How to Use Winter Mulch to Protect Plants in Cold Weather

Annual Crops

Winter mulching of annual crops is primarily done to keep the ground warm and prevent it from freezing for as long as possible, thus prolonging the harvest season for as long as possible.

Depending on your climate, crops, and thickness of mulch, sometimes this process can even allow crops to be harvested through the winter.

Mulch annual crops in the fall before the ground freezes. 

Crops such as carrots, parsnips, turnips, beets, kohlrabi, and kale can often last well into the winter with extra layers of insulation to keep soil from freezing.

In the harsher climates of Zones 1 to 3, crops may need additional protection such as floating row covers, hoop houses, or cold frames to survive.

Check our our best selections for fall crops for more information.

How to Mulch

To prepare annual crops for an extended harvest, cover plants with a one- to two-foot thick layer of straw, leaves, or other organic material before the ground freezes.

Topping the whole thing off with a row cover, old bed sheet, or garden blanket will help hold it all in place, preventing material from blowing away during winter storms.

You can secure the cover with rocks, logs, or garden staples. Also remember to mark your beds with tall stakes, since you may have trouble finding them again under feet of snow!

Tip: Crops like kale and collard greens can be protected by surrounding plants with stakes wrapped in burlap and stuffing the space between with leaves or straw for insulation.

Some crops, such as garlic and certain varieties of onions are planted in the fall for a spring or summer harvest.

Cover these beds with a thick layer of leaves or straw to protect bulbs through the winter.

In spring, move leaves to the side to allow foliage to poke through and reach the sunlight more quickly.

We take a deep dive into using leaves as compost and mulch in this guide.

Fallow Beds

Unplanted fallow beds can be covered over with organic material anytime during the fall.

This will protect bare soil, helping the soil to retain moisture, reduce erosion, and build up nutrients.

So when you go to plant again in spring, the soil will be nutrient rich, healthy, and moist!

Lasagna mulching is a great technique for protecting fallow beds where you are planning to grow nutrient loving annual crops in the spring, or for anywhere you want to improve the soil.

To build a lasagna bed, simply stack four or more layers of organic materials.

Each layer should be a few inches thick. Try to alternate layers of greens and browns material just like you would in a compost bin:

Greens (nitrogen rich material): Aged manure, compost, garden waste, grass clippings

Browns (carbon rich material): Leaves, straw, hay, sawdust, wood shavings

Use any combination of ingredients you have on hand.