Friday of last week, I put down winter rye seed for a cover crop. Look how well it is doing already. Warmer than average temperatures hasn't hurt, but good management practices is the key. Night time lows have been between 31-38 degrees for the last week, but winter rye doesn't mind that much. It is pretty hardy, so as long as you can keep it wet and you don't have a hard freeze, it will germinate. A trick that Joe Scherber taught me is putting clear plastic over the planting area to get it to warm up a little more. It also helps keep the moisture in, which makes a big difference. Pre-germinating indoors in a bucket of sand with a little kelp and humic acid also helps ensure a higher germination rate. These grass blades are already about 2 inches high, which is pretty amazing a week after sowing the seed.
In the spring, that grass will take off when it gets warm and grow like crazy. I'll till it into the soil as a green manure to increase the organic matter in the soil and then I'll plant another cover crop of winter rye in the patch, except for the planting areas, at that time to help suppress weeds, keep the soil from getting compacted, help get the biology going in the soil and add additional organic matter. When the pumpkin starts to vine out, I'll till in that 2nd cover crop well in advance so that it will be broke down in the soil by the time the roots and vines get out that far.
I really like winter rye because it establishes well in the fall and it is easy to get rid off when it is time to till it in. You can fairly easily just pull it out of the soil in your hand, which is great, because you don't want to have to fight it off like a weed after establishing it.