For gardeners, there’s always more to learn. Just when you think you’ve learned all the vocabulary you can handle, you hear the term microclimate. So, what is a microclimate, you wonder?
Will it involve another USDA-like zoning map or a fancy Latin plant name? No. It’s a simple concept that opens up more possibilities for growing plants in an environment in which they’ll thrive and flourish.
Here’s your primer on microclimates:
- What is a microclimate?
- Which features help create microclimates?
- Effects of microclimates on plants
- Microclimates in urban areas
What is a microclimate?
Just what it sounds like: It’s the climate in a micro or small area, such as the immediate area around a plant, instead of a larger one, like a city or state.
So, what is climate, exactly? Is it the weather in an area? Almost. Weather is what you experience in a day; climate is how atmospheric conditions act, on average, over tens, hundreds, or thousands of years.
Features such as average temperature, rain, humidity, and wind make up a weather forecast. For example, there may be rainy weather in today’s forecast in Southwest Arizona.
Those same features averaged together over time make up the local climate. For example, rainy weather today in Southwest Arizona doesn’t make for a rainy climate. This area receives about 3 inches of annual rainfall and, therefore, has a dry climate. This overall climate is determined by weather data collected over a long span of time.
Which features help create microclimates?
Now we know about climate and weather in large areas, such as Southwest Arizona, so how does that apply to your landscape?
Here are a few features that help create small or microclimates in your landscape:
- Roofs
- Walls
- Walkways
- Fences
- Balconies
- Other built features, such as porches, patios, and pergolas
- Hills, berms, valleys, and other landforms
- Orientation to the sun (north, south, east, west)
- Shade
- Trees and vegetation
- Hoop houses
- Soil type
- Ponds and bodies of water
A hoop house is the most obvious of these examples. A hoop house is a portable greenhouse that keeps the plants warmer inside than the outside surrounding area. It also shields plants from snow and rain. A hoop house has its own microclimate that is separate from the climate just outside its walls.
Effects of microclimates on plants
What effect do these features have on the microclimates in your yard? Here are a few ways these features create different, mini-climates in your lawn:
Precipitation
Wouldn’t it be nice to control the rain? If you create a microclimate, you can.
Hanging baskets in a roofed gazebo, for example, enjoy protection from rain or snow. For plants that prefer drier conditions, a gazebo creates a more comfortable microclimate for them, even when the surrounding area is getting soaked with rain.
Sun and shade
The amount of sunlight your plants receive is critical for proper growth. Plants facing south get more sun than plants that face any other direction. Plants on the west side of the lawn will get afternoon sun, which may be too harsh for some plants; east-facing plants get softer morning light.
Planting under an overhang, shade cloth, or tree canopy limits the amount of sunlight for plants that prefer shade.
Pro Tip: Have your full-sun winter plants on a south-facing slope for maximum sunlight.
Wind
You may not be able to control the wind like Aeolus, but you can observe the wind patterns in your yard and take precautions. Install more delicate plants outside of any windy areas in your yard. If you can’t avoid the winds, install these plants behind a hedge, fence, or trellis, or against a wall to create a natural windbreak. If needed, stake them for extra support.
Air temperature
Short of growing in a greenhouse, there are a few ways to create warmer or cooler microclimates for sensitive plants.
Plants that grow against walls, walkways, or other hard surfaces receive more heat than a plant on open ground. Conversely, plants that chill out on your covered porch will enjoy cooler temperatures than if they were exposed to the sun.
Another example: Hoop houses can be used year-round but are most often used in areas with cold winter climates to protect tender plants from frost, freeze, and cold air.
Evaporation
Ever put mulch down to reduce evaporation? You’ve created a microclimate. Planting in areas with more or less shade, mulch, or ground cover affects how much water evaporates from the soil into the air.
Microclimates in urban areas
Until now, we’ve discussed small-scale microclimates that you’d find in a suburban or rural home setting, but large areas like cities have microclimates, too.
Ever heard of an urban heat island? It’s a type of urban microclimate. An urban heat island is when temperatures in an urban area are significantly warmer than the surrounding regional climate. What’s behind this phenomenon? Here’s a quick comparison.
Urban heat islands vs. nearby rural areas:
- Less greenery, plants, grass, and tree cover
- More impermeable surfaces (less evaporative cooling from the soil)
- More dark surfaces (roofs, tall buildings, roads)
How do these features create a heat island?
- Less transpiration
Plants pull water up from their roots and transpire, or release, the water from openings in their leaves. This creates a cooling effect for the surrounding area, like air conditioning for the great outdoors.
- More heat absorption
Dark surfaces absorb sunlight. This means the roads and buildings in a city convert this sunlight into heat, creating higher air temperatures. Grass and plants don’t absorb as much sunlight (they’re more reflective) and, therefore, create less heat than a dark surface.
How cities creatively combat these problems
- Rooftop gardens
Rooftop gardens not only incorporate more greenery, creating more transpiration (and cooling) for cities, but by covering a usually dark surface with greens and browns, it releases less heat, as well.
- Painted surfaces
Some cities have opted to paint black surfaces with a lighter, reflective coating. This may sound like a lot of trouble, but it has a significant effect on air temps (and energy costs) during hot summer days.
- Alternative paving solutions
Roadways and sidewalks contribute to higher air temps and higher energy costs, among other issues. Cities are considering other paving options, such as cool pavements, permeable pavements and pavers, and other new technologies.
These new construction materials may help reduce air temperatures and water pollution, cool and reduce runoff, recharge groundwater, and reduce drainage issues and flooding.
In sum, these solutions mean less sweat for you and less drain (literally) on the city infrastructure.
If your lawn’s microclimates aren’t in top shape, let one of Lawn Love’s lawn care experts come to the rescue. They’ll help ensure your lawn has the conditions it needs to thrive.
Main Photo Credit: Tony Alter | Flickr | CC BY 2.0
