Winter Cover Crops: The What, Why and When to Plant
What happens in the Stone Barns field when the corn stalks fall, the squash are picked and set to cure and the fall plants are pulled? Farmers plant winter cover crops. Here’s the story of the cover crops we plant, why we plant them, and when we plant them. Hopefully you’ll find a few helpful hints for your own garden or growing space.
Soil is the foundation of a healthy agricultural system. Through crop rotation, nutrient management, and a system that takes into consideration the unique growing environment, our farmers have built the most valuable of all farming tools: soil that is biologically rich. When it comes to soil and the changing of seasons, Vegetable Farm Manager Jack Algiere says he has one rule, “never leave the soil exposed.” Exposure leads to extreme temperature fluctuation, water infiltration, soil erosion, leaching, surface compaction and cracking, and low biological exchange. It can kill your soil. So, instead of leaving your beds fallow, plant a winter cover crop.
There are several types of cover-cropping you can employ: winter crops, winter-kill cover crops, organic mulches like straw, leaf mold or wood chip, and living cover crops. Stone Barns implements all of these techniques.
Winter crops keep a biological exchange flowing, fight erosion, and produce during the lower yield months. Spinach, kale and parsnips grow in the Stone Barns field soil through the winter, sometimes taking advantage of season extension methods like low tunnels.
The winter-kill crop Jack plants is a combination of oat and field pea. In our northeast climate zone, these crops are seeded late in the summer (August through early September) so that they reach maturity before the first frost, which brings on the “kill.” As the season progresses and these plants die, they form a thick mat of protection both above and below the ground. They succeed in holding the soil in place for the season, but will not survive the winter here, and will not re-grow in the spring.
Mulches offer protection to beds that have been prepared for seeding a season ahead of time. Some beds are pulled, tilled and dressed with compost in the spring or summer and are not planted, but are covered heavily with straw mulch to combat erosion. Since it is not certain that the weather and soil moisture level will allow Jack’s team to prepare the ground during the early season of February and March, these pre-made beds can be ready at the first chance for planting without creating more environmental damage or losing valuable growing time.
Living cover crops also keep a biological exchange going between plant and soil, but don’t produce a harvestable crop. Jack primarily plants a combination of winter rye (grain) and hairy vetch (legume). These varieties are extremely cold tolerant and can withstand Stone Barns winters. When the soil is frozen, their growth suspends, and when it is thawed, they grow. These crops are planted until mid to late November, so you gardeners still have time to these covers in.
Utilizing all of these cover-cropping techniques, Jack knows that the biology his crew builds through careful crop rotation is protected from the elements and from erosion, ready to receive seeds for another year of healthy crops. So next time you visit the winter field, keep an eye out for these varied covers. Despite the chilly temperatures, there is lots of work happening both above and below the soil.