The message
from "Geoff" contains these words:

OK, call 'em bunching onions if you like that awful name!

This morning whilst in a garden centre I got into conversation with somebody
who was buying some onion sets. He said that he'd given up planting seed
and now uses onion sets which produce spring onions in three to five weeks.
He said that he'd tried Japanese onions but considered them yuk and advised
me to buy Stuttgarter sets. He said he plants them 2 inches apart in a
largish tray (one about inches deep) of multipurpose compost. He grows
them by the window of his garden shed

I think you're confused about different sorts of onions.

Spring onions, syboes in Scotland, are a mild and tubular green at one
end and white at the other.They can only be grown from seed. However
long you grow them for, they will never become big round "dry" onions as
sold in supermarkets.

Onions like Stuttgarter, can be grown from either seed or sets. Both
grow into the big round dry onions sold in supermarkets. They won't grow
into syboes. Early green shoots of seeds or sets could, I suppose, be
cut and eaten, but they are hollow and a different flavour from syboes.

If you want some quick, oniony-tasting greenery for garnishes, chives
are fast, and the cut plants will regrow repeatedly.

Janet.