For most parts of North America spring is the best time to plant new apple trees. The exact month for planting depends on where you live and our spring shipping dates give a good indication of the best time in your state.
In warmer zones (7 and above) such as southern California, areas of the Pacific North West, and some of the southern states, it is also possible, and often preferable, to plant in the Fall - usually November. However Fall planting is only advisable if minimum winter temperatures are not likely to be much below freezing. If in doubt, spring planting is safer.