In article , Eur Ing John Rye
writes
I would agree with that my typical ones are 5-6 inches in diameter. They do
need adequate water, and I remove the bottom leaves as they split. I suspect
the commercial growers are using a different variety to us amateurs. This
year I tried to compare Monarch, and Balder, but the birds pinched the
labels, so it is try again next year.

Just a guess here - are celeriac much grown commercially in UK, or are
they more often produced in milder places like the Canary Is., Israel
etc. in a similar way to other half-hardy and tender crops?
--
Alan & Joan Gould - North Lincs.