When planting in the early to mid fall, the plant’s root system has time to establish during a cooler time when drought is normally less of a problem. Then the plant can go into winter slumber after having gotten comfortable with its situation. That being said, it is by far best to get planting done by mid fall. Although, I have planted as late as the end of November and maybe even into December and been successful despite myself. Planting that late is not ideal. But what if, for instance, you happen across a plant sale where they were practically giving away named hybrids of plants you want? Or what if your neighbor, who does nothing but garden, decides to divide his/her prize perennials at the last minute and give some to you? And, while this probably does not apply to you, what if you didn’t get around to planting the plants you purchased at full price way back in the spring? Let us assume that you’ve waited, for good reason, until late fall or early winter to plant a couple things. There are some steps you can take to increase your chances of success. Make sure to water the plants well once they are planted and mulch with straw or small pine boughs or branches with leaves still attached. This will cut down on frost heaving and wind damage. Take the time to look at the plants in the weeks after you plant them to check for frost heaving and push them back in a bit if you notice this is happening and water them regularly if the winter has been dry. Your efforts should be rewarded with live and particularly hardy plants in the spring!