Fall clean up is a very important part of the yearly gardening cycle. By cleaning up the garden you are doing more than just making it look tidier, you are helping to reduce disease and pest problems for next year’s garden.
As you go through your garden remove any diseased leaves, twigs and branches. It is best not to compost them, as our household compost does not usually get hot enough to kill off diseases like black spot or bacterial canker. Dispose of them in your household garbage or take them to Salish Soil. Also prune out any broken twigs and branches, as these can be entry points for several kinds of fungal and bacterial diseases. When pruning out diseased branches and twigs it is a good idea to dip your secateurs in a mild bleach solution or other household disinfectant frequently to prevent the spread of the disease.
Any plant material that is not diseased should definitely be composted. All those leaves from your perennials make an excellent addition to your compost bin, as do fallen leaves. A tip for the tree leaves in your yard: if you want them to break down faster in the compost bin just pile them up, run them over with the lawn mower and voila, you have excellent mulch for your compost bin and your garden.
When cutting back plants like peonies, lilies and hostas, mark them with a stake so you know where they are in early spring.
Not all plants should be cut back in the fall. Leave the stalks of rudbeckia, echinacea, gaillardia and grasses like the pennisetums and miscanthus. They look absolutely beautiful in the fall and winter with frost outlining the stems. In addition, the stems help to protect the crown of the plants from frost and wet.
Your rose bush is another plant that should not be pruned now. Wait until late February before you prune it back. If you prune it now it will send out new growth that will be damaged or killed in the first frost.
Decide which dahlia tubers to dig up and which to leave in the ground. If you have well-drained soil or your dahlias are planted under an overhang, leave them in the ground and cover them with a layer of mulch. Those in heavy clay soils are prone to rotting so dig them up. After the first hard frost when dahlias go black, cut down the stalks and lift the tubers. Leave the soil around the dahlia tubers and dry off the clumps. Store them with the dried earth around them as an insulating layer in a burlap bag or lined box. Leave them in a cool dry garage for the winter.
From Bob Tuckey (The Natural Gardener) and Carolyn Herriot (A Year on the Garden Path)