Some H. macrophylla varieties may die to the ground but oakleaf hydrangeas are winter hardy in your zone. The exfoliating bark should be able to withstand Zone 6b winters. You do need to provide well drained soil that is not too alkaline (if it is then amend it once or twice a year). Oakleafs tolerate more sun than most other hydrangeas but here in Texas, I provide shade starting around 11am/12pm during the summer months. In sandy soil, plants require 50% more water so keep an eye on soil moisture by mixing the soil with lots of compost/humus/etc and topping it with 3-4" of mulch up to the drip line. In the summer months during year 1, check the soil moisture frequently until you "get the hang of it".

Main thing to remember with oakleafs: Oakleafs are well known for disliking wet feet so make sure your soil drains well (I use expanded shale and compost to absorb water but your sandy soil may have the same effect). I lost one Alice due to extraordinary wet climate one year.

I have 5 munchkin oakleafs planted on my home's very shady north side in a raised bed. No direct sunlight- ever. Zone 9A. Florida. I bought them in October from hydrangea.com. Great experience. They arrived in full green foliage. I limited watering them while I waited for stone masons to finish completing a raised bed against my foundation. I up potted them to 3 gallon containers and significantly limited my watering because everyone had me scared to death about root rot. Their foliage turned red (beautiful) while I waited. Finally planted them in their bed beginning of December. Placed the root ball 3-4" above the soil (because the area doesn't drain well). Turns out the original homeowner 62 years ago burried a sidewalk with 8" of dirt. I didn't know that before I had the raised bed made. Now I have 16" of poorly draining soil... The munchkin are still doing great, though They're still beautiful. Red. Still holding onto their leaves. I have not covered them for two brief frosts. For reference, my Harmony on the southern side is 90% green and 10% red. Hasn't lost any leaves. My southern exposure snowflake has all of its leaves and is a mixture of green, brown and red. So what I'm trying to say is that my munchkins that get no direct sunlight via a northern exposure are doing just as well as the oakleafs getting hours of sun every day (in the same bed as Endless Summers that are still producing flowers!).