Why You Should Keep Your Garden Covered For Winter

Crimson Clover Cover Crop

Nature dislikes an empty space, and your soil communicates loudly, often through the language of weeds. If left exposed, it will react by flourishing with thistles, pigweeds or other common garden invaders. 

Leaving your soil uncovered during the winter is not a great option. The elements including wind, rain, and cold, will harm the valuable topsoil layer, causing a loss of nutrients and structure, leading to erosion. Therefore, as your garden finishes up for the season, if you fail to provide a protective layer, nature will step in, using weeds to perform the task.

There are various options to cover the soil, including mulches, cardboard, or black plastic, but the most effective choice by far is plant life. Strong evidence supports the idea that actively growing plants maintain a healthy and resilient food web beneath the soil surface. This is why, in the absence of intervention, the soil tends to favor weeds.

To avoid the less than desirable task of constant weeding, an excellent alternative is using cover crops (also known as green manures). These rapidly growing crops cover the ground, outcompete most weeds, and contribute to soil building while protecting it from erosion. Cover crops also retain nutrients that might otherwise be washed away during fall and winter rains. In spring, the cover crop can either be left on the surface or incorporated into the soil through digging to decompose, releasing nutrients back into the soil for the next crop. Plant residues can also be raked off and composted before adding back to the soil later.

For winter protection, cover crops should ideally be planted at least 4 to 6 weeks before typical growing conditions turn too cold for plants to thrive. In colder regions of Canada, this means typically planting by the middle of September. For milder regions like Southern Ontario and Coastal British Columbia, many cover crops can be planted well into October. 

 Preparing Garden Soil

After harvesting a crop, level the ground with a hoe and replant with a cover crop of your choice. For late summer, two primary types are recommended. The first category comprises fast-growing plants that are not freezing-resistant and will be naturally terminated by the first hard frost. The deceased stems and leaves are intentionally left in place to provide additional protection to the soil, and worms will integrate them by the end of spring. Typical examples include buckwheat, daikon radishannual ryegrass and garden mixes that include oats. Simply scatter the seeds, rake them in, and allow nature to take its course.

The second type involves perennial clovers or grasses such as perennial ryegrass, which can be planted either in spring or during fall. They can be left for up to three years as a prolonged cover crop solution (ideal for pathways). Clovers, recognized for their nitrogen-fixing root nodules that enrich the soil and effectively suppress weeds, offer versatile options. Alsike clover is suitable for wet and difficult to grow soils, crimson clover is well-suited for dry and light soil; and white clover, adaptable to high traffic areas.

Cover Crop Garden Bed
Garden bed planted with crimson clover and buckwheat cover the ground 4 weeks after planting

Whether tending to container gardens or open soil, cover crops offer a chance to protect and improve our soil health. By incorporating these resilient allies into our gardening practices, we not only enrich the soil with nutrients but also create a natural defense against weeds. Cover crops are easy use and a natural choice for growing more ecologically minded gardens. 

For more information on cover crops, visit our other Cover Crop articles.

About the Author: John Côté owns and operates John Boy Farms with his family who have been farming the same land for over 140 years. As an agronomist and experienced farmer, he helps others learn how to grow garlic and cover crops successfully. He has written many articles and is the author of The Master Guide to Growing Big Garlic.