How to Get Started with Warm Microclimates
Creating warm microclimates is a great way to push the bounds of what you can grow on your property. This is also a great way to create a longer growing season and get more harvests. But there are downsides to creating warm microclimates, especially in a warming world. Let’s dive into warm microclimates and how to use them.
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Have you ever wanted to grow something that is outside of your climate zone? I know I have. I would love to grow citrus—or even a banana!—here in western Washington! But as fun as that could be, the biggest advantage of creating a warm microclimate is being able to extend your growing season by a week or 2 in the spring and in the fall.
This might not seem like a lot, but that equals a half month to a full month of fresh veggies from your garden!
Plus, a warm microclimate can make it easier to grow cold-hardy vegetables through the winter, outside your normal growing season.
But warm microclimates can also increase the need for watering and make it harder to grow some vegetables. Spinach, for example, will bolt (go to seed) if it gets too warm. Other vegetables, like snap peas and lettuce, also don’t like the heat.
The key is to balance the use of warm microclimates with cool microclimates, depending on what you’re trying to grow. To help you do this, make sure to check out the cool microclimates blog post that goes along with this post on warm microclimates.
Get started with microclimates on your property.
- 1How to Get Started with Warm Microclimates - current post
- 2How to Get Started with Cool microclimates
Just keep in mind that more intense heatwaves and droughts are likely to become more common in the future in a warming world, so don’t go overboard with warm microclimates—especially if you want to grow cool-loving vegetables!
So are you ready to get started with warm microclimates? Let’s dive into some basic types of warm microclimates to help you extend your growing season and get more harvests.
But before you scroll on down, make sure to grab your free and easy-to-print cheat-sheet all about microclimates—hot and cold! This cheat-sheet will help you get started with both types of microclimates.
Constructed Warm Microclimates – Raised Beds and Walls
One way to create warm microclimates is to construct them. A classic way to do this is to build raised beds. But you can also take advantage of existing structures, such as your house, shed, or stone walls.
The south side of a stone wall or building (or north side in the southern hemisphere) will create a nice warm microclimate. This is the result of heat radiating from the structure/wall, sunlight reflecting off the structure, and the blocking of cold northern winds (or southern winds in the southern hemisphere).
Before greenhouses were common, the use of stone walls for creating warm microclimates was a common practice in temperate regions such as Great Britain. Some were even heated with fire!
Large stones can also create warm microclimates by reflecting sunlight and radiating collected heat. Rocks can also double as habitat features to support predators of common garden pests.
Raised beds are also a great way to create warm microclimates for your garden. Cold air flows just like a liquid, and it will “pool” on the ground. Raised beds keep your plants above this cold air, resulting in a relatively warm microclimate.
These types of garden beds also have more surface area exposed to the air and sun. While this helps them to absorb heat during the day, they also tend to dry out quicker.
You can also angle the surface of your beds towards the sun to further enhance your warm microclimate. But again, this will also make the beds more prone to drying out.
This is a classic example of the tradeoffs of creating warm microclimates. But you can mulch the surface of your raised beds and build the beds using thick walls (logs or stone) to minimize this impact while still creating a relatively warm microclimate.
Summary - Constructed Warm Microclimates:
Placing new garden beds on the south side of structures and stone walls, (the north side in the southern hemisphere,) or creating raised beds, are all great ways to create warm microclimates. But the resulting garden beds will dry out more quickly and may be too warm for cool loving vegetables—at least in the summer.
Blocking Wind and Cold Air
While structures and walls are great ways to create warm microclimates, there are ways to use plants themselves to create these microclimates.
As mentioned in the previous section, cold air flows like a liquid over the land. Cold air is denser than hot air, so it sinks down to the surface and collects in areas just like a liquid would.
This means that you can use taller plants to create sheltered areas below them that are warmer than the surrounding area in the winter.
The cold air is essentially deflected, just like rain hitting an umbrella as it falls towards the ground. The result is an area under the tall plant that is a bit warmer.
To get the most out of this method, plant your tall plants so they don’t block the sun. Tall trees planted on the north side (or southern side in the southern hemisphere) can block cold air while still letting in sunlight.
Look under your trees or take a walk in the woods next time you get a frost and you should see this affect.
Cold air also flows downhill once it reaches the ground. One important aspect of creating relatively warm microclimates is to avoid creating frost pockets.
Walls, structures, and rows of plants can all cause the cold air to build up on the uphill side of them. This results in a cold area on the uphill side and a warmer area on the downhill side.
Plants planted on contour (on a level line) will trap the most cold air. Plants planted off contour will cause the cold air to flow along the plants downhill, without creating a frost trap. You can direct the flow of cold air around your property just like you would direct the flow of water.
You can use this pattern to your advantage by planting shrubs and trees that will deflect cold air around your vegetable garden.
Your garden will end up in a nice, sheltered, warm microclimate.
The same can be done to block cold winds.
Cold winds come from the north, (or from the south in the southern hemisphere,) so a hedgerow planted along the north side of your garden will deflect the wind over and around your garden. The taller the wind block, the bigger the sheltered area will be.
Summary - Blocking Wind and Cold Air:
Cold air flows like a liquid and is denser than hot air, so it pools on the ground. Plant your plants so they deflect the cold air around your more sensitive plants, such as your vegetables.
Cold winds can also be blocked by planting tall wind blocks or hedgerows.
The result will be relatively warm microclimates in the sheltered areas, created by your shrubs and trees.
Making the Most of Warm Microclimates
Creating warm microclimates is a great way to extend your growing season and potentially grow plants outside their normal climate zone.
Check out the book Push the Zone: The Good Guide to Growing Tropical Plants Beyond the Tropics by David the Good for more tips and strategies for creating warm microclimates.
But you also need to be careful not to create situations where your gardens—and your property as a whole—are vulnerable to drought.
You want to moderate the extremes.
Here are some great options for you to take advantage of warm microclimates while minimizing the negative impacts.
- Apply mulch to your garden beds. This will also keep your soil from freezing. But mulching will also keep your soil cool in the spring.
- Build hugelkultur beds so you get the advantages of raised garden beds while also reducing your watering needs.
- Place small logs on the sunny side of your plants to keep the base of the plants cool during the day.
My final tip for you when it comes to warm microclimates is to think about what you’re wanting to grow.
If you’re wanting to grow a plant that normally would not do well in your climate (say, citrus in western Washington,) then you will need to use every method you can to create a warm microclimate.
But if you’re just wanting to extend your growing season, then small changes can make a big difference. Placing a garden bed for tomatoes on the south side of your house (or north side in the southern hemisphere) is a great and relatively simple option, even if your main garden is in a different area.
Making all your garden beds into raised beds is another.
With these relatively simple adjustments, you will create relatively warm microclimates that give you days—or even a couple weeks—of additional growing time in the spring and fall.
That can result in a lot more fresh veggies for your family and community—without even needing a greenhouse!
How have you used warm microclimates on your property? (Or how do you want to?) Leave a comment to let us know!
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