Leave It or Clean It? A Guide to Cleaning Up The Fall Garden
When cool weather and short days cause leaves to drop and plants to fade, many gardeners grab their tools and start cleaning up the fall garden. But is this necessary? Join gardener Briana Yablonski to learn which materials you should leave and which you should remove.
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Finally, cooler and shorter fall days are here! If you’re anything like me, they serve as a welcome reminder to slow down. With spring days spent pulling weeds and summer days spent watering behind us, we can take a deep breath and enjoy everything the past growing season provided. However, it’s not necessarily time to step away from your garden entirely—cleanup still lies on the horizon.
However, before you grab your rake and clippers, take a minute to think about whether you need to remove material from your garden. Do those leaves really need to go into a plastic bag on the curb? Can you leave those old aster stems without worry?
Fall cleanup is often a balance between maintaining a clean, healthy garden and supporting a vibrant ecosystem. I’ll go through a list of common garden materials and cover whether you should leave them or clean them.
Fallen Leaves
Leave it.
In the past, crisp autumn days meant spending the afternoon raking leaves and stuffing the crunchy piles into trash bags. However, there’s no need to spend your time and energy removing leaves from your garden!
Fallen leaves are sometimes known as nature’s gold thanks to the many benefits they provide to soil and crops. Here are some of the benefits of leaves:
Increase Soil Organic Matter
The carbon-rich leaves help feed beneficial soil microbes that improve plant nutrient uptake and help fend off plant diseases. The increased level of organic matter also improves water infiltration, leading to less runoff and flooding. Plus, it helps improve soil water-holding capacity and plants’ abilities to tolerate drought.
Essential Nutrients
Fallen leaves contain numerous nutrients that plants need to thrive. These include nitrogen, phosphorus, and potassium. Leaving leaves in your garden means you can skip or decrease fertilizer applications.
Mulch
When you apply leaves or leaf mold to the soil surface, they act as mulch. This mulch prevents weed growth, conserves moisture, and limits erosion. Plus, using leaves as mulch means you don’t have to spend money on other materials.
Feel the Need to Rake?
If you don’t want a layer of leaves to smother your grass lawn, you can rake them off the surface. However, don’t bag them and place them on the curb! Instead, move them to your garden beds or pile them up near the base of trees and shrubs. They’ll act as mulch over the winter while preventing erosion and weed growth.
Another option is to put the leaves into your compost pile. Shredding the leaves with the help of a mulching lawn mower will speed up their breakdown, but you can also put entire leaves in the pile. Over time, the leaves will turn into a rich leaf mold that increases organic matter content and supplies essential nutrients.
When you’re collecting this valuable material, keep in mind that some trees produce leaves that are harmful to other plants. Species including black walnut, butternut, and shagbark hickory produce a compound called juglone that inhibits plant growth. Therefore, you should avoid mulching with these leaves until they’ve had a chance to break down first. These are better for composting as it takes a few months for the allelopathic compounds to break down.
Help Out Insects
Although fallen leaves may look dead, they often contain diverse life forms! Many insects spend the winter in leaf litter and come to life the following spring. If you remove the leaves from your yard, you risk harming these valuable and beautiful insects.
Butterflies and moths including luna moths and swallowtails overwinter in leaf litter as chrysalises. Other species, like the great spangled fritillary and Isabella tiger moth (the adult of the wooly bear caterpillar), spend the winter as caterpillars. They rely on the insulating leaf litter to remain protected from harsh winter conditions.
Old Perennials
Leave it.
Most flowering perennials complete their life cycle by mid to late fall. Their colorful blooms fade and are replaced by seed heads that will produce the next generation of plants. When you think about it this way, it’s easy to see why you would want to leave this debris in your garden. However, the brown sticks covered with scraggly flower heads and crusty leaves sometimes cause gardeners to think otherwise.
Not only will these seeds help produce new plants, but the old stems and seeds are also crucial for wildlife. Fall-blooming perennials like asters, sunflowers, rudbeckia, coneflowers, and goldenrods provide fat-rich seeds that help support birds throughout the fall and winter. That’s why you’ll often see finches, chickadees, cardinals, and other seed-eating birds hanging out in wildflower meadows and gardens in late fall and winter.
Many of these perennials also contain hollow stems that provide important habitat for insects. Carpenter bees, small yellow-faced bees, and leaf-cutter bees use the hollow stems to form their nests. Since different species prefer various stem widths, planting and leaving a diversity of stems will help these insects thrive.
If you can’t help but tidy up the appearance of your garden, cut the old flower heads with a pair of clippers. Leave about a foot of stem to help support cavity-nesting insects, and place the flower heads in a pile. Birds will still be able to feed on the seeds, and you can enjoy the appearance of a tidy garden.
Diseased Plants
Clean it.
Leaving plants in your garden increases soil organic matter and provides habitat for wildlife. However, leaving diseased plants can wreak havoc on future growth.
Pathogens including cucumber mosaic virus, downy mildew, and anthracnose overwinter on plant tissue. When warm conditions arrive the following spring, the pathogens infect new growth and start their life cycle all over. While many pathogens can also survive the winter in the soil, removing infected plant material will limit the chance of spring infection.
After you remove diseased foliage, avoid placing it in your compost pile. Many pathogens will survive in home composting systems and reinfect crops when you spread the compost on your soil. Instead, dispose of these infected residues in the trash or burn them.
Healthy Wood
Leave it.
While you may want to prune your peach trees and hydrangea bushes in the fall, don’t do it! Pruning healthy branches in the fall can expose them to harsh winter conditions.
Pruning often encourages plants to send up new growth—that’s one reason why it’s helpful for flower and fruit production. However, when you prune in the fall, you create tender new growth that’s more susceptible to cold damage. If this growth dies over the winter, you’ll be left with a weaker plant the following spring.
Fall pruning also creates open cuts that are susceptible to disease. Since they are busy preparing for winter, woody species don’t have excess energy to put towards healing. Therefore, pruning cuts remain open and exposed to pathogens.
Dead and Diseased Wood
Clean it.
Late winter is the best time to prune many woody shrubs and trees. Pruning in the fall can cause plants to put on new growth that’s susceptible to winter damage. Plus, plants often have a difficult time healing before winter arrives.
However, though you should avoid pruning living tissues, you can remove dead wood in the fall. Removing these stems and branches in the fall will prevent them from falling during winter storms. It will also prevent diseases from overwintering in the dead wood.
Before you prune, ensure the branches are dead rather than dormant! Dead branches will break rather than bend, and they lack tender green buds and a green cambium layer under the bark.
Fallen Twigs and Branches
Leave it.
It’s normal for trees and shrubs to drop a few branches throughout the year. Rather than picking up these sticks and placing them on the curb, leave them be! These objects provide habitat for critters, ranging from small insects to larger songbirds and frogs.
If you want to clear your lawn or garden of large branches, don’t remove them from your property. Instead, pile them up near the corner of your garden. This pile will serve as a welcome enclave for birds and small mammals during winter storms.
While leaving these twigs and branches is often the best practice, you should remove diseased materials from your property. This will help prevent the disease from spreading to healthy crops.
