Very likely. Normally, they require 1 gallon of water per watering in the Spring and 1.5 gallons in the Summer here in Texas. But in sandy soil, the soil needs to be mixed with organic compost and they must get 50% more water than in regular soils. 3-4" of mulch and a location that is not windy will also prevent the moisture from evaporating quickly. As usual, newly planted shrubs will wilt a lot in the summer but they will recover on their own by night or early morning if the soil is moist. If unsure whether you need to water, insert a finger to a depth of 4" and see if it feel dry or almost dry. If so, give it 1.5 gallons of water or more. If it feels moist or is wet then do not water.

You can start a watering program by testing the soil early in the mornings (at the same thing approx.) for 2-3 weeks every day. When the soil feels dry or almost dry then water it and make a note on a wall calendar to note that you watered on that day and how much (1.5 gallons, etc). After 2-3 weeks, review the information written in the calendar and average the results so you get an idea of how often you had to water (for example, once every two days, once every three days, etc). Then set the drip irrigation or sprinkler to deliver 1.5 gallons on the same frequency (every 2/3/etc days). If your weather changes a lot or say the temps go + or - 10-15 degrees and stay there, do the finger method again for 2-3 weeks to see if you need to tweak things. In the Summer months, increase the amt of water per watering and in the Fall -when temps go down- return back to 1.5 gallons. Since your shrub will not go dormant until Jan-Feb, continue watering during the winter, especially if it is dry but I tend to only water them once a week or once every two weeks. Again, use the finger method to guide you.

Did you feel that you watered it a lot or enough? I say this because you should also be aware, overwatered hydrangeas will often behave the same as underwatered ones. If you see the leaves abruptly go limp over the course of a few days (and you *know* the soil should be moist enough there), there could've been an overwatering issue or the plant is in an improperly drained area or in the vicinity of a natural spring or the water table (the level or depth of ground where there is naturally-occurring standing water). If that's the case, either don't water as much or find a different location for the plant immediately. Continuously wet soils can kill hydrangeas in as little as a week. If there are no longer any leaves, you have a very limited time before the green stems die. Green stems can regenerate leaves,

I should be clear, it was a bare root baby when planted, and very quickly flourished and grew leaves. Being in Central Florida my soil is very sandy so I amended it with both compost and topsoil mixed. I dug the hole approximately 2 foot wide and 2 feet deep to make sure that the soil would be adequate. I did put down about 2 in. of mulch. Because of the surrounding sandy soil, I watered It 2 to 3 times a week with approximately a gallon. It seem to be doing fine, and then all of a sudden it was gone. I do have a dog so I put plant barrier around it to keep him away, but I am wondering if he was "watering" it himself. He does consider every new object in the yard "his". At any rate I have dug it out of the ground and put it in a pot in the house to see if I can revive it. I thank you all for your advice, and I will implement the watering and soil testing ideas. I think I will try again with larger, more eastablished plants in the fall.

Use the finger method to verify the soil moisture level and prevent those surprises. Check it daily for 2-3 weeks at about the same time in the mornings. Note somewhere when you water (1.5 gallons per watering) and then, after 2-3 weeks, review how often you had to water per your notes and give your plants 1.5 gallons of water on the same frequency (every 2/3/4/etc days) using the sprinkler system or drip irrigation.

I know about those doggies.... my three dogs consider the whole yard, the whole house and the whole front of the street theirs! Me (their butler) included. LOL!

Potting was probably a good idea. You might want to try a different kind of plant in that location and see if it behaves any differently.