I have seen deer eat all types of hydrangeas except rough hydrangeas so be proactive and always assume there is risk. A sufficiently hungry deer, rabbit or squirrel can nibble on them. Plantskydd is a spray that you could consider as it does not need to be reapplied after it rains. I have not grown Haas Halo though. If concerned, proactively use stakes, peony hoops and tomato cages in winter when it has dropped all the foliage so you can protect any floppy stems. Frequently pruning too much produces a lot of green stems that are weaker than woody stems so consider not pruning or not pruning more than 1/3 of the stem length. An online ad called the Haas Halo stems as "sturdy" but I would take it with a grain of salt until someone who grows it can comment: https://www.whiteflowerfarm.com/63165-product.html You can do a Hydrangea Forum search for "Haas Halo" and contact via GW mail any owners you find.

Re deer --This product is truly miraculous and absolutely works. For the first time in my gardening life--about 60 years--deer are pretty much no longer a problem. And here at my new house with vulnerable new plantings, they had been the worst I'd ever experienced--until wireless deer fence.

It was rated as a top performer in a study at the Mt. Cuba center.

An online ad called the Haas Halo stems as "sturdy" but I would take it with a grain of salt until someone who grows it can comment

I have seen a mature HH at a friends garden....very large with "sturdy" stems.

you can do a Hydrangea Forum search for "Haas Halo"

from last year:

https://www.houzz.com/discussions/4441166/haas-halo#22403412

It was rated as a top performer in a study at the Mt. Cuba center.

And yet it seems that this variety isn't the easiest to source (that was my experience last year).

Here's a link to the Mt. Cuba Center hydrangea arboresens study: https://mtcubacenter.org/hydrangea. I bought two Haas Halos from Gateway Garden Center in Hockessin, DE. They didn't look so good in the pot, but now 2.5 years later, they are absolute stars in my garden! No flop, beautiful lacecap blooms, lush leaves, and lots of pollinators!

I just bought one at White Flower Farm.

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They are definitely not readily available for sale in my neck of the woods so when I came across several last season I snapped them up. (I havent seen any for sale this year)

US People, Avant Gardens carries them and ships . dont know if they have stock now, but its worth looking ar their website. they carry ”less usuals” and their occasional blogs are interesting.

A superb hydrangea I say.

Been debating getting them too. In south east PA as well. I wanted them based on Mt.cuba. Are the pollinator magnets based on anyone’s first hand experience?

pollinator magnets based on anyone’s first hand experience?

Yes 'James', once the flower is fully developed the bees are clearly apparent.

(Another arborescens I can recommend, if attracting pollinators is important is "Invincibelle Lace" https://www.houzz.com/discussions/6290328/disappointment-with-invincibelle-lace-hydrangea#n=34 )

My Haas Halo blooms are covered in pollinators! They look just like this video from Mt. Cuba... https://www.facebook.com/MtCubaCenter/videos/pollinators-on-hydrangea-arborescens-haas-halo/596984371315360/ 

Thank you so much for sharing helpful comments and photos, everyone! I debated a while and in the end got one from the Green Promise Farms' Amazon store [< linked]... because I happened to have some Amazon gift card balance to use lol. It sure was hard to find in your nearby nursery stores -- the other place online I saw carrying it was White Flower Farm. Anyway, that was in late May. I never had had any experience with the Green Promise Farms, but my Haas Halo arrived healthy, in a very good condition and I was very pleased. I didn't expect blooms this year, but this is what she looked like about a month and a half later.

She is in a full-sun location, but despite the brutal heat we are having right now here in SEPA, she is doing well (we do have drip irrigation, so that may help too). I look forward to seeing her grow and look like the one rouge21_gw shared upthread (those are gorgeous photos!).