My first impression is that the dying one is dry. If the root ball dries out before planting, sometimes it is almost impossible to get them to absorb water. One root ball may have dried out and the other didn't. Even though you water a dry root ball it may not be getting any of the water.

Rhododendron and azalea guru Harold Greer noted: "Quite often a plant will get completely dry and then no matter how much water you apply, the rootball will just keep shedding it. The top of the soil may seem wet, and the soil around the plant may even be very wet, but the actual rootball of the plant is bone dry. This is especially true for newly planted rhododendrons, and it is the major reason for failure, or at least less than great success with that new plant. It is hard to believe that a plant can be within mere inches of a sprinkler that has been running for hours and still be dry, yet it can be SO TRUE!"

Unfortunately the other possibility is too much water. It will kill a plant.

probably won't do much good at this point, but would digging it out and letting the rootball soak in water for 24hrs help? I guess anything i do to it can't possibly make it any worse than it already is.

Probably between 15 minutes and 30 minutes should be enough. 24 hours could drown it. You should be able to tell by the increase in weight of the rootball.

Did you loosen the rootball well when you took your azalea out of the container to plant it? That will usually help in encouraging them to establish into the surrounding soil. Peat is an amendment I don't use much myself, preferring compost...peat is the right PH, but close to nutritionally inert and very difficult to moisten when used in large quantities if allowed to dry out.

I'm wondering too if you've always used the crushed stone as a mulch. It's pretty, but your plants might be healthier with something organic in origin (shredded bark, compost i.e. plant remains of some kind) over the root zones. Azaleas do best in a loose, largely organic soil - in the wild they are constantly being 'mulched' by nature with falling leaves, twigs, plant litter that is replenished with new as the lowest layer is breaking down. Perfect for those fine surface roots...

I did loosen the outsides of the root ball all around with a razor blade, one seemed more root bound than the other, but don't know which one. The marble chips were already there when we moved into the house last winter, however there is only a thin layer of it with black landscape fabric underneath. I hate landscape fabric, and the white stones may or may not go as well. But I am going to dig it up, soak it, loosen the roots more, plop it back in the ground and see how she does. I bought them not only cuz they were on sale and were pretty, but because my name is Karen, and I thought, how fitting....lol!

well, dug her up, the ball was slightly moist inside, more dry than moist, so i have her soaking. leaves completely dried up, but the stems still have green, so there may be a slight bit of hope. wish me luck, otherwise, next spring i'll be on the hunt for a replacement. i'll get the ball more loosened up and then plop her back in the ground. Might do that with the rest of them i planted as well, just to be safe.

Karen - hope that works for you.

Having nothing to do with the current condition of your azalea....

You may also want to consider the marble chips, pretty as they are. My own experience with them is nonexistent :) but I do see in a couple of articles where the addition of oyster shell, limestone chips, or marble chips is suggested for raising ph. Is your soil acid enough to stand a potential raise? And I couldn't say if the light layer of chips your photo depicts would even make a difference -

maybe someone else here with experience could address that?

I'm being pretty pessimistic about it surviving, but sometimes plants can surprise you. I've had plants before rise from the dead, so to speak, so hopefully, fingers crossed, my Karen will pull out of this.