Fall is the best time to plant. There are just so many advantages to planting in the Fall. There are fewer pest during this time of the year because of the colder weather. Plants for the most part go dormant during the colder season. Photosynthesis stops. The soil is warmer than the air, so the roots of the plants stick more firmly to the soil and settle. You basically get the plant developement without interuptions!
The ideal time for planting is usually about 6 weeks before the frost (September-mid October.) This period can eaily be extended when the tempature stays up during the Fall. Even if you choose not to plant in the Fall, hardscapes are great to put in during this time! Have everything installed now, and add your plants in the Spring!
Remember... Plant your Spring bulbs now! By planting them now they have a longer period to take root and establish themselves, giving you a higher sucess rate. When planting, make sure the hole you put them in depth wise 3 times their size, and add an insulation layer of mulch on top to protect them from the winter frost.