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Homestead Reflections: Early Season Cover Crops

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This article comes from the NOFA/Massachusetts 2018 March Issue Newsletter

By Sharon Gensler, Soil Carbon Outreach Coordinator

Green Cover Crops

Although it is only mid-February as I write this, spring is in the air. I am still hoping for more snow, as I like having the garden tucked in with a nice blanket of snow atop the mulch-covered beds. But alas, the snow is melting fast. Not only does snow replenish soil moisture, but also, its insulating quality helps protect the soil and soil life from a deep freeze. 

I’ve been giving more talks on the topic of Cover Crops/No-Till For The Home Garden: Small Scale Practices for Soil improvement and Carbon Sequestration around the state.  There is a lot of interest in this topic because it is such a win-win for us and for the planet! Healthier soil equals healthier plants, equals healthier food, equals healthier eaters, all while taking excess carbon dioxide from the atmosphere and storing it deep within the soil.

Healthy soil is co-created, with our help, by an amazingly beautiful, symbiotic relationship between plants and soil microbes. There are billions of these creatures (bacteria, fungi, nematodes, protozoa, arthropods and others) in every teaspoon of healthy soil. Through photosynthesis, plants transform sunlight into carbon dioxide, water and glucose, some of which is used for their growth. However, over 60% of these sugars get “dumped” into the soil, becoming food for microbes, that in turn scavenge minerals, trace elements and other substances, making them bioavailable on demand to the plant. The microbes and plants have evolved this complex, mutually beneficial relationship over the eons. This process is also the basis for creating new topsoil and for storing sequestered carbon.  Maximizing photosynthesis by keeping the soil covered with growing plants is key to creating a vibrant soil and to carbon sequestration.

This is a very simplified explanation of soil biology. However, you can immerse yourself in fascinating readings and videos on this topic on the NOFA/Mass website at

I will be discussing soil biology in greater depth over the coming months. Folks have asked me for more specifics of how they can use these techniques. So, even though I have written about cover crops (cc) in this column many times over the years, I’ve decided to write more specifically about how we use them here at Wild Browse Farm. Each month I will describe in more detail what, why, and how I’ll be implementing these healthy soil techniques.

Let’s start with a reminder about the benefits of cover crops. Primarily you are keeping your soil covered with LIVING GREEN PLANTS as much as possible, and in this way you are increasing the amount of photosynthesis generated on the planet. The use of cc’s is a long-term soil improvement technique rather than an instant fertilizer because, in addition to sequestering carbon and feeding microbes, as plants mature and dieback (or are cut back) their nutrients and their biomass are returned to the soil. Cover crops improve soil structure, suppress weeds, control erosion, increase water retention, create biomass, and help with pest and disease control.

So, it’s March and a bit early to work the soil, but not too early to plan for April. As part of ordering my vegetable and cover crop seeds back in January, I planned how much of each vegetable would be needed for the year and how much garden space would accomplish this.

Over the years, as our soil has become healthier and more productive, and with each plant having a higher yield, I have been able to cut back on the amount of space I really need for planting vegetables. Thus I have “extra” space available to use for cc’s, either for whole or for part of the growing season. For example, if I know that I can spare a whole growing bed for the entire season, I can plant it entirely in a cover crop. Or, because I know where my heat-loving veggies (tomato, pepper, eggplant, squash, beans, etc) will be planted, I can plant an early cc in their designated beds until the soil warms and that space is needed for mid-season crops.  

Another way to use cc’s is to plant them later in the season, after removing the primary vegetable. An example of this is to plant cc’s after removing spring greens or again a little later, after garlic. Additionally, cc’s can be planted beneath taller vegetable plants or used to cover spots of any bare soil throughout the garden.

I want to encourage you to incorporate the use of this beneficial technique; thinking ahead about how you might use some cover crops this year is important.  There is still time to plan and to order appropriate seed.

Frost Killed CropsI choose to plant almost exclusively cc’s that are killed by winter’s cold temperatures. By doing so, come spring, there isn’t any potentially “ invasive” cover crop to kill or till under. Instead there is a bed covered in “free” mulch, which has been protecting and feeding the soil throughout the previous growing season and winter months. Oats, field peas, forage radish, buckwheat, barley, sorghum/Sudan grass and sunflowers are my recommendations for cc’s which winter kill here in Wendell. It would be good to check your specific winter temperatures (you’ll need several days/nights in the 20s) to make sure that whatever covers you choose to plant will winter-kill.

Next month I’ll describe how to plant early cc’s, depending on weather conditions, in mid- to late-April. So be sure to have some of the more hardy seeds, oats, peas, and radish ready to plant.

Spring MulchI’ll end with some enticement to get you committed to the miracle of cc’s. Here’s what to expect in the spring from a late summer/fall planted cc. A bed thickly planted in cc in August-mid-September will have a large standing biomass by the time it is killed later in the fall. A bed with a 3- or 4-foot tall cc will die back to 6 or more inches of mulch. By spring this will have decayed to only an inch or two covering an incredibly friable soil, which is ready for planting.

Have a great time planning and thinking of ways to incorporate cover crops in your garden.


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