Winter temps came back for a visit the last few days, but it's looking like spring again today. Doesn't look like it was cold enough to hurt anything, but we did have a shallow blanket of snow yesterday morning. Seeing all the sprouts has had me browsing my favorite Cubits and forums too, it's great to share the excitement!
Polly, I forgot to mention earlier, something that I think may be preferential for Rex Begonias. The year than mine were happiest was the year I had them potted in homemade potting compost. It was made mostly of mulched leaf mold that had aged for about 6 months and was full of worm castings. It only lasted for the season, as it compressed and decreased in volume by fall, but those Begonias loved it. The next spring I repotted them in a mix of Miracle Gro potting soil and fine textured mulch and they were pretty happy with that, but when I potted them into pure MG potting soil they were not nearly as happy. I have a feeling they like airy, well drained medium, that can still hold moisture well.