Zone 7B here. Can hydra overwinter in a pot outdoors as long as I give it a blanket of leaves ?

I still have some leftover Boxwoods I've overwintered for 4 winters seasons already in 10 gal root pouches with no issues - leaving them outside to the elements. I currently have a 10G Hydra I repotted into a fairly light mix of bark/super coarse perlite into a 30G root pouch as well. I was just planning to give it a leaf blanket.

I would keep the pot in my garage or shed. Just don't forget to water it.

Luis. Would it not be a good idea to let the Hydra get used to the ~4 seasons~. The garage never dips below 65F as I keep it heated in there, tinkering away on the weekend toys,

In zone 7, you should be able to winter a containerized hydrangea over outdoors without issue. It won't freeze, especially in that size of a pot, but you might need to protect stems against cold damage to the flower buds.

a1an, the only problem I can think of (regarding "tinkering to let the Hydra get used to the ~4 seasons~ ") is that exposure to the cold when left outside may kill a potted plant's flower buds (located at the ends of the stems). On my zone 8a, you can still loose the flower buds when the shrubs are outside and the weather suddenly changes... like what happened this year in early January... temps crashed to the high teens and many mopheads had no blooms.

But! I suppose you could do it as long as you can monitor the weather and then bring them into the garage if you hear that temps will soon be coming down a lot. I completely missed the news this year though. I should have tried to winter protect them ahead; and I even had the wire cages nearby for such an occasion and still... I had an Alzheimer moment. :0) I did not think about protecting until a couple of days after the lows. Thaaaat is when my brain went ding!, followed by 'oh, darn', followed by 'did I forget to overwinter?'. Not exactly those words. Hee hee hee. It went downhill from there. :o) Ha.