Please do not wash the coriander. Once you wash them, they will not keep well in the fridge anymore. Only wash them when you are ready to use them in your recipes.

Discard any coriander leaves that do not look good. Trim off excess stem if needed so they fit in your jar, glass or container. Fill up with normal tap water (don't have to be cold as the water will turn cold in the fridge) to make sure they are submerged in the water.

Cover the leaves and the top of the glass loosely with a plastic bag or a ziplock bag and store in the fridge.

Dump the water out every day or two days and fill up with clean water again and store in the fridge. I am able to store the coriander in the fridge this way for about up to one week and the coriander stays crisp. At day 8, few coriander leaves started to get a bit brown but still crisp.