They bloom on new growth so the more new growth you get during the spring, the more potential for bloom. These will bloom all the way until frost so you'll have plenty of time to see more blooms! My mother's inground ones - some there for almost 40 years, tend to start off with one or two blooms and gradually pick up as the summer goes into fall.

I can "always" count on you Jenny. Thanks soooo much. I've noticed some aphids on my ROS and sprayed them off with water and dish detergent. Mostly they are all gone now. I've also noticed I have several new buds so perhaps I need to be a little more patient. I'll bet your mother's Rose of Sharon is beautiful. You must take after her for your gardening "know-how"

Hi, I have lots of ROS in pots because they bloom in the summer and it gets so hot here that you have to choose things that like it hot. I find they like their soil to be very warm. They also bloom in flushes. I got a bluebird this year and have had very little luck with it--but I think it will be better next year. The very best one I have found for my pots is the one that has large all white flowers (not with the red throats) It really is a bloomer. Also the double "red" (really mauve) are good bloomers. They will all bloom if it gets hot enough though.
Some varieties are much later than others and they all pick up the later in the summer it gets. I just fertilize them with bloom fertilizer according to directions and it seems to work well. They like it rather dry so I use Al's suggestions for a fast draining potting soil, or you could use a wick--if their roots are wet they take longer to bloom. I think more people ought to try them in pots in the hot zones--they look great.
Betsy

Hi Westview, thank you for your help. Yes, mine is a bluebird too. Very pretty. Well, I ended up with more aphids than blooms. I tried hard to get rid of them and they just got more plentiful and I gave up trying when the leaves started to get crispy and dry up. Sometimes I think I'm just not a very good gardener.