Hairy vetch is a hard-working, fast-growing cover crop, adding large amounts of nitrogen into the soil, benefiting the next crop. It grows quickly and densely, smothering and helping to prevent pesky weeds. At the bloom stage, it contributes the most nitrogen and is easiest to incorporate. It biodegrades quickly, needing just a few weeks of rest before sowing your next crop. Usually winter hardy in USDA zones 4 and warmer, resuming growth the following spring. While top growth may be slow in the winter, it acts as a blanket to your soil, preventing erosion from wind or water and the deep roots are still growing, feeding soil organisms, and improving soil structure and water retention. Fairly drought tolerant and also tolerant of temporary flooding.