The Q&A Archives: Climate Zone Change In Portland, Or

Question: I've heard that the USDA Zone for Portland, Or is being changed from 8 to 9. What can you tell me about this change.

Is there a similar change in the works for the Sunset Western Garden zone from 6 to ???

I'm in the beginning stages of re-doing my yard. Any info will be greatly appreciated.

Answer: The Plant Hardiness Zone Map is of great importance to all gardeners to help them make the correct plant material choices for their zones. Sunset Western Garden Book goes one step further by dividing USDA zones into smaller microclimates. These additional zones reflect elevation and proximity to bodies of water, both of which can make a garden warmer or colder than gardens only a few miles away.

A new USDA zone map is in the making. The map is based on temperature information collected between the winter of 1986 and March 2002, which corresponded to a period of warming temperatures in many areas of the United States. As a result, many areas have experienced zone creep, with zones edging northward slightly.

Even if the new map indicates your zone has changed, experts advise against making radical changes in your plant choices. The draft map is currently under review by the USDA?s Agricultural Research Service (ARS). Eventually the map is expected to be available on the ARS Web site (

Hope this information is helpful!

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