Every year about this time I check the long-range winter forecast for the Pacific Northwest.

Most professional prognosticators are predicting a "normal" winter for temperature but an above-"normal" winter for precipitation. But I don't know what "normal" is for our part of Washington.

I've lived here since 1980 and I've experienced winters that vary from cold and snowy to mild and dreary to very cold and dry. It certainly keeps me from becoming complacent.

Recent winter temperatures have been mild and have allowed plants not designated as winter hardy for our area to grow successfully. Some gardeners like to live dangerously. If we have a normal winter, damage or even death may occur to these plants.

What is considered normal for our region can be discerned from the plant hardiness maps. The first official USDA Plant Hardiness Zone map was published in 1960. The zone map showed 10 zones across the U.S. based on the lowest annual minimum temperature. Zones were based on 10-degree gradients. On that map our region was located in Zone 6 (-10 to 0 degrees). Woody landscape plants were rated by their hardiness to indicate in which zones they could be planted and expected to survive the winter. Before that, gardeners just had to guess, depend on word of mouth, or consult other gardening references.

In 1990, the USDA divided the zones into "a" and "b," with "b" being the warmer part of the zone. Our region was located in Zone 6b (0 to -5 degrees) and our warmest areas in Zone 7a (5 to 0 degrees).

The American Horticulture Society was asked to draft a new map for the USDA in 2003. It went back to 10-degree gradients. The 2003 draft version showed our region in Zone 7, 10 to 0 degrees. The USDA rejected the much-criticized 2003 draft and decided to work on the map internally, but is still publishing only the1990 version.

In 2004, the Arbor Day Foundation used the same extensive recent climate data and published its own Arbor Day Hardiness Zone map. It is similar to the 2003 AHS draft version. On the Arbor Day map we also are in Zone 7 (10 to 0 degrees).

Confusing? What it all means to me is that I can feel fairly safe planting trees and shrubs designated as Zone 6 or Zone 7. You won't find me gambling on a Zone 8 plant.

Who knows what this winter will bring? Just in case we have a cold winter, here are some ways to protect your plants.

1. Mulch marginally hardy plants in mid-November after the soil cools.

2. Hardy plants in containers should be moved into the garage or a sheltered place where their roots won't freeze. Leaving them outside and insulating the container or pot won't work since they aren't a heat-generating organism like an animal.

3. Dig tender (gladiola, begonia, dahlia, canna) bulbs, corms and tubers and store them as recommended over the winter where they will be protected from freezing temperatures. Gambling gardeners sometimes leave these in the ground and mulch them heavily.

4. Don't forget to water your plants as we go into cold weather. It's especially important that shallow-rooted plants (arborvitae, birch, spruce, rhododendrons) and evergreens not be allowed to go dry during the mild fall and winter months. Even if plants are dormant, they can suffer drought stress and damage.

Learn more about the Arbor Day map and see how the zones have changed from 1990 to 2004 at www.arborday.org/media/zones.cfm.

* Marianne C. Ophardt is a horticulturist for the Washington State University Extension Office in Benton County.