That all depends on where you live and what you want to plant. For vegetables that need warm weather (beans, tomatoes, corn) you must wait until all danger of frost has passed - usually in June or the end of May for most parts of the USA. Some cool season veggies (peas, lettuce, beets) like to go into the ground in early spring, when you see daffodils in bloom. Trees, shrubs and hardy perennials can be planted anytime you see them for sale potted up at local nurseries. Your local nursery professional or Master Gardener group will have the most detailed information about growing and planting specifics for your part of the country. Welcome to Gardening, Marianne Binetti