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What are microclimates? Understanding what microclimates are and how they work can have a dramatic impact on your gardening success.
If you’re a gardener, you’re probably familiar with agricultural zones, first/last frost dates, and plant hardiness. Knowing this information keeps you from trying to grow tomatoes outdoors in Ohio in December.
But you might not be familiar with “microclimates.”
This image was taken in the Santa Monica Mountains in California. Notice the north-facing slope (left) is covered in white-blooming hoaryleaf ceanothus, while the south-facing slope (right) is much less sparsely vegetated in completely different species of plants. What accounts for these differences? Microclimates. Image credit: By Noah Elhardt – Image taken by Noah Elhardt using a Sony DSC-s70 digital camera., CC BY-SA 2.5, Link
What are microclimates?
Microclimates are areas that offer unique growing conditions relative to the broader agricultural zone where they’re located.
There can be large microclimates, such as an entire city, a north-facing slope, or a valley that’s much cooler or more moist than the surrounding area.
Cities create large microclimates due to the “heat island effect.” We live about 10 miles from a city and it’s almost always a few degrees warmer in the city versus where we live. It’s interesting to see the trees start to leaf out in the spring 10-14 days ahead of ours due to the difference in climate. This year, our first killing freeze arrived three weeks BEFORE our friend’s who garden in the city! Image credit: By Urban_heat_island.svg: TheNewPhobia derivative work: Alexchris (talk) – Urban_heat_island.svg, Public Domain, Link
There can also be small microclimates right within your own yard that offer unique conditions: warmer, colder, wetter, dryer, sunnier, shadier, etc…
Knowing the microclimates in your yard can make a huge difference to your success as a gardener. Selecting edible plants that prefer the unique conditions of a specific microclimate will mean better yields and less effort.
Selecting Plants for Your Microclimates
Here are some examples of microclimates and plants you could select for those climates:
Microclimate: Large rocks, driveways, and sidewalks
Do you have a large boulder, rock, concrete driveway or sidewalk in your yard?
These dense surfaces/objects absorb heat from the sun during the day and slowly release their heat at night, making the ground immediately around them warmer (and potentially dryer if there’s not much rain). This means you could potentially extend the growing season of plants placed immediately next to them or put in plants that like more heat and dryer soil.
Microclimate: South-Facing House Wall
The front, south-facing exterior walls of our house get first sun and stay warm throughout the day. Certain plants that might not normally grow well in our Ag Zone due to it being too cold (example: pineapple guava) do fine when planted near these walls due to the additional heat.
We’re also able to extend our growing seasons for our annual plants in these “edible landscape” beds.
Microclimate: West-Facing House Wall
The west-facing wall of our house gets early morning shade and then gets blasted with afternoon sun that’s made even warmer and brighter by the radiative heat and light reflected off of the siding. In the summer, we put in plants that can handle the intense heat and light of the afternoon sun: sunflowers, zinnias, garden huckleberries, eggplants, corn, horseradish, and others.
However, in the fall and winter, the morning sun gets to this spot a little earlier and the extra heat helps keep our garden beds here 5-10 degrees warmer than other spots on a sunny day. We also use low tunnels during the cold months on this side of the house to bump up the temperatures even further for our cold weather crops.
Microclimate: East-Facing House Wall
Need a spot to put plants that like morning sun and afternoon shade?
Put them next to your east-facing wall. For folks living in the south, this might allow you to plant rhubarb or other plants that would not typically be able to tolerate the heat. Heat-sensitive salad greens that would wilt in the afternoon sun will also grow well here in the spring/summer.
Microclimate: North-Facing House Wall
Due to a forest and large hill behind our home that blocks the late afternoon sun, the garden areas next to our north-facing house wall only get 4-5 hours of direct sun in the summer and two in the winter. Less sun also means more moisture as well (less evaporation).
What edible plants can be grown in part to full-sun spots? We’ve created a comprehensive list of edible shade plants here.
Microclimate: Low Spots
Need a spot for a plant that likes “wet feet,” e.g. moist soil? Find your low spots. Celery, celeriac, Alexander, parsley, chickweed – all love lots of moisture and grow well during the cool months of spring and fall.
Slopes tend to have poorer soil and lower soil moisture since water and nutrients run off downhill, rather than staying put (unless you have plants to stop the flow or you construct swales or terraces).
Slopes can be either hotter or colder, depending on which direction they face relative to the sun. Generally speaking, deep-rooted plants and/or perennials are best for slopes since their roots can run deep to mine nutrition, stabilize the landscape, and avoid toppling over during heavy rains. Chicory, comfrey, fruit & nut trees – all can perform multiple functions on a slope.
If you want to see one of the most dramatic and amazing transformations of a heavily degraded, sloped landscape, check out this 13 minute video showing how permaculture design transformed 8.6 million sloped acres in China’s Loess Plateau region.
Microclimates: Creeks, Boggy Spots, Ponds
It goes without saying that these microclimates are much wetter than other spots might be in your yard/property, and often a bit cooler as well. But that certainly doesn’t mean you can’t grow edible plants in them.
True wasabi is a naturally green delicacy and the less expensive “wasabi” you get at most Japanese restaurants is made from dyed horseradish, not actual wasabi. Cattails offer a wide array of delicious edible parts. (Interesting fact: cattails can produce more edible starch per acre than any other plant!) Water lilies and lotuses both produce edible leaves, flowers, seeds, and rhizomes – the rhizomes are considered a gourmet delicacy and often featured in Asian cuisine.
There are far too many other edible water plants to list here. Do keep in mind that many waterways are often polluted with contaminants and runoff that you don’t want on your dinner plate, so plan accordingly.
Next steps in identifying and planting your microclimates
What to do next now that you know about microclimates?
As permaculture advocates, we’re big on the principle of Observing and Interacting with the areas you’re going to be growing food in. (Here are the 12 basic permaculture principles if you’re interested.)
2. Map & Note
During observation, we’d suggest taking out a sheet of paper to start mapping your property. Make sure to put in your cardinal directions (north, south, east, west). Then walk your property making notes on your map…
Which planting areas are facing towards the sun? Which are on a slope? In a low area?
If you need some help getting oriented, pretty much every smart phone has a compass on it. You can also use mobile apps like Sun Seeker or SunSurveyor to see how much direct sun a certain spot will get at a specific time/date of the year.
If you live in an area that gets snow, a great low tech way to tell what spots in your yard are warmer and colder is to observe where the snow melts first to last. (Eliza, GrowJourney’s Education Director, has a great article on her blog about this.)
3. Create a plant list
Once you have a good idea of your microclimates, you can create a list of edible plants you’d like to try in each spot at different times of the year.
4. Get started now
Experimentation is the goal; trial and error are the expectation.
Let us hammer that point home: mistakes = learning opportunities. The more you try, the more you’ll learn. And over time, you’ll learn how to expertly use your microclimates to yield amazing edible results throughout your garden or edible landscape.