Microclimates

Microclimates can be a little bit ambiguous. What are they? How do I use or create microclimates? Do they make much of a difference?

These are all valid questions that I want to answer today!

Let’s dive in.

Definition

Microclimates are defined as “The climate of a very small or restricted area, especially when this differs from the climate of the surrounding area” according to the dictionary.

Basically, they are small “pockets” where your climate differs a lot. For example, I live on the West side of Michigan about 30 minutes from the lake. Even though we are in the same climatic zone as someone right on the shore we get very different weather patterns.

I say this to explain that even within a local climate, there are variations. Microclimates are usually much smaller than that. Some of you know that I co-own a small urban farm. Well we originally had the farm at a friend’s house roughly 10 minutes south of where it is today, and the differences in growing conditions were surprising!

Not only were there different soil types and pests, but the southern location got frost almost consistently 2 weeks before we ever did in the current location.

For northern growers especially, this could make a huge difference in harvest sizes!

Elements of a Microclimate

There are a few main elements (and probably countless minor features) that define a microclimate:

Wind

What is the wind speed in your area? How much wind do you get per season? Wind changes the temperature. It can be a huge contributor to freezes and in some places cause damage to certain crops (looking at my kale from a few years back).

Moisture

The amount of moisture in the area whether that’s in the ground, rainfall, or humidity in the air. This effects potential floods, how often you’ll need to water your crops, and can also play a role in temperature fluctuations.

Natural Temperatures

The natural temperatures in an area are generally determined by the regional climate and larger features such as a lake or mountains, but in a microclimate can be affected by things like the placement and orientation of a house.

Elevation

Elevation can play a role in both temperature and the drainage of your site. It also affects what parts of the landscape will act as “cold sinks” and “heat sinks” (which I’ll explain later!)

Light

The amount of light you get in a given area changes the average temperature significantly as well as your water retention and growing habits.

Each of these are closely intertwined and interact with each other, but those are just the basic things to look for to signify a microclimate.

That said, there are ways you can manipulate your microclimate which is the main point of this article.

Here are the main tools you can use:

Rocks

Rocks act as a thermal “battery”. When they absorb heat, they release it slowly during colder parts of the day and the night. Placing these strategically around your garden can raise the minimum temperature significantly.

Vegetation

Not only can plants cool down an area, but in colder weather they can insulate it and keep it warmer as well. Additionally, larger plants can act as a windbreak to keep an area both safe from wind damage, and warmer.

The most common use for vegetation is to keep water from evaporating out of the soil. To do this, you’ll want to plant densely and make sure the soil is covered at all times. This can also reduce nutrient loss in your soils and encourage microbial life.

Water Bodies

Water bodies act as a thermal battery, but also as a means of storing water in the soil. This is especially important in hot climates where water retention is extremely important.

Water bodies also act to raise the ambient humidity in an area which can be useful if you’re trying to grow in a dry microclimate.

Earth Mass

Mounds of earth (hills, valleys) can be very important. They act as a thermal battery, but also redirect waterflow from one area to another.

When things are planted higher on a mound or hill, the soil drains better (similar to what you might see in a raised bed).

Mounds can be used strategically to raise the ambient temperature and block wind.

Mulch

You could say that vegetation is really just a living mulch, but for the sake of clarity I’m separating the two.

Mulch is something you use to cover the ground, and is made of organic matter. (This could be woodchips, leaves, hay, straw, dead plants, lawn clippings, or wool). Mulch covers the ground to keep water trapped in the soil, and to prevent nutrient loss.

As mulch breaks down, it actually adds nutrition to the soil and creates habitat for insects and microbes.

As farmer Joel Salatin says “nature is modest” so keep the ground covered with mulch!

It might be hard to picture how all of these things combined can actually make a significant difference. Afterall, if it’s normally 10°F and you manage to get your microclimate up to 13° that doesn’t really change how much you can grow.

Let’s look at some real world examples to show you how much of a difference microclimates can make when you combine some of these tools:

Moray, Peru

Moray is one of my favorite historical sites.

Moray is on a high plateau in Peru at about 11,500ft elevation. The Incas created large crater-like terraces where they would plant different crops. This site is widely considered to be an agricultural experiment station since the Incan empire stretched over many different climates.

