To successfully buy and plant crocus bulbs (technically known as ), you should focus on purchasing them during late summer or early fall (September through November) to ensure they are in the ground before it freezes. High-quality corms should be large and firm, as larger ones store more energy for stronger blooms. For a high-impact display, aim to buy at least 100 bulbs per square meter or plant them in "drifts" of 20 to 30 together. When and Where to Buy Go to product viewer dialog for this item. Crocus Vernus Jeanne d'Arc Giant Dutch