Cilantro can be refrigerated for up to two weeks using this method tested by ATCO Blue Flame Kitchen.
Trim off the ends of stems of an unwashed bunch of cilantro. Remove and discard any withered or yellow leaves. Place the stems in a jar or glass filled with 1 - 2 inches (2.5 - 5 cm) of water. Cover jar loosely with a plastic bag, preferably a vegetable storage bag; refrigerate. Change the water every 2 - 3 days.