Border columns made with wood post placed in flower beds close the walk are beautiful, add lots of interest to the garden Place a big container of pretty flowers on top of the post. maybe could use pvc pipes w flower basket set on top?
Solar Garden border at Great Dixter, a house in Northiam, East Sussex, England - photo by Jonathan Buckley; Allium hollandicum ‘Purple Sensation’ with Campanula patula and Erysimum allionii in the Solar garden at Great Dixter
hydrangea and wisteria - both have varied flower colors. Both are also seen in Old Southern landscapes. Hydrangea like rich damp soil with filtered sun. Wisteria will seek out light and do well in full sun.
I love colorful foliage plants. They also are perennials and would come up here after year. I think this is a beautiful idea to plant these hosta type plants under a tree with all their different colors