Fall usually is a great time for planting or transplanting : Temperatures have moderated, and rainfall typically is more plentiful. It’s simply not as hard on the plant. And it's much more pleasant for you, too, to work in the garden this time of year!
However, there are some plants that don't always do well when planted in the fall. In most cases, this is because they need ample time to establish a strong root system to help them survive winter. Some plants also are more sensitive to cold so they tend to do better when given a longer period of time to get acclimated to their new home. Because you have no way of knowing how rough the coming winter will be or when the first frost will arrive, it’s best to hold off on planting these particular plants until spring.
If you absolutely must