The intensity of the gardening year is winding down. Once the harvest slows or stops, many people turn their attention elsewhere. However, you’re not done yet. You need to plant cover crops to protect the soil and keep it active. After all, Mother Nature likes to keep herself covered up. Cover crops are a great way to increase organic matter in your soil. In order to plant cover crops, you need to clean up what has finished in the beds. I prefer to think of it as harvesting the biomass from the spent crops for compost material. Your garden gets cleaned up, compost built, and cover crops planted.
There are many choices for cover crops-crimson clover, hairy vetch, Austrian winter peas, and cereal rye are some of them. If you are tilling everything in the spring, which crop you plant now might not be so important. (It is, actually, if you are planning fertility, but I’m dealing with timing in this post.) If you are managing your garden with hand tools, your crop choice makes all the difference. Knowing what crop will be in each bed next year determines what should be planted this fall.
Think of what time you need each bed ready to plant next year. Some crops can be planted “as soon as the soil can be worked”, which I translate as early March here in Zone 7. Other crops need to be planted only after the last spring frost (about April 26 around here). Then there are the crops that would be planted between those two times. Planning ahead now, you can put in cover crops that will be ready to harvest when the bed needs to be ready for that next crop. Make a map of your garden, showing each bed with the crops for the whole year. What you plant now will be the first crop listed in each bed on your 2013 map (and the last crop in each bed on your 2012 map.)
Thinking of those crops that you will plant the earliest in the spring, peas, lettuce and onion sets come to mind. In those spots, it is best if the previous crop has winterkilled. In that case, the winterkilled cover crop has to have put on all its growth in the fall, meaning it needs to have been planted around the end of August or early September (in Zone 7). I have to admit, I’m a little behind on that myself, and plan to put in some oilseed radish this week. Another choice might be oats. If you want to actually harvest oat seed, it needs to be planted in the spring. The radishes–oilseed, fodder or Daikon–can be harvested for your table for roasting or fermenting until about January 1. Most likely, in Zone 7 and colder, they will die back in January, but if we have a mild winter, like the last one, these crops may need a little help to return to the soil in February. In that case, cut the oats or hoe to chop the radishes and leave everything in place. If you miss your window of opportunity for planting and want to do good things for the soil, plus have it ready for the next crop on March 1, mulch that space with leaves. Pull them off a couple weeks before you want to plant the early spring crop to allow the soil to warm up.
Austrian winter peas is my crop of choice to precede things that I will plant in early April. It is too short to pull out on March 1, but has put on some growth and made the soil quite nice by April 1, when I normally plant my potatoes. I put the biomass from the winter peas in the compost. It is also the legume that can be planted the latest in the fall and still make a good crop. Planted in early September, it will grow a lot in the fall and maybe even flower. If that happens, it will most likely winterkill. Planting it in October insures that it will be a nice green cover through the winter.
The legumes are easy to pull out or cut if you need the bed sooner than expected, and the soil is wonderful and ready to plant in, with minimal preparation. Other legume choices, besides winter peas, are crimson clover and hairy vetch. I might plant those things in the beds that I will plant a main crop in about the end of April, after the last expected frost. For any of these cover crops, it is to your advantage to leave them growing until they are flowering. At that point they have put on their most growth in biomass, both above and below the ground. In addition, the flowers provide nectar to the honeybees and other beneficial insects. The clovers and vetches do best if they are planted in September or early October here in Zone 7. If you are running late with your fall planting, you can go ahead and put them in and see what happens, but know that an early frost or harsh winter might set them back.
So far, the choices I’ve mentioned are legumes. The real soil builders are the carbon crops, particularly cereal rye. You are going to get the most biomass from the roots with cereal rye, sometimes referred to as winter rye. This is different than ryegrass. What you want looks like wheat seed, not grass seed. If you talk to gardeners with tillers who have planted rye, they will tell you that it is important to till it in early because of the mass of roots that need to be churned up to decompose. If you are managing your garden with a tiller, that is good advice. If you wait past mid-March, the rye will be so thick, above and below the ground, the tiller would have a hard go of it. With hand tools, however, we are gardening smarter, not harder. I consider rye to be an important soil building and compost crop, so I’m not in a hurry to take it out. I want it to express itself as much as possible. If I let it express itself all the way to seed, it will be mid-June before the bed is ready for the next crop. At that point, I will have rye seed to eat or plant again in the fall (after I thresh it out), and straw for compost building. The plant will be finished, and even though you will see stubble in the bed after the crop is cut, you will be able to easily transplant into it or run a hoe through it to make furrows for the seeds of the next crop. Leave the stubble there and it will slowly compost back into the soil. Removing the stubble would be unnecessary work. If you were growing wheat to eat, which I highly recommend even if it is a small amount, you would manage it the same way.
Where I need the benefits of the cereal rye, but want to get the next crop in before mid-June, I’ll cut the rye at pollen shed, which is about May 7 here. That’s when it is flowering, which is the point of the most biomass. If it is cut earlier, the plants will grow back, trying to get to that seed stage. When it is shedding pollen, it is already thinking about going to seed. The roots, however, will be a mass that will be hard to get my garden fork into, let alone turn over. Of course, I’m not going to turn it over anyway. I cut the rye with my sickle and let that biomass lie there for two weeks to settle. Then I transplant into it, using a sturdy trowel or a soil knife for the job. In this case, the roots are on their way to decay, but there is still a lot there, so you wouldn’t be able to just hoe a row for seeds. This is a good system for transplanting things like tomatoes, peppers, and squash–crops that would benefit from the natural mulch that is just there—you haven’t had to haul anything! If the rye was cut May 7, transplanting wouldn’t take place until May 21.
You can see how all this works in the garden in my DVD Cover Crops and Compost Crops IN Your Garden. I’ll be at the Mother Earth News Fair this weekend at Seven Springs in Pennsylvania. Come to my presentations–Plan a Sustainable Vegetable Garden, Sustainable No-till Gardening, GROW BIOINTENSIVE® Sustainable Mini-farming and Solar Food Drying. Between my talks you can catch me at the Homeplace Earth booth. See you there!