Our garden maintenance staff swear by "The Fall Clean-up." The time spent tidying your gardens in the fall saves you twice that amount of time in the spring. There is no actual harm caused to the garden if life conspires against you and "Fall Cleanup" doesn't happen - it just takes more of your time in the spring.
Fall Cleanup should happen after we have had a couple of killing frosts - this ensures all plant material is truly in winter dormancy.
Thing 1 - remove all spent stems & mushy leaves from perennials. The important part of most perennials is below the ground. Generally all perennials will benefit from a layer of compost added to the gardens. This will protect the crown of the plant over the winter and can be tilled in to improve soil quality in spring.(This is a big one for me. Its a win-win) The exception is the beautiful ornamental grasses. We leave those to stand for the winter. They bring life (birds love them) & structure to the winter garden.
Thing 2 - summer & fall flowering shrubs can be pruned now. Once the leaves have fallen, you can clearly see any damaged, diseased or interfering (any branches that are rubbing or crossing) wood. You can take the opportunity of a clear view to prune to control size or shape. This is NOT the time to prune spring flowering shrubs such as Forsythia or Lilac. They have already set their flower buds for spring. Pruning now could result in little or no flowers next spring.
For my garden enjoyment the most important thing to do in the fall is Plant Bulbs! I really feel like we should be sky writing this through the month of October. At the very least it should be in bold caps!!!
Spring bulbs provide the first & the earliest, bright, cheerful colour in our gardens. Yellow, pinks, purples, white & blue in all shapes & sizes. They really lift our spirits & kick start spring. BUT - the bulbs have to be planted NOW. Drifts of Daffodils, pockets of Puschkinia, carpets of Crocus & awesome Alliums all need to go in the ground before it freezes. This is such an easy thing to do. Its a great activity to do with children who will appreciate the magic of emerging bulbs as the snow melts.
Bulb it up! Fall Gardening is as much about investing in the next season as it is about closing down this one.