The "zone" you see referred to here and elsewhere concerning plants are "plant hardiness zones".

The link at the bottom is to a Plant hardiness zone map of New Zealand and an explanation of why knowing what your zone is, is so important.

Here is a link that might be useful: New Zealand plant hardiness zone map

Here's a link to the US National Arboretum plant hardiness zone map if anyoneÂs interested.

Here is a link that might be useful: US National Arboretum plant hardiness zone map

Bev,

The Zones can be a little misleading, but not dramatically so. The most relevent info about them is the average minimum winter temps.

Kiwiland is definitely a bit more "tropical" than the UK as evidenced by the species that grow naturally but they are rated the same.

Altitude is important as well. Half up Mt. Cook is probably Zone 6 in the middle of Zone 9.