Zones temperature and hardiness:

USDA zones are based on 30 year temperature records kept at official weather reporting stations. Of course the weather can vary widely between those reporting stations so it is important to pay attention to weather in your own garden. Most importantly it is best to know that our climate is similar to others but when it comes right down to it , it is our own. Therefore, we don’t like to classify it as anything other than what it is. If you live in western Washington, its western Washington’s climate. In  western Oregon, guess what? You got it.

We have a winter wet, summer dry climate. Winters are cool and wet, the amount of time we spend between 35º and 55ºF- IT CAN BE MONTHS! Spring, quite often is showery and cool and summer is dry and pleasant, intermittently hot, before fall which is quite often showery and wet. Arctic air can intrude and last for a day or up to 10 days. It is usually gone pretty quickly and gives us our coldest weather in quick dramatic shots. Cold hardiness, the adaptation of plants to take cold has many determining factors. It is important to meet a plants ultimate cultural requirements for it to achieve its full hardiness to cold. Even when those requirements are met- topsy turvy weather can cause even more havoc. Take into account a plants adaptation to soils, moisture, siting and we think its best to look at each plant on a case by case basis.

In western Oregon and Washington our winters fall into these zones.

Zn10a  35º to 30ºF

Zn9b   30º  to 25ºF

Zn9a    25º to 20ºF

Zn8b    20º to 15ºF

Zn8a    15º to 10ºF

Zn7b    10º to  5ºF

Zn7a      5º to  0ºF

Zn6b      0º to -5ºF

Zn6a   -5º to -10ºF

Zn5b  -10º to -15ºF

Zn5a   -15º to -20ºF

Zn4b   -20º to -25ºF

Planting based on zones

We list the specific zone for plants not just a as a guide to over all cold hardiness but as a guide that also tells you when it is best to plant. We like to follow this rule:  If a plant is hardy to zone 7 (below 10ºF) or lower it may be planted in any season of the year. If it is designated as zone 8 (10º) or above it is most safely planted in the spring before June 15th. This allows the plant to become well established before its first winter in the ground. Take special care to water spring and summer plantings regularly through the dry summer.

Climate Zones

Temperature and patterns of precipitation have a profound influence on our gardens. It allows us in the PNW to grow an extraordinary range of plants. The more you know about the climate a larger diversity of plants will succeed in your garden

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Plants for problem areas