At Frog Song in Alachua County, FL, we grow a spring onion crop of Yellow Granex variety, which is the same for Vidalia onions.
We sell our fresh onions during March and April. Once the tops “drop” in May we harvest our remaining crop to cure at our organic farm for sale during the summer.
We place all onions on flat racks that stack in our curing room, a modified shipping container with many fans including large exhaust fans.). The warmth from the container walls and constant air circulation helps dry the onion skins down while the flesh converts chlorophyll to stored sugars. We rotate the racks to try and keep everything drying evenly.
The result is a dried storage onion that will last up to another 2 months from harvest and has a much sweeter flavor than the green onions we started with.