Vegetable soup with barley

Yesterday was cold and rainy. We even had sleet for a short time. Most unusual. The cold has persisted into this morning: it's below freezing out now.

I made soup last night, with barley and mushrooms, garlic and onion, a handful of baby carrots and a couple stalks of the celery we bought to make stuffing for Thanksgiving. Half the bunch of celery is left, and it's going limp. I wonder what to do with it besides throwing it away.

I didn't time the soup-making very well. I put the celery in too early and it got overcooked, and a lot of the liquid boiled away, so there's not as much broth as I'd like. Here's the order in which I'd do things next time:
( for future reference )