Have you ever noticed an area of your yard that is always the last place the snow melts in spring? Or how the daffodils in one bed are up and blooming before the rest of the daffodils in the yard make an appearance? Chances are these are microclimates on your property. Microclimates are just what the word implies, small areas where the climate differs from the surrounding areas. It may be colder or warmer, a frost pocket or insulated, even drier or wetter than the rest of the yard.
The area can be small, like a south facing spot in front of a cement wall that gets a lot of radiant heat, or they can be an entire valley, where the cool air collects or the way a concrete city is at least a zone warmer than the surrounding countryside.
What Microclimates Mean for Your Garden
As a gardener, you should pay attention to microclimates within your own yard and you will start to notice them the more you garden. We all try to plant according to our hardiness zones, but there are places in every yard where some plants that shouldn’t survive winter in your area do and other places where plants you would have thought would be hardy, die. Your yard could be considered a zone 6a, but parts could be 5b or even a 7. Definitely something worth taking advantage of.
Knowing where these microclimates are can be a great advantage to a gardener. Areas that thaw out and warm up first in spring are where you should plant your tender perennials. If you have a spot where water collects, you can improve the drainage or create a bog garden.
If you’d rather change microclimates than work with them, that’s possible, too. You’re not stuck with whatever microclimates currently exist. Some examples would be: if water doesn’t drain well, you could amend the soil to make it more permeable or alter the slope of the land to to encourage better drainage. Frost pockets can be opened to more sunlight by trimming up trees and wind blocks will create sheltered pockets.
Locating Existing Microclimates
Microclimates are usually caused by some type of structure or material that impacts how much the natural elements, such as sun, wind and water, affect the area. Some conditions to look for include:
Wall and Fences
Any large structure, including the walls of your house, will absorb and hold heat during the day and then radiate it back at night. Different materials will absorb to varying degrees, for instance, a cement wall will absorb a great deal of heat while a picket fence will offer minimal heat.
Generally, the south and west sides of the house will get the most sunlight and provide the most sheltered growing area. That may be great in the spring when you want things to start growing, but it can also bake plants in the heat of summer.
North facing walls sit in shade most of the winter and can hold onto their frost well into spring.
Terraces, balconies, hilltops, and even raised beds tend to warm up earlier than low lying areas. And since frost tends to settle, they can remain frost free later in the fall. However, they are also subject to winds, which can be cold and desiccating.
If you’ve ever spent time standing on a driveway in the hot sun, you know how much heat paved areas radiate. I have often planted melons along a walkway, to take advantage of the extra warmth. You could create the same effect by placing flat stones in your vegetable garden.
Whether you are dealing with existing microclimates or trying to create your own sheltered spot, observation is key. Keep an eye on the plants throughout the year and be prepared to make adjustments or even remove or replace plants, as needed.