Seeds left over from planting the spring garden may be used in planting the fall garden if the seed is stored in a cool, dry location or in a refrigerator or freezer.

Seeds that are stored in the freezer properly should remain viable for many years. Immediately following planting, return surplus seed to the freezer.

In order to get early established growth, supplemental irrigation is desirable. Most vegetable crops will benefit from supplemental irrigation. Information on drip irrigation may be available from garden centers and county Extension centers.

https://extension.okstate.edu/fact-sheets/fall-gardening.html