I was going to suggest the Soil and Compost Forum, until I noticed that you have already posted there as well. But since this is the Bean Forum, I would suggest that you grow purple and yellow pole beans in your sharing garden; they are highly visible, bear over a long period, and nearly everyone enjoys fresh beans.

Sounds great. I think you'll get plenty of good answers in the Soil Forum.

Consider to arrange the flowers in such a way that they might be companion plants for the veggies that you'll be growing.

If you add trellis for the beans and other vining plants, then that can also be a shade for some plants that don't like as much hot sun.