Microclimates and Other Weather Effects

Microclimates are something that every garden has.  Microclimates are areas of your yard where the temperature is affected by the landscape. This includes the grade/elevation, any prevailing winds and wind speeds, the presence/absence of standing water, etc.  

Growing Plants and Elevationhills

Hills are more exposed than other microclimates. These microclimates are generally colder than flat surfaces. Ravines or dells are more insulated, so they can be warmer on average than either of the previous situations.  So if you are in a Zone 4 climate, your hilltops may be on the colder end.  Any ravines or dells may be more sheltered, and you may be able to experiment with more Zone 4A or even Zone 5 plants there.  Keep in mind experimenting with higher zone plants has the possibility of failure.

Wind’s Impact on Growing Plants

Knowing your prevailing winds and their average speeds can help you plan the microclimates your garden for success.  South and West winds are generally going to be warmer than North and weathervaneship12East winds, for example.  

Faster wind speeds will have a cooling and drying effect on areas experiencing them, as the wind pulls water out of the plants through evaporation.  The point at which damage occurs can be hard to predict, since different plants can take more or less wind.  If you can notice a significant wind coming through pretty steadily, please take it into consideration when you are doing your planting.

For example, if you have a corner of your garden with a prevailing Northeast wind, and a noticeably brisk speed, you will have a significantly cooler climate there.  If you have an area with a strong Southwest wind, you may have a very hot and dry area to plant!  

You can try to soften the blows by planting in masses and using larger shrubs and woody

windbreakdiagram

Diagram of Appropriate Windbreak Design (worldofagroforestry.org)

perennials as windbreaks.  By forcing the winds through other, stronger plants, you can mitigate the speed and to some extent (not 100%) the direction, as having a large planting insulates significantly and can keep more moisture to itself than an isolated single plant, surrounded by hot or cold air.

 

Standing Water and Its Effects on Microclimates

gardenpondStanding surface water can have a significant impact on your garden’s temperature.  Any presence of standing surface water has a cooling effect in summer, since water is constantly evaporating into the atmosphere.  It also has an insulating effect, keeping temperatures more stable and moderate, and less prone to spiking with heat or cold.  These areas may take longer to warm up in spring and cool down in fall.  The effects vary with the size of the body of water, so expect small buffering from smaller ponds (and possibly still temperature spikes), and a larger ‘calming’ effect from larger ponds or small lakes.  

If you live near a large enough body of wlakeater (like a very large lake or even ocean) you may also see significantly more snow, due to what is called the ‘Lake Effect’.  Since plants see snow as a great insulator against winter temperatures. More snow is not usually a concern from the plants’ point of view – they don’t have to shovel!  

Snow weight might be concerning if you have delicate or new woody plants or trees, so be sure to watch any build-up carefully, and remove when it becomes too heavy to prevent limb breakage.

Climate Change and Global Warming Effect on Growing Plants

globaltemp1nasagiss

(From NASA GISS)

As our global climate changes, our growing zones have begun to shift as well.  The USDA is continuing to collect data and research, and updating the map as needed.  However, what’s becoming more common is temperature swings. So extreme and abnormal temperatures have been recorded more frequently.  

Cold Snaps and Heat waves are something gardeners must always be prepared for. That’s because the Hardiness Zone map does not take them into consideration. Winter mulch is recommended for any tender or newly-planted areas. Plants appreciate shade and water in extra hot summers.  Being prepared for extremes always increases survival rate. It’s hard to be able to predict whether or not you’ll need preparations. But it’s better to be prepared rather than sorry!  

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Heucherella ‘Solar Eclipse’

If you have new plantings, remember to give them a little extra TLC, as mentioned in the previous paragraph.  Extra water, shade, mulch, and attention are all good ideas.  Baby plants need some, well, babying.  They haven’t stretched their thirsty roots out very far yet. and their leaves and crowns may be used to greenhouse conditions and not the ground freezing solid quite yet.  A little care goes a long way to set them up for future success!