The climate you live in largely determines what you can grow and when you can grow it. Most of us have heard of the United States Department of Agriculture climate zones. Those numbers that come on the packets of every seed packet serve to remind us that we´ll be hard pressed to grow peaches in Michigan or lemons in Maine. By learning how to take advantage of the natural elements around us, however, we can design microclimates which allow us to significantly increase the diversity of plants we can grow in any given region.
The Myth of Growing Zones
For some reason or other, most of us steadfastly believe in the certainty of climate zones. If the seed packet or nursery tells us that a certain plant is only hardy up to zone 8 and we live in zone 6, most of us will simply avoid that plant. The problem is that diversity is what allows for the greatest amount of resiliency in any sort of ecosystem. The more diverse a system is, the better chance it has to be sustainable and offer us quality yields.
While some plants require a certain high heat temperature in order to grow and fruit, others have a minimum number of cold hours that are needed if the plant is to grow adequately. In any given growing zone, however, there are hundreds of contextual situations that can affect the exact climate of a region. If you live in a mountainous region, the windward and leeward facing slopes present two completely different climate zones. Similarly, a small valley in a hilly region can significantly change the climate and subsequently what can be grown in that region.
While growing zones or climate zones do offer a good general picture to help you understand where you are at, they simply aren´t detailed enough to allow you to determine what exactly can be grown in a certain area. For example, while most of the state of Kentucky may be listed as zone 7, there may very well be areas in certain landscapes that could be considered to be adept for growing plants that are best suited for zones 8 or 9.
Human design can also affect the climate of any region. While global climate change is a rather unfortunate example of how humans can (negatively) affect the climate, it is also possible to conscientiously design landscapes to make them warmer or cooler for our growing purposes.
What are Microclimates?
Microclimates are spaces in any given landscape where the temperature and climate significantly differ from the immediate surroundings. Microclimates occur naturally in the natural world and can also be created through human design. They depend on the concentration of certain natural elements in specific places.
For example, it is well known that the sun causes warmth. An area in a landscape where the sun shines most brightly will most likely be warmer than the area in the landscape where sunlight is less intensive. Similarly, the wind is known to cool things off. Wherever wind is most present on a landscape, we should expect that part of the landscape to be significantly cooler. On a one acre parcel of land, the average temperature may vary up to 10 degrees Fahrenheit from one part of the land to the next based on the microclimates that exist.
One of the best ways to identify naturally occurring microclimates is through observation of the behaviors of our pets and/or farm animals. On a cold winter day, our house cat will most likely search out a part of the landscape where any sort of heat is most available. On a hot sunny day, our sheep, unfortunately, covered in thick wool, will naturally gravitate towards any place that offers a respite from the heat.
Once you have identified potential microclimate zones, it is possible to corroborate those findings with the help of scientific observation and data collection. A simple thermometer placed on different parts of your land will let you know the differences in temperature from one area to the next. Similarly, a wind gauge will also let you know where the wind is most prevalent in your landscape.
The Case of Sepp Holzer in Austria
Sepp Holzer is a permaculture farmer in Austria. His farm is located at over 1,500 meters in the Austrian Alps and receives considerable amounts of extremely cold weather each year. Despite the harsh climate and relatively short growing season, Holzer has been able to design a farm system that allows him to grow certain types of citrus fruit.
While his neighbors have given up on any sort of agricultural production whatsoever in favor of monoculture forestry systems, Holzer has been able to create a diversified landscape with hundreds of different types of crops. By selectively harvesting the warmth from the sunlight, Holzer is able to grow certain types of citrus trees amongst his apple orchard. While traditional agronomists might tell us that it is impossible to grow apples and citrus fruit in the same region because of the varying climate zones, Holzer has proven them different.
How to Create Microclimates
Microclimates depend on harnessing the elements and concentrating the energy that they bring in a certain area. While there are a number of different elements that can be used in the creation of microclimates, we will focus on three of the most well known and most powerful elements: the sun, the wind, and the water.
The sun is the most powerful source of energy on our planet. Every minute of every day it emits more energy than has been used by the history of humanity. The energy from the sun that reaches the earth brings heat and light which happen to be two of the most needed elements for plant growth.
Creating a microclimate that depends on sun’s energy requires us to find ways to collect the heat and light from the sun in one area. One commonly used and effective strategy is to plant heat traps or sun traps behind one’s home. In the northern hemisphere, the sun falls to the southern sky during winter. To capture the light from the sun requires us to angle our homes towards the sun. Additionally, we can plant a row of trees behind our home (on the northern side). Once these trees grow sufficiently large they will capture the suns light and hold it in the landscape around our home. This will create a much warmer area around our home which not only will allow us to cut down on our energy bills, but also plant certain heat loving crops.
The wind, though constantly shifting, does generally come from one certain direction. Once we have identified the direction from where the wind prevails, we can plant windbreaks (densely planted trees or bushes) to block the wind. The temperature difference where the wind blows and where it doesn´t can approach several degrees Fahrenheit. By planting a few trees or hedges around our land, we might very well be able to lower or increase the overall average temperature.
Lastly, water is another element that can be beneficial in the creation of microclimates. Bodies of water essentially function as thermal masses, or heat traps. Since ponds or lakes are generally dark colored, they will absorb the heat from the sun. This absorption of heat doesn´t only heat the water, but also the surrounding landscape. By placing several ponds around our landscape, we are creating areas of heat absorption and the land around those ponds will be significantly hotter than other areas on our land.
Microclimates for a More Diversified Production
One of the joys of growing your own food or tending your own garden is experimenting with new and different crops. By creating microclimates around your land, you can vastly improve the diversity of crops that will grow in your landscape. As the diversity improves on your land, not only will you enjoy a wider array of crops, but your land should improve in health and resiliency. And who wouldn´t enjoy showing off a fresh lemon grown in an area where everyone told you it was impossible to grow citrus fruit?