Greens till in about as easy as any cover crop I have used.
About any type of pea will till in better if it is mowed first. Turnips have been my worst cover crop. Mustard will produce a lot of top without a lot of root mass. I like grain rye for a cover crop but it is not edible.

Larry

Charlotte, In winter I normally use hairy vetch mixed with rye, or Austrian winter peas with some form of clover. Some years I have used turnips.

Traditonal green peas, whether of the English shelling pea type or the edible podded peas like Sugar Snap peas all suffer freeze damage when temperatures go below roughly 22-25 degrees and aren't a good bet for garden crops over the winter because they will winter-kill without some protection. Even with protection, if the temperatures drop low enough, they'll freeze and die. Some people grow fava beans as an edible fall/winter cover crop, with mixed success in terms of whether or not the beans produce an edible harvest. Still, the plants are pretty cold-tolerant (roughly the same as peas) and as a legume they would be good soil-builders.

I like sowing lots of lettuce, mesclun mix, mache, spinach, Swiss chard, kale, sorrel, collards, mustard, beets and turnips. We eat what we can and let the rest serve as a cover crop or a supplement to the chickens' winter diet of grains. I like to sow lots of extra greens (apart from the ones planted specifically for us to eat) so I can harvest them using the cut-and-come-again method and throw handfuls into the chicken runs every day. I've really filled the beds this year with lots of kale and collards because they are very winter hardy, and the mustard plants I use (Ruby Streaks and Giant Southern Red Mustard) are highly ornamental as is the kale. My goal with winter crops first and foremost is to get something edible, but secondly to have something growing to prevent erosion. It helps if they are crops I can rototill into the soil, but if they are too big and cumbersome for that, I yank them at planting time and feed them to the compost pile. Beauty matters....hence all the flowers and the ornamental cabbage and kale.

Some years I sow radishes and carrots as cover crops to hold the soil in place. I often plant parsley in winter too which allows it go get big and well-established by spring. We don't necessarily get a harvest from the radishes and carrots (sometimes we do, it depends on the weather) but I like to leave them in place and let them flower in the spring because their flowers attract beneficial insects. I generally sow seeds of chives and onion chives in fall and seeds of bunching onions too. Cilantro is a great cool-season crop as well. While all these are planting more for eating than for use as a cover crop, they also hold the soil in place to prevent erosion, which is one purpose of a winter cover crop.

One of my all-time favorite winter cover crops is the various varieties of ornamental kale and ornamental cabbage. They look beautiful, help hold the soil in place and can be cut or pulled and either put on the compost pile or rototilled into the ground. If you are going to use ornamental kale and cabbage, they're easier to deal with in spring if you pull them and compost them when they're done, making them more of a compost crop than a green manure crop. In order to work them directly into the soil, you have to chop them up into smaller pieces first.

You also can sow winter wheat, but that doesn't give you an edible crop--it does give you lots of mass in the spring.

For pretty cover crops to hold soil in place and prevent erosion, I often plant pansies and violas, and we have Laura Bush petunias, poppies and larkspur in the flower border around our veggie garden. They usually reseed themselves and sprout sometime in fall or early winter. This week, I noticed the poppies and larkspurs already are sprouting. The current Laura Bush petunias have been growing since last winter, and they'll often stay green and in bloom until the temperatures hit the mid-teens. Then, as soon as the weather warms up again, either they regrow from the roots, or new volunteer plants sprout, or both. My garden slopes, so I need to have something growing in as much of it as possible all winter long to reduce erosion.

Successs with cover crops in the fall through early spring is highly dependent on the weather. In a warm to average cool-season, just about any cool-season crop works as a cover crop. In a very cold winter like we had a couple of years back, only the most cold-hardy ones like hairy vetch or Austrian winter peas will make it through the bitter cold. Sometimes winter cover crops do freeze back to the ground on an especially cold night, but then they often regrow quickly.

If you grow lettuce in the winter/spring, if you'll leave it in the ground as it goes to seed, small birds like the goldfinches love the seeds so I like to leave it there for them to enjoy.

Dawn