I started my tuberous begonias inside in small pots about 3 weeks ago, in a sunny window. They are growing pretty slowly. A few have actual leaves but they are still small and folded. Some have sprouts hardly bigger than 3 weeks ago. The dahlias, by contrast, are 8 inches tall.

I was thinking about putting them outside on my deck or black asphalt driveway but am not sure how much cold they can tolerate. At what temp would they benefit from more sun? For example, should I put them out when it will be over 60 degrees F? Bring them in at night when it dips below?