Harvest cereal grains about 7 to 10 days before they’re fully mature and dry. The grain heads should still be greenish or just turning yellow, the stalks mottled with green. Pinch a kernel with your thumb and index finger. It should be soft enough to be dented by your thumbnail, but not so soft that it squashes.
Cut the stalks just above ground, and gather and tie them into bunches. (The traditional tool for cutting grains is a scythe.) Stack or hang the bunches in the field or under cover to dry. The grain will cure in 10 to 14 days. When you bite a kernel between your teeth, it should be hard and crunchy.
To thresh, put a bundle or two on a sheet spread over a hard surface, such as a patio or floor. Beat the seed heads with a length of rubber hose or an old mop handle to knock the seeds from the stalks.
Next, clean the grain of chaff and hulls. Pour the grain slowly from one bucket to another in front of a fan. The breeze should be strong enough to blow the chaff away, but not to take the kernels with it. Repeat until clean.
Keep small quantities of cereal grains in a refrigerator or freezer. You can also store thoroughly dry grain in a cool, dark place in sealed jars to protect it from insects.
Hulling grain with tough hulls is one of the biggest stumbling blocks for home gardeners. You can hull small quantities by roasting the grain in an oven at 180°F for 60 to 90 minutes, and then running the kernels lightly though a blender and picking out the cracked hulls. For larger quantities, use a grain grinder.
Grains can be cracked or ground into flour in a good household blender. Grind ¼ cup at a time, taking care not to let the motor labor too much. If you make a lot of flour, you may want to buy a hand-cranked or electric flour mill. Grind only as much as you will use in a few weeks, and store prepared grains in the refrigerator or freezer; they go rancid rapidly.