Dyvonne, you are right, if you were to plant the roses directly into the ground in the boxes, it would certainly slow their growth as the roots would not be able to stretch out until the box deteriorated. Typically what is done is the box is either sliced open in several places, and the bottom cut off before planting, or the rose is taken out of the box all together.
The reason they are all leafing out is because when they arrived, they had been sitting in some cold storage somewhere, waiting to be shipped, and now they have been abruptly left sitting in a nice warm place, and are not climatized to your area at all. If you were to take one of those roses home, and plant it right now, it would be badly shocked.
And yes, you are probably right, those roses have probably not been watered since they arrived in that store. Nursery plants, once delivered to the big box stores, are horribly neglected. The staff at these stores are not trained to care for them properly the way the staff at the garden centres are.
These are the reasons why you will hear several of us bemoan the box stores, and encourage the use of garden centres and nurseries, is because the plants will not have been neglected and abused, and will be taken care of according to their needs. Also, you will find that local garden centres and nurseries will have plants that are hardy for your particular area, as the staff has studied this for you, and only carry what they know will grow. The big box stores however, get mass shippings of all the same plants,all at the same time, from the same place, regardless of climate. That is why people end up buying plants and having them die, not because they are poor gardeners, but because the plant wasn't meant for that area in the first place.
Now that I have had my little rant - poor dyvonne and arkansasrose - you're getting our pet peeves from all sides, first Scott, now me!!!
Sorry about that.
On a lighter note - we are actually having our first beautiful sunshiny day we have had in quite a while so we're enjoying it!