I'm in Albuquerque which I'm told is zone 7, and looking in a few
books they too show zone 7 (large US maps). However I snagged a
copy of Sunsets "Western Garden Book" from the local library
Saturday and it shows me in zone 10 (state map and of course more
detailed than a US map). Could this be an error? 3 zones is an
awfully big discrepancy. It doesn't show a 7 in the entire state!

Before you ask, No, I've not contacted a nursery - YET - since
reading this as I just ran across it an hour ago.

They're two different zone descriptors -- i.e., different systems. Paul
James did a great segment on this on his Gardening By The Yard show on HGTV.
Here's the article from HGTV's website:

Twilight Zones
Gardening by the Yard : Episode GBY-713
http://www.hgtv.com/hgtv/gl_seasonal...1_1399487,00.h
tml

The Virginia sweetspire 'Henry's Garnet' (Itea virginica) is recommended for
Zones 5 to 9. That means it won't survive the winter north of Zone 5, and it
will stand up to the summer heat in Zone 9.

When it comes to gardening zones, there are no absolutely hard and fast
rules.

Most gardeners are familiar with the U.S. Department of Agriculture's Plant
Hardiness Zones, which were established several decades ago and revised in
the early 1990s. The zones, which number 1 to 11, give gardeners an
indication of whether a given plant will survive the winter in their area.
Zones are included on most plant tags and in catalog descriptions and
reference books.

Master gardener Paul James lives and gardens in Zone 6, where the average
annual minimum temperature ranges from 0 to -10 degrees F. So if he tried to
raise a plant that's rated for the southern limits of Zone 7, he'd have to
give it extra protection in the winter, such as a thick layer of mulch or
maybe wrapping the whole plant in burlap. Even then, the plant may not
survive. On the other hand, a plant rated for Zone 8 would have to be
treated as an annual in James' garden because it wouldn't survive the
winter. Plants rated for Zones 3, 4 and 5 will probably do fine there, if
they can tolerate the hot, humid summers.

To address concerns about summer hardiness, the American Horticulture
Society developed a heat zone system that divides the country into 12 zones,
based on the average number of days with temperatures above 86 degrees F.
According to this system, James gardens in Zone 8, an area that has 90 to
120 days of temperatures warmer than 86.

By combining the results of the USDA Plant Hardiness Zones with the AHS heat
zone information, you get a more exact understanding of which plants will do
well in your garden--both in winter and summer.

The highly respected Sunset Publishing Corporation developed yet another
system that divides the country into 45 different zones. This system pays
particular attention to microclimates across the country, especially where
climatic changes can be abrupt, such as mountain regions, coastal areas and
deserts.

As if all that weren't enough, the National Arbor Day Foundation has a zonal
map specifically for trees.

Is all this zonal information really useful? Absolutely. At the same time,
though, all these systems can be mind-boggling. What's the solution?

"Unfortunately, the only real answer for serious gardeners is to bone up on
all the zonal information that's out there," James recommends. "For casual
gardeners, rely on local information such as plant retailers (who, after
all, wouldn't be in business long if they sold plants that weren't adapted
to your area), master gardener organizations and fellow gardeners.

"But having said that," James continues. "I think that serious and casual
gardeners alike spend far too much time fretting over zones, especially USDA
zones. After all, before the USDA map was revised in the early 1990s, I was
in Zone 7; now I'm in Zone 6. But all the plants that were rated for Zone 7
are doing just fine, and I haven't given them any additional protection."
Plus, says James, millions of people live in areas that straddle two or more
zones. "If they limit their plant selections only to those rated for their
exact zone, they would miss out on some great plant possibilities."

Why this distinction between serious and casual gardeners? "There are all
kinds of gardeners out there, from the weekend warrior whose primary goal is
to have the best-looking lawn on the block to the horticultural hardcores
who spend countless hours tending their ever-expanding palette of rare and
unusual plants," James says. "The needs of each differ greatly, especially
in terms of the plants they choose. I'd encourage casual gardeners to stick
with plants that are rated for their specific area, if not their actual
zone. But I'd encourage serious gardeners to branch out a bit, because they
may be more willing to create microclimates so that they can grow plants
that are rated one or maybe even two USDA zones south of their own, and
they're likely to be more willing to provide plants extra winter protection
and extra TLC in the summer."

Thankfully, however, the bulk of plants out there appeal to both serious and
casual gardeners, says James. "The vast majority of them don't need a lot of
maintenance."