Hibiscus syriacus 'Blue Satin'

what conditions does this need Rk ? i have one here that hasnt flowered in three or four years

They like full sun but I have another in mostly shade that has also flowered well. How big is it? I cut them back about halfway in Spring (while leaves are developing or even after) which encourages strong growth. They flower on new growth so cutting them back will make them flower better too.

its around 24 inches high?? it hasnt flowered in all the time i have had it ~ i bought it for a present for the mother in law, she had a sunny garden. she said she didnt like it cos it didnt flower enough and gave it back ~ can you believe that???

ah, i didnt cut it back, thanks Rk ~ i will do that.

If it's only 24 inches high that might be part of the reason too. A lot of them we grew at the nursery didn't flower much at that size. They are pretty reliable flowering plants if they are growing well, it might just need a little more time. The one in the picture was only 12 inches high at the beginning of this season and is probably twice that now. It only had two flowers last year but it had been very dry when I got it.

I think it was in flower when we bought it though? It's in a dryish spot now, is that not good?

If you see it wilting a lot it might be. I have a large hibiscus planted by my door that gets quite a bit of shade and is in a dry spot. It never flowered well until I started cutting it back hard. From what I've seen, they seem to tolerate being dry much better than a lot of other flowering shrubs but too dry for any plant can affect growth and flowering.
I potted dozens of plants this Spring to prepare for moving this summer and used a good potting mix for all of them and have stayed on top of watering,fertilizing and pruning. Giving them extra attention like that has made almost every one of them grow and flower better. When hibiscus is happy it is a fast-growing plant and will flower well on the new growth it makes. It might be too late this season to rejuvenate it by cutting it back (cut as much as the top 1/3-1/2) but you could try. Otherwise, try it in Spring and if it gets dry give it a good soaking once in a while. They also respond well to fertilizer, I used miracle-gro when it started pushing new growth and got good results.

Thanks again Rk, I shall certainly try that, I haven't noticed it wilting at all and I think there is still some time left for growth, as I haven't anything to lose I shall cut it back a little and give it some sort of feed. Thank you.