Observe your own microclimates

General Discussions
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I’ve been keeping an eye out for biomarkers of what microclimates are doing what things in my yard. The presence or absence of frost / snow can be useful because it’s so obvious. The presence or absence of particular species of weeds, while more subtle, can be useful, too.

I’m in the northern hemisphere, so in winter, the south side of my yard is supposed to be warmer, and the north side is supposed to be colder. Is that true in my yard?

Nope. Not in the least.

The south side of my yard, which is in full shade in winter (due to my neighbor’s house) has been covered in frost for two months. It hasn’t melted at all, even during weeks of 60 degree daytime temperatures and 40 degree nighttime temperatures. The south side must be staying about 30 degrees colder than the middle of my yard. That means if I want to put any perennials there, I need to assume that the south is three entire growing zones colder than the reported temperatures for my city. (!!!)

Meanwhile, the north side of my yard, which is in full sun all year-round, still has bindweed with green leaves. The leaves are starting to look a bit yellowish at the tips, and the bindweed’s growth has stalled, so it’s clearly right at the edge of its cold tolerance.

Bindweed is reported to be hardy to 21 degrees Fahrenheit. (Sadly, this only includes the tops. The roots are fiiiiiiiiiiiiiiiiine when things get much colder up top.)

My city had reported nighttime temperatures of 14 degrees Fahrenheit for several days in a row, a few weeks ago.

This implies that the north side of my yard consistently stays about 5 degrees warmer than the reported coldest nighttime temperatures of my city. This tracks with what I’ve noticed in terms of snow, too – snow always melts there first, and the ground is almost never frozen solid there.

Guess where I should put my shade tolerant, hardy-all-the-way-to-zone-4 perennials?

Guess where I should put my evergreen, sun-loving, just-barely-hardy-to-zone-7 (that’s my zone) perennials?

Not in the places common wisdom would suggest!

Keep an eye out for the microclimates in your growing space. Some things may surprise you.

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Good reminder! Definitely something I wish I had paid more attention to over the years. I have a general idea that the east side of the house is a lot cooler and more shaded than the west side which gets completely cooked.

But there are plenty of other areas I have not given as much thought to (behind the garage? Or between the garage and a row of fence to the south? Around the pump house? Temperature differential between woods and yard? I know it’s pretty big in the heat of summer, but what about winter?).

Given the time, energy, and money, I would be sorely tempted to build out a cool little network of sensors to measure temperature and humidity, possibly other stuff like air “quality”, and rainfall/precipitation measurement if that can be done easily (I am aware of very simple and pretty inexpensive sensors for the other stuff, not sure about this, but it seems like it should be doable?)… hmmm…

Ooh, I guess a light sensor could help measure how much sunlight that spot was getting.

And maybe a soil probe sensor would allow for measuring moisture in the soil…

I feel like building a little network of those to place around the property and send their readings back (or record them on an SD card if they are out of wifi range) and then have the ability to graph the readings out and/or compare them to readings from other sensor locations on the property would be really cool and potentially quite valuable.

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Speaking as someone who loves data, that sounds like a really interesting project.