Backyard Priority Project #1: South Fence Line - Oak Leaf Hydrangeas + Astilbes + Allium

As part of my 2020 planting/buying plan, I've begun to focus on a couple of areas for prioritization.  We have SOOOO much to do in regards to buying new plants per our plan that I thought it would make sense to break things up into chunks. 

The first one up on my priority list is this section of the landscape plan that is visible from our patio.  It calls for seven new Alice Oak Leaf Hydrangea bordered on one side by a series of Summer Beauty Allium and underplanted with Fanal Astilbe out front. 

You'll see in the image above that I've called out 3 'columnar trees' in teal.  That's based on this tree-planning post. 

We have three existing hydrangeas in this area - where the Oak Leaf ones are supposed to go - including this Tuff Stuff and this Everlasting Revolution and this teardown Limelight.  The first two were planted very small and have NOT bloomed, but the Limelight one that I transplanted bloomed last year, so I want to think about what to do with all of these.   

The reason I'm even think about transplanting them is because further to the right, you'll see tha thte plan calls for three Limelight hydrangeas.  Perhaps these three - only one of which is a limelight - could work there? 

Another transplant thing to note here is that I have a couple of Tulip bulbs in this area that I'll have to relocate once they bloom this Spring. 

The other plants to consider transplanting in this section here are the existing lilacs.  I have four in that little space and I'm wondering if I should remove the 'inside' ones and move them further down the fence line?  Also, you'll see a patch of ostrich ferns and a large Canadian Hemlock on the far right. 

That means that when Spring Black Friday comes around - and all season long, I'm NOT going to get distracted with plant lust.  Nope.  I'm not.  I'm going to focus on adding these things to the specific areas.  For this section, that list looks like:

7 Alice Oak Leaf Hydrangeas
12 Summer Beauty Allium
15 Fanal Astilbe
1 Larger Canadian Hemlock Tree
3 columnar trees - based on this post - drawn from the columnar tree dreaming posts I've created over the past month or so.  I'm guessing these won't come early Spring, so I'll have to leave some space for them.  Maybe one of the trees (a deciduous tree) goes *in front* of the hydrangeas? 
Transplanting (because we have some already and I know they spread) a couple of Ostrich Ferns.

For the other backyard priority projects, I'll post separately about them. 

Right now, I'm thinking that I'll focus on the section of the yard that is in between the Hornbeams and the Oak tree that has the tree swing.  Bridging those two areas - which currently has turf - is going to be a nice 'view-changer' from our patio.  And finally, I think considering the far back fence area - behind the newly planted, very young yew hedge in the area that I mentioned recently a potential pussy willow.  Of course, all of this should factor in the 'walking path' idea.  I'm planning on a 30" wide path - which is (according to this piece) enough for one person along the sides with 42" to 48" along the back - and want to contemplate planning for this while not encroaching on the lawn too terribly much.    That idea of planting one of the columnar trees in FRONT of the hydrangeas might help with creating the right space for the path?