STORE. Chill vegetables, leafy greens, and herbs in an airtight container lined with paper towels. Whenever the paper is wet, replace (usually every other day or so). Chill asparagus and edible flowers upright, cut ends submerged in water (as if in a vase), uncovered, for up to 3 days.
WASH. Excessive water causes speedy spoilage and can damage delicate leaves, so try to avoid washing delicate herbs and flowers, and wash everything else the day you plan to make a salad. For greens, trim and pluck off any wilted or tough outer leaves. Fill a large bowl filled with cold water (I often add an ice cube). Add the greens to the bowl, but not so many that they’re crowded. Swish with your hands and let debris sink to the bottom. Lift greens into a colander or spinner and dump water; repeat until no sand remains.
DRY. Use a salad spinner or spread wet greens on a kitchen towel, top with paper towels, and loosely roll. Chill up to 12 hours.