By November Seattle has usually had a good hard frost and most of our herbaceous (non-woody) perennials have either turned to mush or look a bit tattered. Before you give in to the temptation to cut back everything in sight, consider the advice of natural gardening advocates James Van Sweden, author of Gardening with Nature (Random House, 1997) and Jackie Bennett, author of The Wildlife Garden (David & Charles, 1993):
- Leaving seed heads and dead stems over the winter gives the garden winter interest, especially if we get some snow
- Seed heads from Black Eyed Susans, Echinacea, Larkspur and Evening primrose provide bird food
- Beneficial insects hibernate or over-winter as eggs on plant waste
- Marginally hardy plants like some salvias and lavenders benefit from the little bit of frost protection from the desiccated stems
On the other hand, sanitation is critical if your apples suffered from codling moth or scab or your roses suffered from black spot. Rake up and dispose of every single diseased leaf or infected fruit. Insect and disease organisms also over-winter on plant debris, so if you had a problem this year, start the treatment now with a thorough clean-up.