Dirt Cheap: Cover Crops That Actually Do Something While Your Garden Sleeps

Last October I pulled my tomato plants, looked at the bare raised beds, and just… left them. All winter. Figured the rain would handle whatever needed handling. By March I had a nice crust of compacted nothing with some moss starting to move in like it owned the place.

Turns out bare soil in the PNW winter is kind of a disaster in slow motion. The rain hammers it, the structure breaks down, and whatever nutrients were in there either wash out or just sit there doing nothing. A neighbor mentioned cover crops somewhere around month four of me staring at my sad empty beds. Cool of him to wait that long.

What You’re Actually Trying to Do Here

You want something growing in those beds from now until spring so the soil doesn’t just deteriorate for five months. Cover crops fix nitrogen, break up compaction with their roots, suppress weeds, and give you something to chop and dig in before your spring planting. The fancy term is “green manure,” which sounds worse than it is.

August is actually a good time to be thinking about this. Some of these crops need to establish before the cold really sets in, and you’ve got a window right now before your summer beds even start clearing out.

The Cheap Options That Work in Zone 8b

Winter rye is the workhorse. Cold-hardy, grows fast, and a one-pound bag from the feed section at Bi-Mart runs about $2.89. That’ll cover more square footage than you probably have. You broadcast it, rake it lightly, water it in, and largely ignore it until spring. Which, honestly, is my preferred style of gardening November through February.

Crimson clover is the other one I keep coming back to. It fixes nitrogen, which means it’s basically fertilizing your beds for free while it grows. And it’s pretty, which my daughters care about considerably more than I pretend to. Seeds at the local farm store are around $3.49 for a packet that covers a 4×8 bed twice over. You can also find it at some hardware stores in the lawn amendment section.

Fava beans are worth mentioning too, though they’re a little more involved. They fix nitrogen like crazy and you can actually eat them in spring before you turn them under. Two crops in one. I tried to explain this to my youngest and she asked if we could grow something else. So there’s that.

The Mix I Use Now

After a couple years of trying things one at a time, I just mix winter rye and crimson clover together. The rye gives you bulk and weed suppression, the clover fixes nitrogen. They grow well together and you don’t have to think too hard about it. I do roughly 70% rye, 30% clover by volume but I’m eyeballing it from a yogurt cup into my hand so don’t quote me on that.

Seed the whole thing at about 1 ounce per 10 square feet. Scratch the surface of your bed lightly first so the seeds have something to grab. Water it in and you’ll see germination in five to seven days if temperatures are still in the 60s, which they should be in August here.

What to Do With It in Spring

Cut it down before it sets seed. Important. Unless you want rye everywhere forever. Then either chop and dig it into the top few inches of soil or let it sit on top as mulch while it decomposes. I do a mix of both depending on how lazy I’m feeling that week. Wait two to three weeks after turning it in before you plant into that bed. Let it break down a little first or your seedlings will have a rough time.

First year I did this I didn’t wait. I planted my lettuce starts directly into freshly turned-under green manure like I was in some kind of hurry. The decomposition process pulls nitrogen away temporarily while it’s happening. Lettuce went yellow and sulked for two weeks before recovering. Lesson learned the medium-hard way. Which, now that I think about it, is how I learn most things out there.

The Part Where I Brag About the Cost

I spent $6.38 total last fall on cover crop seed and covered four 4×8 raised beds plus a 3×12 strip along the fence. In spring I skipped buying a bag of fertilizer because the clover had done most of the work already. That bag of fertilizer would’ve been somewhere around $14.99. I’m not saying cover crops will pay for themselves. I’m saying they definitely paid for themselves.

Your soil is basically working the night shift all winter for free. You just have to give it something to turnip.

Photo by Markus Winkler on Unsplash