It is finally time to finish cleaning up the lawn, flower and shrub beds and other planting areas to get them ready for winter.
The first frost in Columbus arrived last week, albeit a few weeks later than the average date of first fall frost, and leaves have started to accelerate their descent to the ground. These two events are phenological signals to gardeners that it’s time to complete the annual fall cleanup of leaves and spent annual and perennial plants.
Fall is an important time in lawn and landscape maintenance, as many insect and disease problems encountered during the current growing season may survive until next season on or in plant debris. Cultural practices completed before winter arrives can ensure a healthier landscape next spring, but these same practices can also have a detrimental effect on beneficial insects, birds and the environment.
Ecologically competent gardeners understand the need to strike a balance between a fall cleanup, which results in a landscape resembling the tidiness of the barren surface of the moon, and one that resembles the wildness of a jungle singed by a hard freeze.
Leave the leaves on the ground?
There is an ecological benefit to leaving some leaves on the ground in shrub, annual and perennial plant beds, as the leaves will add some nutrients and organic matter to the soil as they decompose this winter. A layer of leaves will also help moderate soil temperatures encouraging root growth of newly planted perennials and shrubs, and preventing soil heaving caused by cycles of freezing and thawing.
Shallow layers of fallen leaves can also provide winter habitat for insects. Unlike the monarch butterfly, which migrates to overwinter in Mexico and California, many butterflies and insects — including some species of bees — overwinter as eggs, caterpillars, pupae or adults in and around the garden among plant debris and fallen leaves.
By leaving a layer of leaves in planting beds, you will be providing winter cover for spiders, slugs, worms, beetles, millipedes, mites and other organisms that provide food for chipmunks, turtles, birds and amphibians.
I would be wary of leaving a significant layer of fallen leaves on the lawn, as they can easily smother cool-season grasses that may not go dormant until January, depending upon the weather this winter.
The best method for leaving fallen leaves on a lawn is to chop the leaves with a mulching lawn mower so that the small leaf particles settle into the thatch layer between individual blades of grass.
The birds and the bees and why seed heads should be left intact
Seed heads of yarrow, coneflower, rudbeckia, and other perennials provide an important source of food for overwintering birds, so consider leaving the seed heads of these plants intact for the winter. These plants can be trimmed close to the ground early next spring.
The stems of hollow stemmed plants, such as coneflower, and some species of sedum can also provide a place for bees and other insects to overwinter or lay eggs, so consider leaving the stems of these plants intact for the winter. Seed heads of these plants can be cut and left on the ground for the birds, while the inside of the hollow stem is then exposed for insects to enter.
Remove diseased plant material
Plant residue from any plant material that was diseased during the growing season should be completely removed from the planting area during fall cleanup. Diseased plant material should not be added to a compost bin, as the pile may not become hot enough throughout the pile in order to kill the pathogens responsible for the disease. Diseased plant material should be discarded in household trash.
With a little extra effort this fall, environmentally conscious gardeners can have both a thriving landscape next spring as well as a landscape that provides critical ecological benefits for the environment.