Containerizing Non-Blooming Hydrangea Macropylla!

In 2014-15 I decided to begin to dig up some of the hydrangea macrophyllas that have been having trouble blooming after winters and have been placing them in large containers (~20-24" diameter, ~10-15 gallon). This is because I am transitioning to overwintering only the top performers outdoors (the ones that are about guaranteed to bloom on current year's growth). The containers reside in my (attached and indirectly heated) garage for the winter and are watered about once monthly from December-March.

Shown: Pink n' Pretty (Monrovia) and Abracadabra Orb (Proven Winners).

The advantages of containerizing are as follows:
- freedom of placement around the property (masks, covers, fillers)
- guaranteed bloom
- larger size than if overwintered in-ground and suffering dieback

The following cultivars are the ones I am currently growing in containers:

All Summer Beauty (pale pastel variant of Nikko Blue)
Preziosa (fairly hardy outside, but need to guarantee a larger plant with the unique mophead blooms!)
Firelight / Leuchtfeuer (2) - for bookend use on my deck
Mathilda Gutges / LA Dreamin'
Pink n' Pretty
Abracadabra Orb
Forever & Ever Blue Heaven
Forever & Ever White Out (3)
Forever & Ever Fantasia
Forever & Ever Red / Maltisse
Forever & Ever Red / Red Sensation
Early Blue
Pia
Doublicious
Trophee
Pink Sensation
Hot Red
Red Beauty
Unnamed blue/pink mophead
Midnight Duchess (lacecap)
Mme Emile Mouillere
Queen of Pearls
Double Delights Perfection
Claudie (lacecap)
Blue Wave (lacecap)
Zorro (lacecap)
Free Bird (new!)

Here are some additional pictures:

West side of house (mostly shaded)

Under deck, front: Trophee, Doublicious, Blue Wave, Blue Heaven. Rear: Preziosa

Smaller containers on front porch: Early Blue, Pia, F&E White Out (2), Pink Sensation, Red Beauty, Hot Red.

Swing Bookends! Free Bird, All Summer Beauty