Shrubs At Feet of Linden Espalier Trees - An Exploration - April 2022

This is the third in a series of shrub exploration posts that are helping me think and plan how I execute on my #1 priority for 2022:  plant shrubs in a deliberate way.  I started with this 20' area where I need to replace some lilacs with an evergreen layer and three Tardiva Hydrangeas. Yesterday, I looked at an adjacent spot that calls for a similar (but different) evergreen layer fronted by three dwarf Little Lime Hydrangeas that are planted in a way to NOT foreclose a potential path.  Today, I'm looking at the area that lays at the feet of the pair of Greenspire Linden trees along our fenceline.  Here's what it looks like today:

Orange ovals = Greenspire Lindens in a horizontal cordon espalier.  Green ovals = Summer Beauty Alliums.

I've always wanted a little bit more structure in this area - but haven't done anything meaningful. There are two problems:  First...the plan is SILENT here.  No plantings.  Second, there's a bit of an elevation/slope that is going on here that I think should be dealt with as part of plantings.  

Let's first address the idea of the slope.  Could I take the learnings from my screened porch retaining wall and apply it here?  I could see something close to an outcropping that is set about a foot tall from the lawn grade to provide this bed with a flat surface.   I've put that concept in the annotated photo below - the blue lines represent a potential retaining wall.  What else is there?  A combination set of evergreen shrubs.  The yellow ones are (for now) something more pyramidal.  With the red circles being more circular/balls.  I'm not totally sure yet - but could this be a place to do something like Linda Vater's boxwoods style that includes rows AND balls?  Or, just a row of them like this example.

These could be yews or they could be boxwoods.  Below is a photo from Hinsdale Nursery showing their Buxus 'Green Velvet' that would certainly do the trick here. 

Just like the other posts, this exploration is helping me deal with a shopping list.  

So far, here's what I've come to understand for these three areas now.  First the hydrangeas + evergreens:

• Three upright evergreens (Yews, Thujas, Hemlocks)
• Three other upright evergreens (different ones from above)
• Three Tardiva Hydrangeas
• Three Little Lime Hydrangeas
• And now...eight to twelve boxwoods.  

Last year, I picked up some TINY $5 boxwoods late in the season and planted them knowing it would be many seasons before they were meaningful.  I also bought one (I know, I know) Green Mountain boxwood that is upright.  Maybe that's the plan for this area, too.  Due to the volume (8-12), maybe smaller is the right move budget-wise. What is to be determined is if I could plant this season WITHOUT taking on the retaining wall project in a way that would NOT require replanting.  The biggest variable is how 'high' I plant these, I suppose.  By adding material to the front of the bed - that for now - may 'run' down to the lawn, it might allow me to plant now and do the wall later.