Kae Verens said:

I keep seeing references to zones.

What are they?

A method of catagorizing the severity of winter weather, in terms of minimum
temperature only.

I'm in Ireland, for example, what zone would that correspond to? I never see any
mention of this in any books I've bought.

Zone 8 (with some zone 9 on the coasts).

Zone 8 (15 F) (-9 C)
Zone 9 (25 F) (-4 C)

You should be able to grow camellias...

See:

http://www2.dicom.se/fuchsias/eurozoner.html
--
Pat in Plymouth MI ('someplace.net' is comcast)

Any technology distinguishable from magic is insufficiently advanced.
(attributed to Don Marti)