I would expect lots of wilting and quickly browning/fading blooms on many first year hydrangeas due to transplant shock and perhaps moisture issues. How do you define "a good bit of sun"? Can you give us the times of day when they got sun during the summer time? Are they getting a lot of afternoon sun?

I assume you mean your new hydrangeas are "Endless Summer". It sounds like they need to move to a new spot, although I have some that get a surprising amount of hot afternoon sun and they do well. The key is their root conditions. If the roots stay cool from mulch and have adequate moisture all the time, the plant may wilt in the heat of the afternoon, but bounces back by morning. This is not ideal, though, and I have trees growing to eventually give them afternoon shade. If you have a site with morning sun and shade from noon or so on, they'll be happier from the start.

When you move your plants, if they are not going into a prepared garden bed, dig the hole for them three to four FEET wide. That hole will accomodate their roots comfortably even when they are full grown. Dig the hole BEFORE you lift the plant from its present home. I would advise that you add a very generous amount of either homemade compost or manure (Black Kow is one brand) to the soil in the hole. Do NOT add commercial fertilizer. I usually lay the compost over the entire hole area before I start digging. I want it to be three or four inches deep.

Dig the hole one spade's depth, and dig and break, dig and break, until the soil in the hole is soft and crumbly looking.

Then remove soil from the middle of your big hole and plant your hydrangea with the surface of the soil around the roots at or slightly higher than the surrounding ground level. (This is important.)

Refill the hole with the soil you worked soft, MULCH the entire hole with 2 to 4 inches of either pine straw, chopped leaves, or shredded bark.

Then water it in well. You want the soil in the entire hole to be nice and moist. After this, the plant needs about an inch of water per week. (At least in my area, there is usually sufficient fall and winter rains to supply this.) Don't overwater! If you haven't had rain, stick your finger about an inch into the soil near the roots. When you take your finger out, rub it against your thumb. If you can feel moisture, the plant is okay. If not, give it a good drink.

This is a pretty good aerobic workout! I find it helps to cut the circle for the hole with the spade first, and then cut it in a grid pattern, in both directions. That way, when I start lifting and breaking, I get smaller chunks of (clay) soil and they're not so heavy for my back. If necessary, dig one hole a day until you're done. It's best to take your time and do a good job. If you get it right, you should never have to do it again and your plants will thank you with boatloads of blooms all summer long. My Endless Summers give me as much pleasure as any plant I have ever had, and that's saying something. :)