"Garden clean-up" means different things to different people, but for perennial gardeners it does not mean uniformly cutting back everything. Before you whack back all the plants, ask why you are doing it. Is that one a plant to leave standing? Also ask, if you cut it back, how far is best -- but that's the topic for next week.
Plants to leave standing
For a winter buffer: Some plants are best left with the whole tops intact just because it gives them better odds of returning next season, the ample crown giving some extra buffer against dying back. We do this with mums (especially those put in a bit too late) and Buddleia (butterfly bush), because they often don't die back to the ground if you leave the tops on. Then you can decide in late spring exactly where there is life and where to prune for shape and size.
For the birds: Seeds are very important for some migrating or resident birds (finches, woodpeckers, cardinals, chickadees), and both the seed-heads and the birds are beautiful, so why not leave any seedy tops standing? Many of us don't look closely at our plants, and here is a time to do so. Go pick apart a couple of dead flower-tops to find which ones have lots of seeds. (Caution: seed collectors are born this way!)
Examples of bird favorites: Rudbeckia (black-eyed Susans), Echinacea (coneflower) and many Coreopsis.
For the butterflies and beneficials: Remember the effort you made to plant flowers to attract butterflies or beneficial insects to help hunt the garden pests? Well, don't undermine your intentions now by cutting away all their hiding or pupating places. Next summer's butterflies and moths are pupating under those tipped-over perennials, and the helpful crop of lady beetles, ground beetles and spiders have laid eggs or remain as adults just under the leaf-litter or mulch. In this world, neatness is not a good thing.
For the beauty of it: The term "winter interest" is used for anything that pokes above the snow to give structure and break up the monotony of a garden. Some of the stars are evergreen trees and shrubs and ornamental grasses.
However, lots of perennials remain green or maroon and look interesting when the snow is not too high; others provide dramatic silhouettes. Consider Hellebores, Bergenia, or many maroon-leaved Heucheras (coral bells) for interesting looks during the January thaw. For shape, do leave standing the dramatic spikes of Ligularia 'The Rocket', Liatris, Astilbe, or plume-like Aruncus (goatsbeard). Winter is too long and the garden too starkly white without them!
If you are a neat-nik, you may not have it in you to leave perennials standing. If so, let's discuss how much to cut back next week. For the rest of us, we'll see which ones should be cut back to prevent disease, thwart slugs or problem insects, or prevent a really messy spring.
Sally Cunningham is an educator in Consumer/Community Horticulture with Cornell Cooperative Extension of Erie County, and gardening book author.