extend the harvesting season avoiding the hungry gap between the end of the winter harvest and the start of the summer harvest of annual vegetables.