Know Your Zone, Know Your Microclimates

Hardiness Zones

Knowing the hardiness zone you live in will be the difference between whether your plants come back next spring or not…unless they are annuals, of course.

I’ll never forget the time I was walking through a local Home Depot garden area, when I saw a customer ask one of the workers if the the gorgeous Bougainvillea she was eye-balling would be OK to plant here….and he said yes. Neither one of them bothered to look at the plant’s information tag to see if it was hardy in our area. The $50 price tag on this beauty was nothing to sneeze at, so I meandered over and mentioned that it wouldn’t survive the winters here. Both looked at me with blank stares. I mean, if the local Home Depot was selling it, surely it’s a good plant for our area, right? Wrong. Most any plant will live throughout a spring/summer/fall growing season, no matter where it is located, but the real kicker is the winter. So, if you just have to have a Bougainvillea, know that you’ll be treating it as an annual if you live in the Denver area. Take lots of pictures because come next spring, you won’t be seeing it again … unless you put it in a large pot and you’re lucky enough to have a greenhouse to overwinter it. Too dang much trouble in my opinion.

Sunset.com has a great hardiness zone map that will tell you both heat AND cold hardiness zones, rainfall, humidity, etc. All these factor in.

Typically, it’s easy enough to see what cold hardiness zone you are in based on the information below:

Zone 1: below -46 C (below -50 F)
Zone 2: -46 to -40 C (-50 to -40 F)
Zone 3: -40 to -34 C (-40 to -30 F)
Zone 4: -34 to -29 C (-30 to -20 F)
Zone 5: -29 to -23 C (-20 to -10 F) << this is me!
Zone 6: -23 to -18 C (-10 to 0 F)
Zone 7: -18 to -12 C (0 to 10 F)
Zone 8: -12 to -7 C (10 to 20 F)
Zone 9: -7 to -1 C (20 to 30 F)
Zone 10: -1 to 4 C (30 to 40 F)
Zone 11: above 4 C (above 40 F)

Microclimates

Knowing where your microclimates are is the same as knowing where the secret spots are in your garden to plant something that wouldn’t normally thrive in your zone. You don’t need to be a trained horticulturist to know where these are at. Just pay attention to where the cold seems to hang on longer or the spots that always seem to be hotter than most others. These are your microclimates. A warm microclimate would allow you to plant something a zone (maybe even two?) above your hardiness zone.

What does that mean?

If you have zone envy for a plant that says it is hardy to zone 6 and you are zone 5, you should be able to plant it with success if you put in a warm microclimate. Each and every home is different and will depend on the shade of a tree, a neighbor’s house, the direction the house sits on the property, the location of the nearest heat reflective surface (house, concrete, bricks, blocks, rocks, etc.) South and West facing locations will be the most common places to look for warm microclimates.

All that said, don’t forget to take into consideration the other important factors that will allow your plants to thrive: soil, water, sun. All of this information is located on the information tag that you’ll see in the plant’s container. PLEASE pay attention to these. If you don’t know what type of soil you have at your location, how can you possibly know if the plant you’re buying will be happy there? Or if you’ll need to amend the soil before planting?