Cool Season Cover Cropping

Howdy folks, it's early spring here at Route 64 Sacramento and we are ready to turn in some of our overwintered cover crops. Cover crops are an important source of fertility and organic matter here on our market farm, helping us to build and maintain healthy productive soil year after year. We have developed a simple method for establishing stands like this with minimal input and zero soil disturbance, which we hope you find helpful on your own farm or in your garden. It all started last fall as we phased out our 2025 production season and began to prepare for 2026. Here in Sacramento we generally sow most of our winter cover crops in mid to late October and finish in early November. Small delays in sowing result in a much less vigorous stand as it quickly gets too cold and dark for optimal plant growth. A quick turnover of summer crops that are no longer earning their space in the garden is wise. A strong cover crop is worth missing out on those last few straggler tomatoes. So now that we've taken full advantage of the 2025 season and most summer crops are no longer producing well, it's time to sow our cover crop. Some crops might not leave much residue behind and you might be able to sow directly, while others will leave large unwieldy plants. In this case the flail mower is an ideal tool to finely chop up the residue and return the organic matter to the soil. If you do not have access to a flail mower, you may lop large plants at the base and move them to a compost pile or into the neighboring path to use as mulch. But if you are able to flail mow, this is the quickest and most effective and labor-saving way to return the nutrients from your crop plants back into the soil. The flail mower leaves finely chopped up residue on the surface of the soil trapping moisture and facilitating quick decomposition. We will be leaving this residue in place and sowing our cover crop seed right on top of this layer. Now that our bed is ready to be sown, we're going to pull out our seed. For winter cover cropping we typically use the premium organic soil builder mix from Peaceful Valley Farm and Garden Supply in Grass Valley. This blend includes a mix of several species of nitrogen-fixing legumes including bell beans, field peas, and vetches, as well as oats, which grow quickly producing abundant biomass both above and below ground. The word biomass refers to the amount of organic plant matter. High biomass cover crops shade the soil, outcompete weeds, and after they are terminated decompose back into the soil feeding soil organisms and contributing to long-term soil health. All right, back to our premium organic soil builder mix. We weigh out about 1 to 1 1⁄2 pounds of dry seed per 90 foot bed on our farm, equivalent to about 4 pounds per 1,000 square feet. This will vary depending on the seed blend you are using, but the label should have a seeding rate which you can use to help figure out how much seed you'll want to use. When we are sowing using this particular method, we actually like to soak the seed first. Soaking is only recommended if you are sure that you are going to be able to sow within about 24 hours. Soaking is also only recommended if you are spreading and covering the seed by hand. You will not want to use a mechanical seeder or any other sort of equipment with soaked seed. However, if you do not soak the seed, you'll likely need to water more than once after sowing in order to ensure good germination, and it will take an extra day or two for the seeds to come up. So, after soaking from anywhere from about 6 to maybe 24 hours at most, overnight would be typical for us, you'll want to drain your seed, ideally using a colander. Once your seed is drained, you can sow right away or wait another several hours if needed, but you don't want to wait too long because these seeds will start to germinate within another day or two if left in the bucket, and the emerging radicals can rot, dry out, or get snapped off. Before you sow cover crops with legumes, that is any sort of pea, lentil, vetch, or bean, it is recommended to inoculate the seed. You'll have to buy an inoculant, which is essentially a probiotic for your soil. The inoculant will include the bacteria that the legumes need in order to fix atmospheric nitrogen into a form your future crop plants can use, thereby maximizing the fertility benefits of your cover crop. Now, since we soaked our seed and it is wet, we don't need any additional water, but if you are starting with dry seed, you'll want to add just a few tablespoons of water, maybe even less, just enough to moisten the exterior of the seeds. After stirring the seeds thoroughly in order to make sure that they're all moist, then you can stir in your inoculant as well, mixing until you have evenly coated all of the seeds. After your seed is coated with inoculant, you might want to divide it to make sure that you get even coverage. Here, for example, we soaked enough seed for four beds, so we are using a scale to split the seed four ways to make sure that each bed gets enough seed. Of course, the soaked seed is much heavier than the original one and a quarter pound per bed that we soaked, so we want to make sure to take that into account. Next, we head out to the field and sprinkle the seed onto the bed, getting nice even coverage across both the length and the width of the bed. Start lightly to make sure that you have enough seed to cover the full bed. You can always circle back and spread the rest of the leftover seed at the end. Next, you'll cover the bed with compost. About an inch is plenty. You don't want to smother the seed. Again, start lightly and circle back to apply more where you need. With this style of cart, there is always a large pile at the front of the bed, so generally I leave the first few feet of the bed uncovered and use my feet or a rake to spread out that pile once the rest of the bed is covered adequately. Once your compost is spread, the final step is to water the cover crop in. Since the seed is soaked, you'll need to get to this right away. We use these simple mister sets that we built in order to irrigate one bed at a time. We will run these misters for about an hour or two over wet soils, or as much as six or eight hours if the soil underneath is very dry. You'll want to water thoroughly and deeply so that the roots of your new cover crop will have moist soil to grow down into. If your seed is not soaked, it's not as urgent to water it in, and maybe waiting a day or two for rain could be fine, but again the seed might need some extra watering and some extra time in order to germinate. In the case of our soaked seed, if the weather is warm, a few days after sowing you'll be able to dig down into the compost and see the seeds starting to germinate. And here we have our cover crop on day 10, three weeks after sowing, and a month or so after that you'll have a strong stand of cover crop protecting and feeding the soil. By spring your cover crop should be several feet high and beginning to flower. At this time you'll want to start to think about terminating your cover crop, which we will be covering in our next video. If you dig down into the soil at this time you'll hopefully find these round nodules on the roots of your fava beans, peas, and vetch. These nodules are where the rhizobia, or nitrogen-fixing bacteria, reside. These bacteria are what allows the cover crop to fertilize the subsequent crop, and ensuring their presence on the roots was the reason we added the inoculant to the seed before sowing. On a farm, as in nature, diversity is important for adaptability and resilience. The diversity of species within this cover crop blend helps extend the flowering season, which of course helps feed our resident beneficial insects, and also extends the termination window for the crop. The different species also host a diverse array of microorganisms within the soil, increasing resilience underground, and structurally the different plants benefit each other as well. Oats, which grow strong vertically, act as a scaffold for the vining vetches and peas. Like other cereal grains, oats are a grass, and grasses have an especially extensive and fibrous root system, which help to stabilize the soil against erosion and also improve soil structure, just as those legumes are providing the nutritional benefits your crops will need to thrive. And that's it! Grow a lush cover crop, and your soil will surely thank you in the spring of bountiful harvest.