Trishfar,
What is barch?

To butterfly4u
Barch is finely chopped wood chips used as a mulch. When I bought the shrub it recommended I top dress it with 3" of mulch

Trishfar,
Oh, ok, I'm sorry, mulch.
Don't put the mulch within 4 inches of the bottom of the plant.
If you have it anywhere near the main stem, get if off.
Mulch will rot in hot weather and the rain your speaking of is not helping with the rot situation.
Also, believe it or not, 3 inches of mulch too close to the plant can actually prevent the plant from getting enough water to the roots nice and deep where it needs it.
I hate mulching hibs, I just put 1 inch around the outside of the plant in the summer for my hibs in the ground.
If your hib is in a pot, take the mulch out.
You won't need it if you water everyday.
In the heat, 3 inches of mulch can really mess up your hibs.
My hibs are gorgeous and growing so big I will have severe pruning to do to bring them indoors for the winter.
If the hib perks up after removing most of the mulch, that is what it was. If not, you may have to acidify the soil for the plant which can easily be done by adding 1 cup of white distilled vinegar to 1 gallon of water and gently pouring this mixture over the roots only (don't get on the leaves), this works great.
FIrst try the mulch idea. GOod luck!
I know how much you like your plant, I love them.
Let me know how it goes.

Thanks I'll try it and let you know

Tried vinegar and water still loosing leaves. Also removed all barch and still same problem.
Any other suggestions
Thanks
Pat

Pat,
H. rosa-sinensis will get yellow leaves for various reasons including too much water, not enough water, not enough fertilizer (especially nitrogen), too much fertilizer, and excessive heat. I have several of them and with the current heat wave down here, one of them has dropped lots of yellow leaves. They are full-sun tropicals but can use a shady break from excessive blasting afternoon sun. If you haven't fertilized it lately, give it a well balanced fertilizer like a 7-7-7 or one with the middle number a bit lower than the other two. That's phosphorus and it hangs around for a long time in soil so it is easy to overdo it. It's good to fertilize hibs often and at a low strength...they are heavy feeders. About an inch of rain per week is a comfortable amount for them. Good luck...let me know if this helps.
PS...they are tropicals so they will need to be brought inside in zone 4 for the winter.

Trishfar,
How is your Hib?
Is it still loosing leaves?