By Pat Dray
The Garden Spot
Pat Dray
You may have heard the term microclimate used to describe a small area that has a different set of atmospheric conditions than the greater surrounding area. This term can be applied to an area several square miles, or as small as a garden bed.
An obvious example of a microclimate is a parking lot. It’s noticeable how much hotter the paved areas are than those with vegetation. Other examples are places near bodies of water which may cool the local atmosphere, or urban areas where brick, concrete and asphalt absorb the sun’s energy, heat up and re-radiate that heat to the ambient air.
My yard is its own microclimate, with its location across from the Housatonic River and wind rushing down the valley resulting in cooler spring temperatures. My forsythia actually blooms a week or so later than those of my neighbor across the street.
How you manage your property can affect the microclimate and make it either hotter or cooler. For example, wet soil will absorb twice as much solar energy as dry soil, since water absorbs about four times as much energy as soil. Stone and concrete absorb about twice as much solar energy as soil, while black surfaces and materials absorb 35 percent more solar energy than white surfaces.
You may be creating “heat traps” and changing your microclimate when you expand the driveway with asphalt and put in a stone patio. Because plants, and the pollinators that are attracted to them, are very slow to adapt to changes in temperature, you may start to see different plants thrive in those newly hotter areas.
If you do have a heat trap in your garden, you can take the following steps:
- Watering your plants in the early morning is the best option before the sun starts shining brightly on your plants. If you water later in the day, you risk the water evaporating before it makes it to the plant’s roots, causing the leaves to burn.
- Keeping your lawn at least 3 inches long can add shade to the grass, which will help retain moisture in the soil.
- Take advantage of nearby structures as heat sinks and natural covers. Fences, boulders and shrubs can serve a protective function for nearby plantings. Trees surrounding your garden can act like a blanket and reduce the amount of heat radiating from the soil, potentially keeping the temperature high enough to protect your plants from early fall frosts.
- Mulching around your plants can help keep moisture in the soil and reduce evaporation.
- Keep hard, impervious dark surfaces to a minimum.
Happy gardening.