Question from an onion novice.

[HopeHoops]

4. The seeds are cheap. Plant every month, harvest what grows. Same with radishes and lettuce.

The latter two put out extensive root systems even if the produce isn't edible because of weather. That builds the soil. Onions are just good. They grow easily from seed and sets, but seed is cheaper. You can also sow them in the late summer and over-winter them for spring harvest.