Postharvest Recommendations for Small Horticultural Farms
Recommendations for vegetables for small gardens can be found at https://extension.umn.edu/planting-and-growing-guides/harvesting-and-sto....
Extensive postharvest recommendations for individual fruits, vegetables, and ornamental crops (geared primarily for wholesale operations) can be found in USDA Handbook 66 -
More postharvest information, including sources of equipment and supplies, recommendations for handling individual fruits and vegetables, information specific for small operations, information in languages other than English, can be found at the University of California - Davis Postharvest Technology website.
Postharvest recommendation for organic operations can be found here.
Information on building root cellars are available from the University of Alaska. Root cellar temperatures often do not get below 40F, and can fluctuate over time.
Information on building walk-in coolers were provided by Jim Thompson of the University of California - Davis. Build a walk-in cooler if you can afford it and are planning to sell wholesale, such that you need better temperature control than what a root cellar can provide. You can build one in a garage:
Use a CoolBot to control the temperature.
If you have more than one cooler, you can learn what commodities can be stored together here.