Rhododendrons Blooming - May 2020

After taking a full year off, our back stoop rhododendrons are blooming again this year with beautiful purple flowers. Both shrubs (these are evergreen...which always amazes me) are pictured side-by-side above, and there are individual (slightly larger) individual photos below in this post.

The last time these flowered was when they were planted in May of 2018.  In 2019, like all of our flowering trees/shrubs, the buds appear to have been killed by a cold Winter.

On the left (above), is the Southern one.  On the right (above), is the one to the North of the stoop.  The southern one is larger in both dimensions - taller and seemingly wider as it has some branches that are spreading out a bit more.  It has taller blooms and - at this point - more of them.  The northern one is more compact, but has what seems like deeper green foliage.   

I applied Wilt-Pruf to both of these last Winter and...frankly....I'm not sure if it helps.  Seems like it is one of those things:  you only know when either it didn't work...or when you didn't apply, but should have.  I also showed a photo of these in April - when the weather was still cold.  

As for the size discrepancy, this appears to be a pattern with the Southern one - which did without Wilt-Pruf in one year - has emerged as the slightly stronger plant.  

These shrubs were added in Spring of 2018 (per our plan) and have grown without any pruning from me.  

Here - below - is the Southern one: 

And...here - below - is the Northern one: