Cut stalks of cilantro from your garden or purchase a bunch of cilantro from the produce section of your grocery store. If you intend to store your cilantro rather than using it all immediately, be sure to keep the leaves on the stems rather than plucking the individual leaves from the plant.
Snip the ends off the cilantro stems with a pair of kitchen scissors. As is true of fresh-cut flowers, cutting the stems will help the cilantro to take up water which will make its freshness last.
Fill a small jar or drinking glass with several inches of fresh water. The jar or glass does not need to be large but it should be tall enough to support your bunch of cilantro.
Place the cilantro stems into the water in the jar. Check that the water level in the jar is not so high that it soaks the leaves, or your cilantro may begin to wilt and rot. If the leaves of your cilantro are already damp, or if you have chosen to rinse it, pat the leaves dry with a paper towel before putting it into the jar.
Put the jar of cilantro into the refrigerator and cover it loosely with a plastic bag. Cilantro does best in cooler temperatures, so if you notice your cilantro beginning to wilt after a few days, lower the temperature in your refrigerator by a few degrees.
Check the water in the jar every few days. If it becomes discolored, replace it with fresh water. Keep your cilantro in the refrigerator for up to two weeks.