What is Winter Mulch?

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What is winter mulch and how could mulch possibly be beneficial to plants in the wintertime? If you live in an area where temperatures dip below freezing, applying mulch allows plants to “sleep well” through the cold months. Winter garden mulch also helps the soil in many of the same ways that it does during the growing season. There are other benefits, too. Don’t want to buy and haul in bags of mulch? You may already have all the materials you need to produce your own mulch.

The Benefits of Applying Winter Mulch

yellow plastic watering can in a winter border garden coated in a shallow layer of snow
The primary benefit your plants will receive from winter garden mulch is protection from freezing or fluctuating temperatures and icy winds that can damage your plants. A thick layer of mulch blocks out the sun and helps maintain the temperature of the soil. This is important because thawing and refreezing cause soil to contract and expand. That can push your perennials up and expose roots and crowns to freezing weather.
Lonicera caerulea roots exposed above the soil surface caused by soil heaving
When temperatures rise on a sunny day, warming exposed soil and sunshine can trigger dormant plants to awaken. They can begin putting on new growth when they shouldn’t. A layer of mulch helps stabilize the soil temperature around a plant’s root zone to delay it from sprouting until the earth is thoroughly warmed.
As it does in the growing season, mulch helps to keep the soil moist during the winter, too.
Rhododendron shrub by a wood fence in winter with the shrub surrounded by ice and snow
Heavy snows can compact soil around your plants. A layer of winter mulch creates a cushion between the weight of the snow and a plant’s roots. This reduces the chance for soil compaction and improves soil aeration.
Runoff from melting snow and heavy rains cause erosion. Winter garden mulch minimizes erosion.

What’s the Best Mulch for Winter Protection?

Rhododendron shrub in a border next to grassy lawn with pine needle mulch surrounding the shrub
Depending on where you live, the best mulch for winter protection may be what you see around you. Basically, you’re looking for organic materials that are loose, lightweight, and easy to apply and remove. Your mulch material should also provide insulation.
Any of the following natural materials can make good winter garden mulch:
  • Shredded bark
  • Hay/straw
  • Pine needles
  • Sawdust from untreated lumber
  • Leaves
  • Aged compost
Avoid using anything that isn’t organic, like plastic, rubber pellets or natural mulch that has been dyed.

Mulch Before Winter

woman in a winter coat with a wheelbarrow of mulch to put on her winter garden with a log house in the background
You should apply mulch before winter sets in, but exactly when to mulch will depend on what types of plants you’re protecting.
For herbaceous perennials like peonies or woody perennials like rosemary, apply mulch after the first fall frost occurs and the plants begin to go dormant. If you live in an area where the ground freezes, remember that using winter mulch will help keep it frozen rather than allowing it to thaw and refreeze early and late in the season. This allows perennials to remain dormant as they should throughout the winter.
kale, collards, and broccoli plants in a raised garden bed in winter covered by a layer of snow
For annual flowers or vegetables in your garden, you’ll want to mulch early before the first frost occurs. The goal of applying winter garden mulch to flowering annuals or a vegetable garden is to prevent the ground from freezing as long as possible and to protect plants from frost. This allows your garden to continue well into the fall and possibly even into the winter depending on where you live.
This method works well with root crops like carrots and turnips and also with leafy greens like kale. The thicker the mulch blanket, the longer your plants will produce. Cover your garden area completely with lightweight mulch, like leaves or pine needles.

When to Remove Winter Mulch

hand using a small garden rake to pull away winter garden mulch from the base of a rose plant
Wait until after your area’s last frost date has passed before removing winter mulch. For perennials, remove just enough mulch to expose the tops of your plants to the spring sunshine. This stimulates them to come out of their winter sleep and begin to put on new growth. Leave the rest of your winter mulch to decompose and block weeds.
corn plants in a home vegetable garden with sheets of cardboard used to create a mulch
Winter mulch can also be left to decay in your vegetable garden. If you practice no-till gardening, simply move it aside and expose the soil where needed when you’re ready to plant.

Protecting Plants with a Winter Mulch

Lemon beebrush_Aloysia citrodora_emerging in spring through shredded bark mulch
Applying winter garden mulch to perennials is like giving them a blanket to protect them from the cold and help them to remain dormant. As a result, they’ll be healthier and happier come springtime. Covering the vegetables in your garden with a winter mulch before the first frost will allow them more time to produce nutritious food for your family.

Mulching for winter doesn’t have to be expensive. In fact, you may already have a source for all the winter mulch material you’ll need when fall arrives and tree leaves begin to drop. For more information about the benefits of mulch year-round, see our Garden Tips article.

pair of gloves hands scooping a handfull of bark mulch


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