According to the online Garden Helper's Dictionary, a micro-climate (microclimate) can be thought of as "variations of the climate within a given area, usually influenced by hills, hollows, structures or proximity to bodies of water."
So what does this mean, and how can it affect gardening and landscaping projects around your home?
It could mean that it's a lot colder (or warmer) where you live, compared with the next town, the next street . . . or even just 10 feet away from your chosen planting spot.
Gardeners should greet this as wonderful news. Once you begin to understand some of the intricacies of micro-climates, it will allow you to get away with 'daring' experiments with plants that normally would not survive in our climate.
*And yes, although the 2021 “Snowpocalypse” and even this winter are trying to put that micro-climate “warmer” zone anomaly to the test, it can still be achieved with strategic placement and planning (light colored west facing walls, protected niches and similar).*
To help understand and capitalize on this fascinating subject, here are six micro-climate concepts.
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1. Urban Heat Islands: Buildings, roads and other concrete structures within cities absorb heat all day; they then release this warmth slowly at night and raise the average night temperatures compared to the surrounding outer edges of the city. Notice how Camp Mabry’s low temps are always several degrees warmer than readings from the airport east of town. When I lived in Round Rock, right by Dell, I could get away with more tropical and semi-tropical plants at my house than my mom who lives south of Austin on the outskirts of Buda.
2. The Effect of Large Bodies of Water: If you live near a lake, pond or ocean you'll notice a higher moisture level and humidity in the air. On the plus side, this can moderate temperatures of the surrounding area, but it also makes everything seem a little 'sticky.' The effects of this extra moisture are most pronounced in coastal areas and large lakes and can create its own weather, i.e. The Great Lakes region 'lake-effect' snow storms.
3. Cold air sinks: The higher you live on a hill, the warmer in general you will be relative to the valley beneath you. Even small hills can make a difference. One hard frost into the low 20’s saw agaves frozen solid at the bottom of a Round Rock street; those at the top of the hill had little damage.
4. Compass Points: Different sides of your home (or even a privacy fence) can have very different temperatures in both the summer and winter. Place plants that need cooler temps year round on the east or north side of the house where there will be afternoon shade. Put plants in need of extra winter protection on the west or south side. This way they'll get as much heat in the winter as possible and protection from the drying north winds.
5. Exposure: Plants growing in an exposed area will feel fluctuations in temperature more intensely than those set closer to a structure. For example, it's better to plant something with larger leaves that may suffer sunscald when facing west or south or damage from north winds along an opposite facing wall. It is also easier to offer plants some protection from afternoon summer heat by keeping them closer to a north or east facing wall, fence or even a taller plant.
6. Reflective surfaces: Lighter colors, including concrete, painted surfaces and limestone, reflect more heat than darker ones. In the summer this heat bouncing back onto a plant could burn sensitive leaves on a 100 degree day leaving them brown on the edges with pale, washed out spots in the inner areas. Alternatively, these same places can be a life-saver for tropical heat loving plants that need extra winter warmth and protection.
Armed with this knowledge, you should hopefully be able to add greater diversity to the collection of plants in your landscape as you explore the peaks, valleys and protected areas around your home. ❦