This makes sense considering how much plant breeding they did.

Fun fact: The soil they use in the terraces is actually soil from down in the valley NOT from on top of the mountain meaning they had to haul all of it up by llama!

The most fascinating thing about this site though is the difference in temperature from the top terrace to the bottom. According to Kim MacQuarrie (historian and anthropologist) the temperature varies from 30°-50° from the top to the bottom!

For reference, this means that if it was below freezing, you could still have frost sensitive crops growing in the warmer parts. In other words, you could grow citrus in Michigan.

Notice how they took advantage of elevation, earth mass, rocks, and light.

Canary Island Vineyards

The Canary Islands (a Spanish archipelago off the coast of Morocco) have a unique traditional technique for growing grapes.

The climate here is harsh because of the strong winds that would otherwise kill almost any plant, but the locals have started growing grapes in small craters that dot the volcanic landscape.

Each crater is as much as 30ft wide and 10ft deep or more. This protects each plant from the prevailing winds, and allows some water catchment.

In an otherwise un-farmable climate, making use of microclimates has allowed for vineyards to exist.

These vineyards take advantage of light, earth mass, rocks, and maximize moisture.

ABC Acres, Montana

ABC Acres is a permaculture-based farm in Hamilton, Montana.

The farmers there have several really fascinating systems (including a passive greenhouse that grows bananas, papaya, and pineapple among other things) but today we’ll focus mostly on the crater garden.

In a similar fashion to Moray, Peru, ABC Acres has created a terraced crater. However, unlike Moray, this one has a large pond in the center.

The pond and rocks act as a thermal mass that keeps the terraces warm enough to grow plants from zones 5-6 in zone 4 which is pretty impressive!

The taller side of the crater has 4 terraces which also act as a thermal mass, and the hillside being covered with vegetation undoubtedly insulates that warmth further.

By using these few techniques in tandem, they are effectively pushing their growing zone by 2 or more which is an impressive feat!

Tools used: Rocks, Water body, Earth mass, light, and vegetation.

If you’d like to visit, you can book a farm stay here: Book a Stay

LEAD Foundation

The LEAD Foundation is a conservation organization that specializes in ecological restoration but with a twist: They train farmers how to regenerate land and do community development.

The main example of a microclimate in action is pictured above. These are called “bunds”.

Bunds are half-moon mounds that are placed to catch water that normally would run off of the landscape (think like a mini-swale). These bunds are powerful enough to actually reverse desertification in arid climates and similar restoration projects are happening in India.

By catching water, the bund not only makes plant life possible within the crescent, but it stores nutrients and slowly releases that water out into the rest of the landscape without eroding it.

The LEAD Foundation website can be found here: LEAD Foundation

Give them a follow on Instagram too! @Lead.tz

The main elements used with these bunds are earth mass, moisture, and the vegetation that follows.

Herb Spirals

Let’s look at a few more basic techniques that you can use in your garden.

An herb spiral is a concept developed by Bill Mollison to grow herbs in a three dimensional garden bed.

The idea is that due to the orientation and elevation of the different parts of the bed, different herbs can thrive in the same spot.

Wikipedia describes this best, so I’ll quote here:

This is a great example of a very tiny microclimate group at max efficiency.

Elements used: Rocks, Vegetation, Earth Mass, Water body

Sun Traps

A sun trap is a garden layout that uses taller plants to insulate a pocket of warmth and catch sunlight.

On the outer edges you have the taller trees and shrubs with the opening towards the south for full sun exposure.

Then on the inside, you can plant your main garden where things can stay warm and insulated. On top of insulating and absorbing sunlight, this also provides a windbreak which would otherwise cool down the area.

This is a pretty common technique in permaculture where appropriate, and using this in combination with other strategies can drastically change your microclimate for growing in!

Elements used: Vegetation, mulch

Final Note:

I hope these were inspiring to you and that you at least grasp the basics of what a microclimate is and why they can be so powerful!

I want to also emphasize that not all of these methods will work in every region! Your techniques should be site-appropriate.

Always remember to go back to the 12 Principles and observe everything to figure out what makes the most sense and don’t be afraid to experiment! (While issues can arise from mis-applying a technique, that’s how we learn!)

You can read all previous publications here: The Naturalist

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