Perennials: Peonies can be divided and/or transplanted from mid-September to the end of October. First, cut back any remaining foliage close to the ground. Be careful when digging the roots, as they are somewhat brittle. When replanting, look for the small pink “eyes”(the buds) near the top of the roots. This is where the stems will come from next year. If you are dividing peonies, each root should have at least two eyes, preferably three. The roots should be replanted so the eyes are located no deeper than 1½-2 inches below soil grade. One of the primary reasons that peonies don’t bloom is because they are planted too deep, so watch the depth when replanting. Be careful if transplanting/dividing that the peonies are replanted in areas with full sun, as another reason they don’t bloom is insufficient sun. Finally, due to transplant/division stress, the peonies may not bloom the next season.
Trees and shrubs: September is a great time for planting deciduous trees and shrubs. Many deciduous trees and shrubs are safe to plant into the first week of October. Do not plant conifers, birch, redbud, Japanese maples or other marginally hardy species in fall as they may not establish roots before the ground freezes. This year, we have excellent soil moisture, (or maybe too much!), so it is at least not too dry.
Visit http://dnr.wi.gov/files/pdf/pubs/fr/FR0184.pdf for a step by step process in properly planting trees. It is important to locate the root flare (root collar) and have it placed at or slightly above the soil grade and to spread the roots, especially if they are circling or tangled. For information on selecting the best tree for your site visit http://learningstore.uwex.edu/ and type A3864 into the search box for a publication titled “Choosing the Right Landscape Plants: Factors to Consider.” This publication covers topics such as matching trees with soil types and available light as well as selecting trees with good fall color, fruit display or colorful flowers.