Fall is a great time for planting, though as we get past mid-October, the question is how late in fall can you plant?
Many years ago, I had an entire landscape installed in the first week of November! When I asked the landscaper about whether late fall planting was a good idea, he assured me that as long as I watered consistently until the ground froze and then continued to water again in the spring, everything would be fine. He was right! All the plants -- trees, shrubs and perennials -- took and grew the next year. This was a landscape filled with native and very hardy trees, shrubs and perennials, so it was well suited to fall planting.
Not everything can be planted in late October or November. The University of Minnesota recommends that spring-blooming bulbs, for example, be planted by mid-October. If you are dividing perennials you already have planted, divide spring and early summer perennials in fall and fall-blooming perennials in spring, the U of M recommends. If you are planting something that "pushes the zone," you also may want to do that in spring or early fall in order to give the less-hardy plant a chance to get acclimated before winter sets in.
When doing fall planting, be sure to add a layer of mulch around the plants. The goal of the mulch is not to protect the plant from cold temperatures, but to even out the temperatures in spring so the plant doesn't thaw, then freeze again and experience frost heaving, which can cause serious damage or death to the plant.
One reason to plant in fall is that many nurseries have great deals on trees, shrubs and perennials for fall planting. Check out our Discount Partner list for high-quality nurseries that cater to northern gardeners.
Here's an interesting article on when to plant ornamental and edible plants depending on the type of plant.