What Growing Zone Am I In?

What are frosts and freezes? And do they apply to SoCal??

I personally, am in growing zone 10a in southern California. This means…. we don’t really have a true freeze here, but we do have a “frost date”. We also have very…. very hot summers. We do luckily have a lot of growing time.

A zone is one number, and it means one thing…

Your zone is the average coldest night of your winter. That's the whole measurement.

The USDA looked at thirty years of weather and asked one question of every spot on the map: how cold does it get on the coldest night of a normal year? Then they sorted the country into bands.

To put it simply, your zone tells you whether a plant will survive your winter!

It knows nothing about your summer, your soil, your wind, or the microclimate of your own yard. So thats’s why it’s so important to really start paying attention to where you get sun throughout the year, where your trees give shade, where you get wind, etc.

Look your zone up!

Your zone: planthardiness.ars.usda.gov — type in your zip.

Your frost dates: garden.org's frost tool or the Old Farmer's Almanac.

If two websites give you two different zones, that's normal. It's the first clue that these lines are blurrier than they look! Where I live, sometimes I see I live in zone 10a and sometimes 9b. However, I tend to relate more to the gardening specifics of 10a.

So, what would a frost be in 10a?

A frost is a night cold enough — around 32 degrees — that the water inside a plant's cells freezes and bursts them. That's the blackened, sad-lettuce look you find the next morning. It isn't the cold that kills. It's the ice!!

We do get them here in 10a. When I look up my zip code, it tells me my frost risk starts around November 6, and by mid-DecemberI've almost certainly had one.

It also tells me my last frost is somewhere around mid-April, which has not been my experience at all. Some years I'm planting tomatoes in March and everything is fine. Also some years November and December are still very hot.

And that's the most useful thing I can tell you about all of this: these are averages, not promises. Your garden and the ever changing weather/climate gets the final say.

What helped me most

What has made a better gardener so far has been talking to people who garden within about ten miles of me and following a bunch of gardeners online who garden in zones 10a and 9b. Reading books and articles from my zone and a lot of trial and error.

Happy Gardening, friends!