In Search of Microclimates
Have you ever wondered why your plants do poorly while your neighbor’s plants absolutely thrive, even if you planted the same things? It is probably due to differing microclimates. If your house faces north, your growing area gets a lot less sun, less heat and less growing time. Shade, sun, slopes, humidity, prevailing wind, and more contribute to what creates a microclimate.
A microclimate is an area with unique weather conditions that differ from the surrounding area. These weather effects can vary from a few square yards to square miles. Some things that create a microclimate are simple, like sun and shade. All you need to do is observe over a few days or, occasionally, a few seasons. Other things like temperature can be trickier.
I have two great tools to help me find those secret microclimates. The first is my dog, Tucker. Where he decides to take a nap is always warmer in the winter and cooler in the summer. Add in your own sun/shade observations and you may have discovered a new prime growing spot. (You will need to add some portable fencing to help him decide to find a new spot to nap, though.)
My other tool is a home weather station (I have two). One is placed outside on the roof, and one, that’s temperature only, I move from place to place. By comparing temperatures, I can find places that don’t freeze quickly in the winter and stay cooler in the summer while still getting enough sun. My weather app shows other connected weather stations in my area and, by comparing those readings to mine, I have discovered that the cul-de-sac where I live, surrounded by hills on three sides, is a small microclimate all by itself. I average five degrees cooler in summer and five degrees colder in winter. My apple trees, which require cold hours, love it, but my peach tree often loses fruit to frost. Me, I will take the cooler summer anytime.
Small microclimates are something you can create. Think “greenhouses.” I have low tunnels built over some raised beds, adding two to three degrees in the winter and added humidity. This allows me to grow some cold hardy crops like butter lettuce, bok choy, cabbage and broccoli all winter long, even when it snows. Raised beds are another way to change growing temperature. Ground temperature is cooler in summer and winter except in my low tunnels, where the ground temp is higher in the winter because daytime temps in the tunnel are significantly warmer. That allows earlier seed starting, as well. In another smaller low tunnel next to the south wall of the house we added a thermostat and a single set of incandescent Christmas lights. Set to come on at 38 degrees, it keeps my wife’s bird of paradise, bromeliads and various geraniums frost free all winter.
If my dog can use microclimates, I can, as well. With a little effort, I can even move my growing zone into the frost-free zone, in a tiny space, to remind me of Maui.
Jim Bliss is a University of California Cooperative Extension Master Gardener of Tuolumne County.
