As autumn arrives, gardeners face the seasonal challenge of garden cleanup and managing the fallen leaves. As the growing season comes to an end, fall is the ideal time to prepare the garden for the colder months ahead. Managing fallen leaves and tackling fall garden cleanup isn’t just about aesthetics; it’s a vital step in maintaining soil health, preventing disease, supporting wildlife and pollinators, and setting the stage for a thriving spring.
Leave the Leaves (When You Can)
Overall, the goal for fall cleanup is to leave behind as much as we can to overwinter. There are, however, a few situations where the cleanup and removal of leaves and debris are beneficial, particularly in the vegetable garden and lawns.
Fallen leaves and dead plant debris provide several benefits for many garden areas. Leaving the leaves, stems, dried flowers, and seed heads of many plants provides more interest through the winter months by providing something interesting to look at, rather than a flat bed of mulch. Leaving the plant materials also provides an extra layer of protection for the crown and root system of perennials, bulbs, or tender shrubs. Plus, the dead stems and leaves collect fallen leaves, adding even more protection. Leaving the plant material in place and removing it in early spring, rather than in fall, also helps provide food and protection to native pollinators, beneficial insects, and wildlife, such as birds.
Garden Cleanup by Area
When the leaves start to fall and frost kills back garden plants, cleanup (or lack thereof) can begin. Each area in the landscape has some unique considerations.
Perennials | Shrubs | Lawns | Vegetables | Fruit Trees | Perennial Fruit & Vegetables | Annuals | Tender Perennials | Containers
Perennial Garden and Shrub Borders
It is not necessary to clear-cut the perennial garden after the first freeze of the season. Leaving the leaves, stems, dried flowers, and seed heads of many perennials, such as coneflowers and ornamental grasses, provides more interest through the winter months, as well as protection from extreme winter temperatures. Additionally, it provides food and shelter for insects and other animals.
Remove Diseased, Pest-infested, and Seedy Plant Debris
While it is largely beneficial to leave the foliage in place through winter, removing plant material in the fall after it has naturally died back should be done for perennials with disease or insect pest issues during the summer. The plant debris of bee balm and phlox with heavy powdery mildew infestations, or iris with borer problems, is best removed from the garden and destroyed. Additionally, those perennials that tend to be weedy or spread aggressively by seed, such as blackberry lily, garlic chives, or golden Alexander, benefit from late-season deadheading and clean-up to prevent them from being too weedy. Diseased and infected plant material and seed heads should not be composted. Most home compost piles do not get hot enough to kill pathogens, insect larvae, or weed seeds.
Treat Shrubs and Mixed Plantings Similarly
Shrub borders and other landscape beds with mixes of perennial and woody plant material can be treated much the same. Leave behind as much as you can, but clean up leaves from diseased shrubs, such as lilac with leaf spot. The stems of cut-back shrubs, such as butterfly bush and bigleaf hydrangea, can also be left in place until spring. This has the added benefit of allowing more material to regrow if not completely killed back due to a mild winter.
Lawns
Turfgrass plants utilize light, water, and nutrients to manufacture food. In the fall, lawn areas beneath large trees are often completely covered with leaves. The leaf debris prevents the turfgrass plants from manufacturing and storing food prior to winter, and can block light, causing areas of the lawn to die back and leaving behind patchy, unsightly areas of dead grass that are more prone to weeds.
Collect and Redistribute or Compost
A layer of leaves where little or no grass is visible will need to be managed. Leaves can be collected by raking, blowing, or using the collection bag on a mower, and then removed from the lawn and added to a compost pile or sent to a composting facility. Leaves can also be relocated to other garden areas and serve as a mulch over the winter. Be sure not to layer leaves too thick as they can smother the crowns of perennials if too deep.
Mow Them
Gardeners can also manage leaves on the lawn by mowing. Chopping the leaves up with a mulching mower can help return organic matter to the soil, benefiting the lawn, and for most people, it is easier than raking and removing them. The leaves must be chopped into pieces small enough to fall down between the blades of grass. When finished, very little leaf debris should be visible. Mowing is best done when the layer of leaves is thin and dry, so it's recommended to mow often throughout the fall. If the leaf layer is thick, mow over an area more than once.
Vegetable Garden
Good fall clean-up is necessary in the vegetable garden, removing all leaves, stems, fruit, and other plant parts after the first frost. Most edible plants grown in home vegetable gardens have significant disease and/or pest issues that can overwinter on plant debris, increasing their impact on crops in subsequent years. Removal and destruction of the diseased plant debris reduces the severity of many diseases in the next growing season.
Composting the plant debris is a good option, assuming you have a compost pile that heats up to at least 140°F, which will kill most pathogens. Most home compost piles do not reach this temperature, but most municipal composting facilities do.
Learn more about vegetable garden management in this article: Growing and Caring for Your Vegetable Garden.
Fruit Trees and Perennial Edible Plants
Fruit trees and perennial edible plants, such as strawberries, raspberries, rhubarb, asparagus, and grapes, benefit from good sanitation in the fall as these plants have some significant and common disease and insect pest problems.
Remove and dispose of dropped fruit from apples, pears, cherries, and other fruit trees to reduce overwintering insects, such as codling moth and apple maggot. Rake and discard fallen leaves that may harbor pathogens, like apple scab spores.
Remove any plant debris of edible plants showing signs of disease, such as anthracnose-infected raspberry canes. If insect pests, such as the asparagus beetle, were particularly bad this past growing season, remove and destroy any plant debris to reduce overwintering sites for the pest.
Whenever possible, leave behind healthy foliage and stems to aid in overwintering. The blanket of foliage, and the leaves it collects over winter on plants like asparagus or rhubarb, can provide protection from harsh winter conditions. Just be sure the foliage does not smother plants, as can happen with crops like strawberries.
Annual Beds, Tender Perennials, and Containers
Beds and containers with annuals can be cleaned up in the fall. These plants will not overwinter, and while some wildlife may benefit from the cover that the dead leaves and stems could provide, the impact is significantly less than that of perennials and woody plants. This is due to the fact that annuals are largely non-native plants. These areas are often smaller in size and isolated from other areas of the landscape. Additionally, the soil in containers freezes and thaws more readily throughout the winter, leading to inhospitable conditions for insect overwintering. Containers often benefit from being cleaned and stored indoors to prevent cracking, further necessitating cleanup.
Any plants with disease or pest issues should be removed from the garden area in the fall to reduce the likelihood of infestation next year. Additionally, seedy annuals, such as cleome and cosmos, benefit from fall cleanup to reduce unwanted reseeding. This plant debris should be destroyed and not placed in the compost bin since most home compost piles do not reach temperatures hot enough to kill pathogens, insect larvae, or weed seeds.
Tender Perennials must be dug and brought indoors to overwinter, so their removal from the garden in fall is a necessity. Learn more about this process in this article: How to Overwinter Tender Perennials.
More Information
- Fall Garden Tasks
- How to Clean and Disinfect Plant Containers
- Frost and Freeze Dates in Iowa
- How to Protect Trees and Shrubs from Animal Damage Over Winter
Photo credits: 1: Svetlana/AdobeStock; 2: Alexandr Blinov/AdobeStock; 3: PaulMassiePhoto/AdobeStock; 4: barmalini/AdobeStock