When purchasing asparagus, look for straight, bright green spears that are firm and crisp. Tips should be tightly closed and dry, with stem ends moist. Asparagus stalks vary in thickness; whether you choose thick or thin is a matter of personal preference. Thickness does not correspond to sweetness or quality. Purchase spears of uniform thickness to ensure even cooking.
Refrigerate asparagus, set upright if possible, in a container holding an inch of water; cover the container loosely with a plastic bag or plastic wrap. Or, wrap stem ends in wet paper towels and place the asparagus in a plastic bag in the refrigerator.