December 2016 Tip of the Month: What Are Microclimates… And How Do You Use Them In Your Garden Or Edible Landscape?

If you’re a gardener, you’re probably familiar with agricultural zones, first/last frost dates, and plant hardiness (that’s why you wouldn’t try to grow a tangerine tree outdoors in Ohio).

But you might not be familiar with “microclimates.” What are 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.

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.

Simply put: 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

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!

And there can also be small microclimates, right within your own yard, that offer unique conditions: warmer, colder, more moist, more dry, more sun, more shade.

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:

    • Large rocks, driveways, and sidewalks – Do you have a large boulder, rock, concrete driveway or sidewalk in your yard. These absorb heat from the sun during the day and slowly release that 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.
The large rocks on the front of this bed absorb a lot of heat on a sunny day, and radiate that heat back into the bed at night. This means the soil stays a few degrees warmer than in surrounding areas.

The large rocks on the front of this bed absorb a lot of heat on a sunny day, and radiate that heat back into the bed at night. This means the soil stays a few degrees warmer than in surrounding areas.

    • 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 landscaped” beds.
    • 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, corn, horseradish, and others. However, in the fall & 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 cole crops, chickweed, claytonia, carrots, and other cold-weather goodies.
The garden bed on the west-facing side of our house in the summer. Loaded with heat and sun-loving plants like zinnias (to attract and feed pollinators like this Monarch butterfly) and edible plants too.

The garden bed on the west-facing side of our house in the summer. Loaded with heat and sun-loving plants like zinnias (to attract and feed pollinators like this Monarch butterfly) and edible plants too.

The same west-facing garden bed in the winter. In this photo, we've pulled the plastic from the lowtunnel/polytunnel off since the temps went over 50 degrees so that the plants underneath don't get too warm. The wall of the house provides additional heat and reflects the rays from the sun back onto the bed.

The same west-facing garden bed in the winter. In this photo, we’ve pulled the plastic from the low tunnels off since the temps went over 50 degrees so that the plants underneath don’t get too warm. The wall of the house provides additional heat and reflects the rays from the sun back onto the bed.

    • 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 take the heat. Fiddlehead ferns and heat-sensitive salad greens that would wilt in the afternoon sun will also grow well here in the spring/summer.
Young

Young “fiddles” of a fiddlehead fern (Matteuccia struthiopteris) emerging in the spring. These are growing in the beds immediately next to the east-facing wall of our home (morning sun, afternoon shade). Many varieties of ferns do NOT produce edible fiddles, so be careful you know which varieties do if you intend to plant them for an edible garden. And also be sure to cook them properly.

    • North-Facing House Wall – The garden areas next to a north-facing wall might only get 4-5 hours of direct sun in the summer and two in the winter. Less sun will usually mean more moisture as well (less evaporation). There are long lists of edible plants that can grow in part-full shade. Our friend Marie Viljoen at the 66 Square Feet Blog has a great list of shade-loving edible plants published on Gardenista. (She gardens year round in New York City in a spot that’s almost full shade in the winter!)
    • 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 – 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.
When we moved into our home, there was a severe slope in our backyard with poor compacted soil that was covered in poison ivy and kudzu. To prevent water and nutrient runoff, we built dry-stacked stone walls made from discarded rocks from a nearby housing development. As a north-facing slope, this is one of the coolest spots in our yard. During the cold months, we grow loads of edible plants under polytunnels on the now-terraced slope.

When we moved into our home, there was a severe slope in our backyard with poor compacted soil that was covered in poison ivy and kudzu. To prevent water and nutrient runoff, we built dry-stacked stone walls made from discarded rocks from a nearby housing development. As a north-facing slope, this is one of the coolest spots in our yard. During the cold months, we grow loads of edible plants under low tunnels on the now-terraced slope.

  • 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 anywhere near your dinner plate, so plan accordingly.

Next Steps: Identify 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 that will also help you.)

We’d suggest taking out a sheet of paper to “map” your property. Make sure to put in your cardinal directions (north, south, east, west) then walk your property making notes on your map as to which direction your planting areas are facing towards the sun, whether they’re on a slope, in a low area, etc.. Pretty much every smart phone has a compass on it, to make this process easier. 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.)

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.

Experimentation is the goal; trial and error are the expectation. Let us hammer that home: mistakes = learning opportunities, so 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.

Happy gardening!

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