Greens grow year-round in areas with mild summers and winters, such as the West Coast. For most other areas, spring and fall are the best times to grow greens. Greens can be sown directly in the garden starting in spring and, in cool areas, planted throughout the summer until September. If you want to get a jump on the season, start seeds four to six weeks before the last frost date in your area so they can be planted two to three weeks later.