Last fall I attended the Colorado Master Gardeners state conference. In one afternoon I attended two classes, both addressed fall garden cleanup, but the classes drew totally opposite conclusions.
The first class was on vegetable gardens. The instructor stressed the importance of meticulous cleanup in autumn. When growing plants for food production, where an abundant harvest is the goal, it is really important to minimize any health risks to the plants. Fall cleanup removes plant parts that may carry disease-causing pathogens, as well as overwintering sites for harmful insects. If you expect to grow vegetables in the same soil next year, you must be really careful to cleanup your garden at the end of the growing season.
The second class was on wild-scaping in an urban garden. Wild-scaping practices are those that make your landscape a good habitat for native plant and animal life. It emphasizes planting native plants and providing water and shelter for critters. Wild-scaping has a naturalized look, and there is little to no emphasis on preventing disease or damage from insects. Food produced in a wild-scape is intended for birds, bees and butterflies, not a human family. This landscaping concept emphasizes leaving debris to shelter bees, butterflies (not all migrate), and nesting spaces and food for birds.
Then there is fire risk. Does leaving debris around increase the risk of providing more fuel for a fire in the urban-wildland interface zone?
What is a gardener to do? I like birds, butterflies and bees; but I am not so wild about voles, rabbits, squirrels and mice. I also do some vegetable gardening. There is a certain amount of cleanup that really should be done – then there are other tasks that can be deferred until spring.
- Remove leaves from the lawn (you can mow and bag). You might be able to avoid this one if the leaves cover no more than 10 to 20 percent of your turf. If that is the case, you can mulch them with a mower and leave them on the lawn.
- Remove annuals once they die back.
- Mulch perennial and shrub beds, if needed.
- Harvest vegetables and thoroughly remove all plant material from the garden.
- Remove seed heads from perennials, you may choose to leave some in place for the birds to snack on and to provide winter interest. Be aware that some plants self-sow and can spread to the point of being weedy. Native birds will eat seed from purple coneflowers, aster, goldenrod, little bluestem, big bluestem, black-eyed Susan and many other native flowers. If you do cut back seed heads do not remove green foliage, wait for it to die back. Foliage left on perennials will help shade the crown of the plant, as well as the soil in the immediate root zone. This shading can moderate drying and heaving caused by freezing and thawing. Foliage also acts as a snow catcher, providing a bit more insulation and capturing a bit more moisture. You may also want to leave some foliage in place as habitat for bees and other beneficial insects. However, if you are plagued by voles and rabbits, those areas will also provide shelter for them.
- Cut ornamental grasses back and clean up under shrubs. This can be done in autumn or late winter. If vole or rabbit damage is an issue in your garden a fall cleaning may eliminate some cozy nesting spots for voles and rabbits.
- Remove fallen leaves from perennial beds. You can use them as mulch in other parts of the garden.
- Remove any dead trees from your garden, this will reduce fire risk. Dead trees can provide shelter for birds, many species of birds rely on dead trees for nesting, food storing, and hunting, roosting and resting. If the tree doesn’t pose a fire risk then leaving it in place may be beneficial.
Consider the purpose and intent of your landscape, then weigh the pros and cons and decide what is important to your gardening goals. Then clean up as much or little as those goals dictate.
When you have questions, Colorado State University Extension has research-based answers. Get answers to your horticulture questions by visiting ask.extension.org any time day or night. You can also visit or call the help desk 719-520-7684 Monday to Thursday from 9 a.m. – 12 p.m., or email CSUmg2@elpasoco.com. The help desk will be staffed with volunteers during those hours through the end of September