and I mean total newbie on Peonies!

Do they spread or reseed at all? What I need is I'm thinking of totally redoing a small garden bed for next spring that is only about 6 ft wide by 4 ft deep and was thinking of just filling it with peonies. The area is on the north side of my house and gets mostly sun. Of course, I would imagine that I would want ones that bloom at different times, early, mid, and late?

Do they flop?

How many for the small bed? What is the spacing needed between each?

When is a great time to plant them in my zone 5b Ohio?

I'm also looking for fragrance too, but not worried about colors.

Any info you can give me would help! :)

Right now the bed has in it, one daylily, one small hydrangea which I'm very dissatisfied with Blue Heaven gets too much sun there, and loads of reseeded Purple Dome Asters, which I am going to shovel prune soon as most of the year they are unimpressively green lol.