Doing a google search on remontant hydrangeas, brought me to this thread. I own 'Wedding Gown' & 'Pistachio' or 'Glam Rock' as its known across the pond. Both hydrangeas do not get huge figure about 3' X 3'. 'Wedding Gown' I have noticed, in our zone 7 winters w/o protection dies almost to the ground and emerges with new growth in spring. The plant blooms on new wood. I have not encountered 'die to the ground' with 'Pistachio'. Both are well behaved in a Northern exposure and a Western exposure in the shadow of a magnolia.

H. quercifolia is somewhat challenging plant for z5. The most of the problems will occur in a first few years. Once established it will be relatively trouble free plant, though not a reliable bloomer. After all it's a z7-8 (NC, GA) native plant. First, it need 2-3 years in ground to become fully established. Being technically root hardy to z5 it still need very thick layer of mulch and burlap wraping in a first couple of winters. Spring/early summer planting is highly recommended for z5-6. Second, of all hydrangeas, young oakleaves are the most succeptible to root rot while still can't stand drought. Therefore, one have to find PROPER watering regimen to satisfy this requirement. Again, thick layer of mulch could be handy. Third, it blooms on old wood and you are back to square one for winter protection as you would be with the most of macrophyllas. Winter protection ala 'hayseedman' for quercifolias will be not only questionable due to the rangy pattern of growth, but most likely will be impossible for the most of them due to their sizes, assuming they'll not die back every other year. 'Alice' in particular, is one of the largest h.q. and could easily reach 8x8' in just 3 years and 12x12' in 5 years if no dieback. IMO, dwarf cultivars, such as Pee Wee or Sike's Dwarf (both look identical to me anyway) are the only quercifolias that could be/should be attempted to grow in solid z5 on condition that grower is determined and will put reasonable effort to protect them. Fourth, indeed, fall foliage of oakleaves is a site to behold. However, in order to develop fall color it should be grown in a considerable sun, say 3-4 hours, and here you'll have another contradiction. Location with 3-4 hours of tentatively morning sun in a summer most likely will become a 6-8-10 hours of sun in a winter and such exposure most definitely will dry flower buds or even the whole branches by the spring, thus you'll have a huge non-blooming plant in a best case scenario. Sorry for the doom and gloom, but that is how I see it. Re: 'Blue Billow'. It wasn't me who touted it, but Hayseedman reported that it blooms RELIABLY for him in z6 WITHOUT any protection. In my z6b garden I don't protect any hydrangeas except trying to chose location wisely, and indeed B.Billow bloomed for me the last three years on a row, including very cold winter of 2003/04.

There are so many varieties of panicle hydrangea now, in addition to limelight and little lime. These are an unnamed variety from a grower here in east Texas - they only get about 6 hours of full sun, but they really responded to this cold winter. The flowers age kind of pinkish then dry nicely for arrangments. We've also had good luck with the smooth hydrangeas (h. arborescens) such as Annabelle in similar condition, actually in the same bed - these might be 'Incrediball' - I have to wait till fall to climb in to see the tags. We did plant them on the east side of some taller shrubs (viburnum 'Opening Day' and 'Rosalinda' Indian hawthorn, which is recovering from last winter's freeze) to provide some afternoon relief from the hot sun.

I do not remember seeing paniculatas but, when one of my aunts used to live in Ocala, I used to fly into Gainesville (GNV) and drive to Ocala to visit her. Throughout the years of visits, I saw hydrangea mopheads (she also had them planted in the ground) in her house in Ocala and I also saw hydrangea arborescens and oakleaf hydrangeas (not many; just a few) elsewhere in town. Due to the sandy soil, sunlight and winds, the mopheads that she had in the ground required morning sun, year around organic mulch, lots of water, mixing organic compost with the local soil 50/50 when planting; putting a 1" layer or so of organic compost every Spring as well as fertilizing regularly almost all year (to deal with nutrient deficiencies). She did not do a soil test when moving there although I suggested it. My aunt's mopheads were in morning sun only. For paniculatas, the University of Florida recommends a non-windy location with morning sun only. https://gardeningsolutions.ifas.ufl.edu/plants/ornamentals/hydrangea.html You could try growing them in pots/half wine barrels at first or always. I would not put them in full sun there though; morning sun only. Be ready to water them a lot if planted in the ground. Watering and the 'too well' draining sandy soil was the problem over there when planted in the ground. Hydrangeas went dormant quite late over there (January-ish) but I did not visit when they were leafing out so I am not sure when that happens (probably earlier than other places). To see if they need water, insert a finger into the soil to a depth of 4" or so and water if the soil feels dry or almost dry. Hydrangea roots are shallow, tiny, fibrous and they typically grow down to 4" or so. To see if they have enough water, water as usual, wait for the water to dry and then insert a finger into the soil to a depth of 8" or so in several spots to see if the soil feels dry somewhere. If it does feel dry somewhere, consider using more water. PS - If you decide to take them (and either grow in pots or in the ground), post an update in the future.