Berries rot and get moldy very quickly. To keep berries fresh longer and deter the growth mold, rinse your berries in a mild vinegar solution as soon as you get them. Put your berries in a mixture of 1 part vinegar and 3 parts cold water. Dry the berries on towels and store them in an airtight container with a paper towel in the bottom. Your berries will stay fresh much longer.