As the soil warms and daylight extends a bit longer each day, Oregonians start planning their gardens.
But did you know the U.S. Department of Agriculture updated its plant hardiness zones a few months back?
This spring, The Oregonian/OregonLive has created a plant zone lookup tool that accounts for the USDA’s recent update of the zones. Readers can simply type in their address to find their zone and toggle to check whether it changed from the prior USDA map, last updated a decade ago.
The zones identify average extreme minimum temperatures and help gardeners determine which perennial plants are most likely to thrive, according to the USDA.
How many people will see changes? Nationally, zones in half the country saw changes.
In Oregon, The Oregonian/OregonLive data specialist Mark Friesen analyzed the new map. He found that nearly 60% of Oregon land stayed in the same zone. (For Portland and much of the valley, that is zone 8b, where minimum temperatures reach 15 to 20 degrees.)
But 38.6% of Oregon land shifted warmer, to the next half-zone, and about 1% moved a full zone warmer. Just 2.5% moved to a cooler zone.
Here’s the tool, updated with new USDA zones:
Nationally, The Conversation reports: “Comparing the 2023 map to the previous version from 2012 clearly shows that as climate change warms the Earth, plant hardiness zones are shifting northward. On average, the coldest days of winter in our current climate, based on temperature records from 1991 through 2020, are 5 degrees Fahrenheit (2.8 Celsius) warmer than they were between 1976 and 2005.”