I'm reclaiming a flower bed built 6 years ago. It was a foot of mushroom compost double dug into a foot of red clay under pine trees. A shovel just sinks to the hilt. This may be TOO MUCH drainage as a handful is all grit without a lot of actual soil to "glue" it together..
Woods vines took it over the first spring and that's the only thing that survived. I didn't have a weedeater then, but have a good one now, and I'm not afraid to use it. I pulled out, raked out, all the vines over the last 2 days.
The bed gets 3 hours of late morning/noon sun and then dappled shade and deeper shade the rest of the day. And the bed is 12' deep and 35' left to right with 75yo pine trees over hanging on the west side with baby hardwoods as a sun break between them.
I'm thinking of "planting" in clay chimney flues buried mostly in the bed. They are 8-12" across, and I could weedeat those pesky determined woods vines against them without damaging young plants inside them. Water hoses reach this bed so city water is available as needed.
I'll plant in a landscape mix which is 1/3 aged cow manure, 1/3 mushroom compost, 1/3 red clay. I can add nothing or spagham peat moss or pine bark fines as needed -- have lots and lots of those... I'm thinking the landscape mix alone should be fine since each plant will be elevated in a flue and can't help but drain.
I'm not so sure it would be so perfect for hostas if it's still getting sun at noon. In your zone, it might need some additional shade to prevent frying the hostas. But if you choose the plants well, it should work well.
My dear uncle passed away last year. He was a musician and a college music professor. He could play many instruments including the viola. Occasionally he would bring it up north and play for us when he would visit and the joke was that he brought his friend "Viola" along with his wife Sue. Your little picture made me think of him this morning. Thanks!
My uncle spent most of his working life down in the Baltimore area. He graduated from Peabody Conservatory and he played piano, guitar, viola, trombone, I think, and probably other instruments, I am not sure. He taught and then he was the Dean of the Music Department from what was Western Maryland University. I think it has a new name now. He was a founding member of the Baltimore Comic Opera Company and he had a regular gig playing in the band when the circus came to town. He gave classes and workshops when he retired down in Florida and both his wives were musical. My Aunt Ginny, who passed before he did, sang and my Aunt Sue played and taught piano. He and I always argued about opera. He thought it should be all sung in English here and I argued for the original languages. He also knew the words and music to a million funny songs. We miss him. And Viola.