Climate Zone – What the heck is that?

I had an interesting question from my friend Angie last week:  “What the heck is up with the zone stuff.  And if something says hardy to zone 3 what does that mean???”  So, here you go Ang! First, a picture of part of our San Francisco Bay Area reason, just thought you’d like it:)

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Climate zones are a way of mapping out typical weather for different areas. Our climate zone here in Santa Rosa is zone 14, according to the Sunset Magazine Zone chart.

What does that mean?

Well, we have moderate temperatures (except for our few freaky scorcher days) which includes warm summer days but usually cool evenings. Our summer months typically include foggy mornings, which burn off to sun midday.This can be more or less pronounced depending on where you live….Rohnert Park, for the 15 years I lived there, had far worse fog than Santa Rosa because of where they are situated in relation to the gap in the mountain range that allows the fog to roll in from the coast.  Sonoma has much less fog and higher temperatures because they’re beyond yet another mountain range that blocks out more of the fog, but it’s generally the same kind of weather and each town is in zone 14. Each climate zone is known by it’s high and low temp, frost dates, etc. (We often tend more toward Zone 15, but hey, I didn’t write the map:))

Why should I care?

Lets say you want to plant green beans. You need to know your zone so you’ll know the last frost date and therefore the first safe date to plant frost sensitive plants.  Here that “safe” date is April 15. (However, green beans need a higher soil temperature to sprout without rotting so I know to wait a couple of weeks past that date to let the soil warm up). .Also, the Sunset Western Garden Book, the go-to garden book, always tells you which zone is ideal for which plant. So, if a plant label or garden book article says, “hardy to zone 3…” that means it will not do well in temperatures colder than zone 3…it will freeze!.

How does it affect the plants I pick?

I love hydrangeas. I can’t live without them! But, they are picky little ladies. Now, if I lived in Mendocino,( cool and foggy a LOT- zone 15) I could practically  plant them in full sun.  It doesn’t get hot and they don’t burn.  They are very sensitive to hot sun and do well there.  But, in my yard, knowing my zone isn’t necessarily ideal for them, I have gone to great lengths to put them in semi shady spots, even building a special shade cover for some of them. All because I know summer weather in our zone can wipe them out in one day!


Or, say you want to grow an orange tree here.  We don’t have the heat they need according to our zone. What to do? You could plant them on a south facing wall. That is an example of a “micro-climate”. A zone within a zone so to speak.  It will be hotter there and they will do better than they would a few yards away.  A stucco wall with raise the temperature even more.  It’s all about checking out the micro-climates in your yard and using them to your advantage.

Where do I find my “Zone” (And a bunch of other great information)?

Right here:

While zone maps aren’t absolutely accurate for every garden, they are a great guide and get you thinking about the climate you live in and the micro-climates you either have, or can create, in your own garden!





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