This person wrote this info on them. I will add what I find below the post.
A HERITAGE VARIETY ONION SETS, MULTIPLIER ONION SETS. These are the kind your Grandparents had that makes green onions in fall and winter. Save bulbs for next year. I paid $5.50 per pound, shipping $6.25
The paper included said. Plant them all. Large or small, all will produce green onions, or leave them to make bulbs, each cluster in this box is from 1 small set.
onions do best if the soil pH is between 5.5 and 6.5, a little on the acid side.
Add organic matter, like compost or dry leaves decayed leaves .it acts like a sponge, holding moisture near the surface. That's good for onions, which have shallow roots and can't tap water or nutrients deep in the soil.Clay soil will puddle water on top. So sand and humus/manure should be added.
I am planting in a raised bed. With lots of humus/manure. I have read, Onions like to feed 2x as much as other vegetables. If you find your onions have pale yellow or greenish yellow leaves, that would indicate that onions could lack nitrogen. Also leaves can yellow after long, wet periods of weather because a lot of rain washes nitrogen from the soil. It's difficult to over-fertilize onions. They require quite a lot of nutrients.