The peak months for buying asparagus are April and May. When buying, look for firm, straight, uniform-size spears. The tips should be closed with crisp stalks. It's best to use asparagus within a few days of purchase. For a little longer storage, place bundled stalks upright in a bowl filled with 1 inch of water; refrigerate. Or wrap the cut ends in moist paper towels. Cover the towel with plastic wrap; refrigerate. To clean, soak asparagus in cold water. Cut or snap off the tough white portion.