Hydrangea would be my suggestion but idk how they do in akaline soil so someone here will likely be able to tell you more on that...as far as the variety, I have the Quick Fire hydrangea and I love it...blooms all season long changing from bringing white to a dusty rose pink. They get grow fairly quick and are pretty maintenance free for me so maybe look into one of those?

Does the quickfire grow to 6' +? Thought it was a smaller variety... what about width on that? I have a limelight that is performing really well but in part sun (only 3 hours max of direct then some dappled then full shade).. I thought about that but I wonder if there's too much sun for it. The spot gets 9+ hours

thanks

My unpruned Quickfire at 8 years old is between 6' and 7' tall and wide. It grew to about 5' quickly, in perhaps 4 or 5 years from a rooted cutting, and since then has been slower, but still getting a bit taller. Little QF is smaller.

My H. paniculata cultivars grow in literally all day sun, from when the sun comes over the top of trees a ways to the east until it disappears behind the trees to the west. In midsummer this is most likely something like 14 hours of sun.

My quick fire got to be about 5' and I've had it for like 3 years now..maybe 4? It does look to be growing still because there are some branches that seem to be extending upward from the main 'bushel' so it's looking like it's about to have a growth spurt again. I don't think it will get much bigger so probably more like 5'-6' I'd assume will be the max..but again, I can't say 100%. I will say it seemed to grow rather quickly so that's a plus.