September is a great time to plant and there are a number of reasons this is so. The daytime temperatures are cooler and the soil temperature is still warm, a perfect combination for planting perennials. Typically, there are fewer insects and diseases to contend with, which helps reduce the stress on newly planted perennials and you generally have more time for gardening in the fall. The weather isn't quite as tricky as it is in the spring and you don't have that "spring rush" feeling to get everything done after winter. The advantage this time of year is the soil is warm and dryer making it easier to add amendments. In our typical clay soils, that means adding organic material to the planting site is key. easy to take home and place in the garden. Amendments should be incorporated into the planting site at a 50:50 ratio with the existing soil. Prepare a spot twice as large as the container your plant came in and half again as deep. Remove the plant from its container and break up the root ball. Place the plant in the planting hole just below grade, enough to form a slight depression in the soil. This will help keep water from running off too quickly. Even though the temperatures during the day are cooler so there's less moisture loss, it's important to keep your plants watered as fall deepens into winter. All plants will handle winter weather better, if they are well hydrated. In short, planting perennials in the fall gives your plants time to establish and develop strong root systems, which will give them a vigorous head start next spring.