Hydrangeas do very well in Atlanta, Georgia (full of red clay) so the question is actually which location they will have the best care. I would select the location where you will be present the most. That way you can take action if there is some issue. The TN Cabin sounds like it may be ok but, since you are not there all/most of the time to correct issues, you may show up and find the shrubs have been eaten by deer, dried out, etc.

It is true that macrophylla hydrangeas don't always bloom well in zone 5. That's because they bloom on last years wood, and a zone 5 winter can damage the flower bud. You might have better success in zone 6, but I would mix in a little bit of soil conditioner when planting.

I live in zone 6..unless I protect macrophyllas over the winter they don't bloom..even when I protect them it's very few blooms..

to get the best info.. you need to ID the exact type you have ... else we might all be guessing ....

where in z5 might also matter.. as it is a large and divergent area ... including some where the ground freezes.. and where it doesnt ....

clay is one of the most nutritious soils.. and is often sought after by professional growers... for a variety of reason ...

for us mere mortals ... it is usually a proper planting and proper watering issue .... you cant dig a hole in bad clay ... which does not drain .. and then fill it with water.. creating a bog .. and wonder why things die .... nor can you let it dry so badly that it cracks inches down into the soil ...

once you learn how to garden in such.. there are very few things.. that will not grow in it ....

ken

Ken, Lori said she bought Macs (H. macrophylla) which will all have the same issues with stems and/or buds not being winter hardy. So she can winter protect or have hit or miss flowers or replace with one of the species that is winter hardy such as paniculata or arborescens.

I bought bloom struck Endless Summer. They would get better care here in IL. The cabin is in north east tn, Rainy and muggy I will try and take one down in the spring and see what happens. The Clay soil will keep it moist. I will add compost for drainage. Should I put in the shade or part shade?

p.s I did buy a few paniculatas as well.

If you put in full shade, make sure it is bright shade. Dappled sun is fine too.

I live in a 6a zone and Macros don't really bloom in my area much unless they are winter protected. Without winter protection, maybe 1 to 3 blooms by the end of the summer.. If I go closer to the ocean where I get into zone 7 and higher, they bloom like crazy.

It's so annoying because I'm right on the cusp of it being warm enough without winter protecting. I'm going to do it anyways since I only have 3 macros and winter protecting 3, isn't a big deal.

“I will add compost for drainage. ”

This typically isn’t a wise idea since the added compost allows extra water into the planting hole, but the clay at the sides and bottom of the hole won’t let the water drain out as rapidly, creating a sort of a bathtub and leading to root rot. I would plant a bit high and add compost and mulch to the surface of the planting area to help hold moisture while still allowing better drainage. Or alternatively, amend an entire planting bed and leave the whole bed slightly mounded.