In article , Rodger Whitlock
writes

Now, now, Nick, temper, temper. The USDA zones were devised with
a specific purpose in mind, hardiness of *woody* material in the
continental USA.

Eggsacly - you hit it in one.
And as this is a newsgroup for discussing gardening topics relevant to
the UK, USDA zones, being pretty well nigh useless in the UK, are not
really on topic!!

--
Jane Ransom in Lancaster.
I won't respond to private emails that are on topic for urg
but if you need to email me for any other reason,
put jandg dot demon dot co dot uk where you see deadspam.com