Do they prefer acidic soil? I have some peat I could work in.

In the photo they are not getting full sun because of the shade from a tree. How much of the day is the tree casting a shadow?

First, I apologize for the miserable picture.

In the summer months, they get sun from sunrise to maybe 2-3 o’clock. The left one gets shade a little sooner than that. They are getting less sun now, of course. One bush has a few buds on it.

There was a third raph (a mini variety) which was sulking as well. I dug it up, put in a pot in a part sun location and it has started to grow.

These are commonly planted in hell strips and parking lots. Hard to believe that heat would be a problem.