I’ll often hear people say that they clear their garden beds in the fall to tidy things up for winter. But in truth, there are many good reasons to leave garden debris in place over the winter months.
Leaving dead plants in the garden over winter provides many benefits, such as creating winter shelter for pollinators and beneficial insects for hibernation. Fungal networks use root systems to survive until the spring, and residual organic matter benefits soil texture as it decomposes.
So next time you’re tempted to tidy up your garden beds in the fall, remember that nature knows best. Leave the debris in place and let it do its job.
Check out this episode of my podcast, Organic Gardening For Beginners, where I also chat about leaving dead plants behind as part of your winter prep.
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Why should I let dead plants overwinter in my garden?
There are many good reasons to leave dead plants in your garden over winter. Dead plants provide shelter for pollinators and beneficial insects, help support fungal networks, and improve soil texture as they decompose.
Additionally, allowing dead plants to overwinter in your garden can help prevent erosion and reduce the amount of work you have to do come spring.
Provide pollinator and beneficial insect housing
For one thing, many insects use old stalks and leaves as housing. Plant debris, brush piles, and leaf litter are especially beneficial for pollinators like bees and ladybugs, which can’t survive the cold winter months without the right shelter.
Bees: There are 4,000 known native bee species in North America alone. Unlike their honeybee cousins, most of these species don’t form hives, instead relying on their environment for housing.
This is where your garden comes into play. Native bees require the right environment to protect them from winter conditions. Keeping these guys around is to your benefit. Just two native bees (mason bees specifically) can pollinate as many flowers as 100 honeybees!
Now let’s talk about how to provide suitable materials for their homes. The Xerces society explains that different bees like different styles of houses. Provide plants with hollow stems like raspberries, roses, or bee balm to accommodate as many bees as possible.
At the end of the growing season, leave old flowers and dead plant stems as a shelter for insects. Only clip dead material in the spring – but don’t clip them to the ground. Try to keep stems between 8 – 24 inches long. Diversify the length to provide a range of options for various insects.
Ladybugs: Ladybugs are predatory insects, eating pesky aphids and scales. Home gardeners sometimes purchase kits with live, mature ladybugs to release into their garden, hoping they’ll stick around and feast on the pests they find.
Unfortunately, most of those ladybugs will fly away immediately, never to return.
A better solution is to create an environment in which local ladybugs would love to overwinter. Leaf litter, rock crevices, and bark or wood chips are all excellent options. By leaving dead plants and mulch in your garden until next season, you’re creating the perfect shelter for them.
Other beneficial predators: Beyond ladybugs, many insects help keep pests off your plants. These insects favor the same conditions that bees and ladybugs use to overwinter. Leave hollow-stalked plants standing throughout the winter, allow leaf litter to collect, and have some bare soil, bark, and rocks in your garden.
Some of the beneficial predators who might make a home in your garden are:
- Soldier beetles
- Ground beetles
- Tachinid flies
Create a winter buffet for birds
Some gardeners may be tempted to cut the stems of perennials and old annuals in the flower garden in the fall. But sunflowers, black-eyed Susans, and other native wildflowers produce a valuable food source for birds with their seed heads.
Other birds may use the dried stalks or seed heads to build their nests or weave nesting material into existing structures. And some, like finches and cardinals, will appreciate the protective cover that dead plants offer from predators and cold weather.
Leaving dead plants in the garden also helps create protein-rich snacks for overwintering birds. As the plants die back, they become hosts for many beneficial and harmful insects.
Birds won’t discriminate when foraging for insects. If you’re lucky, they’ll snag a grub from the soil and take it back to their nest to feed their young. If you’re less fortunate, the birds will snatch wasp larvae that would otherwise grow up to be excellent pollinators.
You win some, you lose some.
Protect beneficial fungi within the soil
You now know the aboveground benefits of overwintering. It’s time to talk about the underground organisms that benefit from garden debris – specifically, dead root systems.
There are millions of species of microorganisms living in the soil. Some of the most beneficial of these microorganisms are mycorrhizal fungi.
Mycorrhizal fungi inhabit plant root systems. They exchange resources such as nutrients and water for sugar. Regular plant roots only come into contact with 0.5% of topsoil, which means that most of the nutrients and water in the soil are out of reach without mycorrhizal fungi.
The smaller roots of the fungi are threadlike and can pick up much larger amounts of nutrients, which improves the growth of the following crops. The improved nutrient uptake allows plants to survive droughts, grow better, and even overcome soil-borne diseases.
However, it can take a while for these connections between plant roots and mycorrhizal fungi roots to form.
Suppose old roots remain in the soil and new crops are planted in their midst. In that case, the awakening fungi can attach to the new roots, continuing the beneficial relationship in undisturbed soils.
For tips on planting around old garden debris, check out this article: Should You Remove Old Roots Before Planting? (Nope, Here’s Why)
Improve soil texture and increase organic matter
Another benefit to keeping previous crops over winter is increased organic matter, which improves soil texture.
Plant roots stretch deep into the soil. After plants die, their roots decompose and create chambers in the soil, allowing water and air to infiltrate more easily. Nutrients from the roots will remain in the soil for other plants. Building organic matter is also a great way to improve water retention in soil, so you’ll have to spend less time watering next season.
Usually, you would need to add compost or manure to the soil to build organic matter, so by leaving plants behind to decompose in place, you’re essentially creating a compost pile right in your garden.
Are there any problems with allowing dead plants to overwinter?
The potential problems with overwintering are primarily due to the fact that it can increase pests and diseases. However, these problems should be minimal if you have a healthy, diverse ecosystem in your garden.
Overwintering pest and disease
Unsurprisingly, the same habitats that host beneficial insects and fungus can also host the bad ones. With this in mind, it sounds counterintuitive to allow overwintering sites. In fact, many garden experts will tell you that you shouldn’t leave any garden debris for that very reason.
However, the Xerces society explains in their book, Farming with Native Beneficial Insects, “the benefits of habitat on farms for natural pest control generally outweigh the downsides.”
Added habitats will allow the population of natural predators to grow and be ready to combat early-emerging pests in the spring.
How to combat any negative effects
To combat the negatives of allowing your plant debris to overwinter, rotate crops annually. This practice can help with diseases and keep pests in check that require a particular host.
Rotating crops means planting a different crop in the same spot each year. For example, if you have a problem with cucumber beetles, you might consider planting something else in that space next season, such as cosmos flowers, which aren’t bothered by cucumber beetles.
Removing the preferred host plant will decrease the survival rate of pests that overwinter in your garden.
In addition, you can add native plants to your garden. Native plants usually don’t have the same predators as your crops and are an excellent habitat for beneficial insects.
Growing various crops will also aid predatory insects by allowing multiple kinds of prey to exist simultaneously. If there is only one kind of prey, perhaps aphids, then when the aphid population is low predatory insects may migrate to find food elsewhere.
Let your garden settle into winter
You now have the perfect reason to let your garden settle into winter without worrying about cleaning up every old plant. Doing so creates a habitat for beneficial insects to thrive, allows fungal networks to survive the winter, and improves your soil structure for the next growing season.
It may take a little extra planning at the beginning of the growing season, but the benefits of overwintering are worth any inconvenience.