You may continue to plant shrubs and trees this month, since their roots are in active growth into November.
September’s cool weather keeps moisture in the soil lots longer than in summertime, and nursery stock planted now is much less prone to transplant shock. Remember to do it in the cool of the day if at all possible, and to water them in thoroughly.
Consider also wrapping the lower trunks of young transplants in protective tree wrap. Otherwise rodents could nibble their bark in the winter, girdling the trunks and killing the trees. For this reason it’s also a good idea to cut back any plants growing up close to your tree-trunks; grasses in particular give rodents winter nesting protection.