Be aware that this is Texas (I am in Hurst, Tx, west of you) and our hot, extended summers can hit the 100s for more than two months at a time so they will never look as fine as those in New England pictures and they will require plenty of monitoring in those warm months at first. Shade starting at 10-11am is crucial during the summer months (the leaves will not be harmed if they get full sun in winter or very early Spring).

In my clay soil, raised beds were not used but I amended the soil to acidify the soil and plant them higher than the surrounding soil. I used the instructions in the link below afterwards when planting azaleas (in raised beds) and that may help as both typically have shallow, tiny, fibrous roots in the top 4" or so. The instructions are from Encore Azaleas, specifically for North Central Texas:

https://encoreazalea.com/plant-care/how-to-care-for-encore-azaleas-in-north-central-texas/

Blues are very hard to have here. For years, I have been growing what was a mislabeled Nikko Blue that turned out to be a remontant lacecap. I am using more acidic amendments on it than I use elsewhere with the hydrangeas in the garden... to get blues... but, a funny thing happened on the way there... I ended liking the purple-ish/lavender-ish colors that it got when transitioning from pink so much that I quit trying to get to the blues. I now sprinkle about the same amounts of amendments every year to maintain this shade of color. Oh well. ;o))

As the roots grow outside of your potting soil, your blooms will begin to change to reflect the soil pH in the amended soil. Follow the instructions of the acidifying product that you use to maintain acidity and, if that does not produce enough blues, slowly increase the amount and apply as often as indicated so you do not burn the tiny roots with excessive amounts of sulfur. Once the flower buds open and the blooms age, they do not appear to change that much in response to sprinkling more acidifying amendments. I used to use water from rain barrels until the rain barrels started leaking and were not replaced. But that may help minimize switching from acid to alkaline too. The alkaline water and the soil's natural alkalinity will eventually revert all these amendments back and affect the blues so plan on amending "forever" in order to maintain blues. If you stop, the soil will eventually revert back to its normal pH.

Some plants like Endless Summer Bloomstruck tend to develop multi-color blooms more than other varieties. If that interests you, Bloomstruck (or similar remontant ones) sounds like a good choice.

Remontant, non-white, mopheads would be my choice when trying to get blues in alkaline soil. That is because I get blooms twice a year and I can therefore see how quickly the soil pH is changing the colors and see how it affects the bloom colors faster than hydrangeas that bloom once a year. For example, if the summer blooms did not change color "enough" compared to the previous bloom flush in Spring, that means I need to use more of the acidifying amendments. Over here, adding amendments in early Spring (I just did yesterday) and at the end of the summer is probably the minimum you will need to do; that will help keep the foliage from developing iron chlorosis symptoms but is not enough for blues; you would get pink blooms.

You can reduce watering in the winter but water during dry winters. Begin Spring watering once they begin to leaf out in either February or March but fertilize at starting at the end of March, after the average date of last frost. On very mild years, they have started to leaf out in January so be ready for late frosts. Water deeply and use frost cloth to protect foliage when there are late frosts. A single watering in Spring should provide enoug water to get the soil moist down to a depth of about 8" or less (insert a finger to a depth of 8" into the soil after watering to see). Make sure the drip irrigation will circle the plants and provide all roots with water (as opposed to putting a tube that passes in front of the plant only).

Plan to start using summer-time watering levels once temperatures reach above 85F (around April or May) and maintain 3-4" of any organic mulch (pine needles, hardwood mulch, etc) at all times of the year.

Then add some optional manual waterings when temperatures are above 95F. Then similarly revert as temperatures reduce in September/October. This will minimize -but never completely eliminate- leaf wilting episodes (there is not much one can do to prevent leaf wilting when temps are in the upper 90s or 100s and a quick shower makes water vapor rise from the streets). While you can water daily in a potted environment, watering daily a plant that is planted in the clay soil may cause root rot at some point so, insert a finger into the soil to a depth of 4" and water if it feels dry or almost dry. This will help minimize the chances of getting root rot.

Once established (in 1-3 years), you can reduce or eliminate fertilizers. I like to spread composted manure, use cottonseed meal or use a 10-10-10 general purpose, slow release chemical fertilizer, whichever I happen to have around. But the mulch + acidifying amendments is all they get in some years). Quit fertilizing with all the fertilizers (liquid seaweeds, liquid fish, coffee grounds, regular fertilizers, etc.) about three months before the average date of first frost (last week in November)... so around the last week in August. This way, the plants will harden for winter in time and not be caught in "grow" mode if/when early frosts arrive.

The problem with amending of planting holes is how the hole being given a different texture by the amending affects the movement of water into and out of the amended hole. Whereas if the same dirt is in the hole as around it this doesn't happen.

The next step in the evolution of thinking on this topic was advocation of bare rooting at planting time. Because with intact potting soil root balls there is again the problem of the plant sitting in material of one texture surrounded by material of another texture. Which with potting soils typically being quite coarse means that there is often going to be a persistent problem with the intact potting soil root cylinder losing water to finer textured surrounding soil during dry periods. So that a body may have to be really on top of watering until the specimen roots out adequately.

Just wanted to post an update: all 8 of my hydrangeas are thriving! I know the recent cool and rainy weather has helped, but I am just so thrilled with how they are growing! Fingers crossed they survive the summer.

I ended up using half peat moss and half pine mulch to backfill the holes. 6 of my hydrangeas look like the image I uploaded, and the other 2 are more pink!

Thanks everyone! They bring me a ton of joy.

https://imgur.com/a/4tQf3I2