Zoomable California Cold Hardiness Zone Map

[Scott]

This is probably not new for most here, but at last I seem to have found a map that shows my specific area as I'm wedged between two hills in a mountainous area. It places me between a 9a and a 9b. Maybe it'd be of help to others to in hard to pin down areas.

http://www.plantmaps.com/interactive-california-plant-maps-zone-hardiness-map.php

[Scott]

Actually this is a USDA map and funny enough it places me between 3 variations of the same color which are not explained on the legend on the left. hmmmm

http://www.plantmaps.com/interactive-california-usda-plant-zone-hardiness-map.php

Edited April 5, 2014 by Scott

[DALION]

I like the map but think they are generous with the ratings. I think that my area is a 9b and can be considered 10a in a good year but this site says 10a or 10b on the two maps.

[Mauna Kea Cloudforest]

I like the map but think they are generous with the ratings. I think that my area is a 9b and can be considered 10a in a good year but this site says 10a or 10b on the two maps.

That map looks like total garbage to me. It's got Santa Cruz as USDA 9a, yet the USDA has a lot of the same areas as 10a and 10b. It also has Riverside as 8b and 9a, but there are foxtails and Cuban Royals around here, which I know don't grow in 9a. This map is total junk.

Take a look at this map, this is the correct one run by the USDA, you can zoom in nicely and you will get a much more accurate picture: http://planthardiness.ars.usda.gov/PHZMWeb/InteractiveMap.aspx

[Scott]

That is a good map. Funny it actually cut's my street in half between a 9b and a 10a! I knew that there are some serious micro-climates here. Thanks for sharing that. I also appreciate the color accurate legend.

[Jubaea]

It does not seem to be very accurate having 9b in areas I know to be zone 10. The best thing to do would be to get some max/min thermometers and place them around your yard. Having 2 calibrated to the same temperature will allow you to find the best microclimate in your yard. This will also allow for comparisons to official stations record to determine if you are warmer or cooler than them.

[ghar41]

Listing my area at 9a may be more more accurate than other USDA maps that list my area as 9b.

However, California's climate is much too complex to be divided into 5 or 6 growing zones (outside of the Sierra Nevadas) as is done by the USDA maps. Listing both San Francisco and Whittier at 10a misses the point entirely.

The Sunset Guide zones have always been more useful to me. San Francisco's zone 17 is unique to Whittiers zone 23 in some important ways that are valuable to palm growers.