Winter Cover Crop: Why You Should Copy This Farm Trick

A winter “cover crop" isn't just a big farm thing. When I first heard of it I figured that was for the farmers riding tractors and hauling in bales of soybeans. Or is it bags of soybeans? A cover crop sounds so official. Way more official than our two little nine-foot raised beds.

But hey, it turns out that a winter cover crop works for tiny urban gardens too! After reading up on cover crops, I started thinking of it as a fun way to play with garden through late fall and winter.

The fun part is you're still growing some little plant babies after you pull everything else out. The practical part is that a cover crop helps the rebuild the garden's soil structure after summer's ravages. A cover crop also chokes out weeds and covers up the garden so there isn't any bare soil to blow or wash away.

So, I've now got a winter cover crop covering my urban garden. Here’s how it works.

What winter cover crop to grow

I ordered rye and hairy vetch seeds from Southern Seed Exchange. I love those guys. Based Virginia, they sell heirloom seeds that work well for my area, and have helpful tips and other resources for Virginia gardeners. Plus they make me feel like a serious gardener because they use the word "crops" like they don't know I'm farming a city backyard. Southern Seed Exchange recommends combining rye and hairy vetch, so that's what I ordered.

Here's how they work together: The hairy vetch (don't you want to giggle saying that name?) puts nitrogen back into the soil. The rye puts in deep roots that hold the dirt in place and choke out the weeds. The notes on the rye packet said to mix the rye and vetch in a 4:1 ratio, so I did, because sometimes I follow the rules.

Some gardeners use cover crops during the growing season, sprinkling them in between plants that have died or finished producing. That's a bit different than wintering over - you'll want to choose a different cover crop if that's your goal. More on that in another post.

Here's how easy a winter cover crop is

• Wait until your summer veggies are done growing

• Mix together the rye and hairy vetch in a little bowl

• Pull out the summer "crops"

• Fluff up the soil a little bit with a rake or your hands

• Broadcast the seeds across the bed by sprinkling them around loosely and pressing them down

• Water daily, and by day four they should sprout

• Let them just grow like little beneficial weeds

When a winter cover isn't a crop

Our beds actually have two kinds of covers now. In September, I also planted a few Brussels sprouts, collards and arugula. I want these cold-weather plants to winter over in my mid-Atlantic zone 7a climate, but I don't have a greenhouse. Instead, I'm trying row cover.

We are in the city, so a bit more protected from wind and cold by things like buildings and lots of warm asphalt and brick. This means I don't need quite as much protection as suburban gardens. I ordered some lightweight cover cloth to help protect the vegetables and cover crops, and I'm draping this directly over the bed to keep it 5-10 degrees warmer than it would be uncovered.

So far, everyone is happy. In fact, the cover crops are so happy that they're shoving up a bit too close to the Brussels sprouts and collards. I may have to do a little cover crop weeding. But in spring, everything I plant will be happy.