https://www.gardeningknowhow.com/edible/vegetables/onion/onion-bulb-formation.htm
Many onion varieties are relatively easy to grow. That said, onions do have their fare share of issues with bulb formation; either the onions do not form...
onion bulbsgetonionsform
https://www.rhs.org.uk/plants/221494/allium-fistulosum-summer-isle/details
Find help & information on Allium fistulosum 'Summer Isle' onion (salad) 'Summer Isle' Bulbs from the RHS
allium fistulosumonion saladsummerislebulbs