I don't think you have to move right to questioning his competence. I would check first what assumptions each of you is operating under. If you have given him instructions to produce a certain kind of environment in the yard, shade may be an essential part of that and perhaps he can't produce any other source of shade in the short term and is concerned you'll not be happy with the outcome if there isn't enough shade. Or something. He may also be making some assumptions about how much you want to water your plants. I de-shaded the north side of my house with the removal of a tree and it does get sunny as the sun veers around in the afternoon. New trees are just growing in enough to make an impact 4 years later. If there is a chance you will be removing the big tree at some point within 5 years, the pot is a very good idea for another reason - you'll have to get the little maple out of the way of falling tree parts. They do grow well in pots, especially if the pots are big enough. KarinL

I had hosta, epimedium, korean bleeding hearts (dicentra exemia), hakonachloa aureola, Japanese painted fern, and a bunch of other stuff under my Bloodgood. It was very shady as the neighbor had big trees and there was a 5' fence just on the other side. I also put a goldfish pond underneath. Unfotunately, it caught that blight and begin to die a slow death...Here's what my garden looked like the last year I was there (2004). You can look at other items in this album, as there is a garden bed planted underneath a Norway maple and along the fence was shaded by the Norway and the neighbor's oak trees (all mature). Here is a link that might be useful: My bed under bloodgood

I would not recommend it. Raised beds smother a tree's roots which are at the surface and could eventually endanger the tree. My neighbor did this and lived to regret it. Not to mention large trees suck all the moisture away from the plants. Sometimes the tree roots will grow right up into the bed. If this is something you really want, I would dig small holes amongst the roots and plant the plants directly in the ground instead. Amend the pockets of soil and be diligent about watering. Rain will not reach under that canopy and what does will be taken up by the tree. Evergreen groundcovers, hostas, spring bulbs, maybe even some dayliles could work.

With the exception of the hydrangeas, all of those are full sun plants and a bit on the droughty side as well. Once the trees grow and fill in more - and that often happens faster than you expect - they will be casting their own shade and those plants will not be very happy. And you do not want to plant something now that will have to be dug up and moved later, disturbing the maple roots when you do. And while it is a totally personal observation, those plants just don't reflect the character of the JM's very well. kaitain4's suggestions are much more in character and kind of the typical JM accompaniments. You could also add hellebores or epimediums to the mix as well.