Ask Mr. Smarty Plants

That sounds like a very serious case of transplant shock. It could have already been damaged when you bought it, if it just basically fell out of the pot. Either your bougainvillea had not grown sufficient roots to support it, or they got broken off at some point. Those little rootlets that are left needed quick water, plus some shade to prevent dehydration. We don't know what condition it's in now, but if you want to try to save it, first, move it into shade. Next, prune off about a third to a half of the upper structure of the plant. Any leaves that are still green, try to leave them on the plant, as it will need nutrition. Water, soak it really good, but make sure the pot is draining well. You don't want them to go from dehydration to drowning. Water again the next day or every other day, and watch for signs of reviving. Do not fertilize. Never fertilize a plant under stress. That can wait until it begins to recover. With less structure to try to keep hydrated, less sun beating down on it, and more moisture available to its roots, it probably has a good chance. If it begins to perk up, perhaps putting on a few new little leaves, you can give it a little more sun every day, but be vigilant about letting the soil dry out too much. You probably won't get any blooms for quite a while.

You probably know that the bougainvillea is not native to North America, but to Brazil. Since the Lady Bird Johnson Wildflower Center is dedicated to plants native to North America, we do not have information on this plant in our Native Plant Database. However, the Texas A&M University AgriLIFE website on Growing Bougainvilleas can give you a lot of information. Since you are in Utah, you might want to give particular attention to the advice on over-wintering this plant.