Wash garden lettuces or other salad greens well, but do not let them soak in water. This can soften the leaves and cause them to spoil quicker.  Dry the greens thoroughly, either by blotting with paper towels or with a salad spinner.

They can be stored in a plastic bag in the refrigerator, but put a damp paper towel into the bag before closing. Otherwise, place a paper towel in the bottom of a plastic container. Put in the salad greens, then place a damp paper towel over the lettuce. Cover with an airtight lid.

Watercress can be stored by sticking the stems in a glass of water and placing a plastic bag over the leaves. Wild greens should be used immediately.  Lettuce will last 3-5 days depending on the variety. Romaine will keep longer. Tear or cut lettuces and greens before adding them to salads. Cut strong-tasting wild greens into smaller pieces than you would for lettuces to distribute their flavors.