Thank you both for your replies. (I especially like the picture of the dogs!) My potted wheatgrass is outdoors and because it's been raining lately, we haven't watered it. Before that, I think my husband was watering it every other day or maybe every three days. I'm not sure because I don't always notice. I'm wondering if maybe it's the end of its life cycle because we bought it matured, thick, and very lush already from a store and then we put it in a large pot so it could have breathing room and it's been outside for over a month now in mostly direct sunlight except for maybe 4 hours a day. It began yellowing only over the last two weeks and I just don't know what to do for the poor thing. Thanks again to both of you for your prompt and informative replies.