Once only thought beneficial for farms and market gardens, they are now being grown in all kinds of gardens.
Gardeners use the term cover crop and green manure in similar ways.
There are some differences but the main thing is that you are building the organic content of your soil and reducing your dependence for chemical use on your land. September is a good time to plant over wintering cover crops. If your winters are mild and you garden in Zones 8 or south, you will be able to plant and till under a sowing of a green manure crop before planting your winter cover crop. Make sure to sow the seeds of your winter cover crop at least 30 days before the last frost date in your area. Cover crops add large amounts of organic matter to your soil and provide many other benefits to your garden area.