I don't know if I'd use the Arbor Day Foundation zip look-up. I mean, that isn't "official" and just because they are claiming to use more current information than the USDA (which is stuck in 1991 - just to be PC) doesn't make ADF all that trustworthy. IMHO
Click on your state and then pull out the magnifying glass. It also helps to have really good color vision . . . You can also look at the chart for "Average Annual Minimum Temperature."
Your memory may serve you as well as anything there: What was the coldest temperature last winter & what has been the coldest temperature since you moved to your current home? What is the coldest temperature the little old lady down the street (who moved to the neighborhood in the 1950's) remembers?
The idea is that you won't be setting out an avocado tree or something that can't survive a winter night with that much cold.
Putting in your zip code will give you both the USDA and Plant Maps designation. I suppose it is a little easier than pulling out the magnifying glass for the USDA website. Still . . . and this is a little bit of a gripe for me . . . Oregon State University (I believe it was) received a pile of federal money to rework the USDA Hardiness Zone map using more current temperature data.
Dead in the water!! Or, I should say "dead in the political water."
Steve, according to my eyesight and colors, I'm in zone 11? That doesn't seem right. Nifty is in 8b and I'm about 30 min. from him. I just realize that my profile doesn't show my zone, I just put in San Francisco bay area. I need to probably update/change this.
Am I in zone 8b?