Updated: Oct 2, 2021
Permaculture, a Designer's Manual by Bill Mollison describes a microclimate as "[T]he localized climate around landscape features, buildings, and in forests or edges of forests; important for selecting sites for specific crops or species."
In other words, a microclimate is a very small zone within a growing zone, that stays warmer or cooler on average than the surrounding area. This can be due to the amount of sun exposure, wind, or shade as well as other factors.
Essentially, permaculturists have found that it is feasible to grow otherwise impossible crops in a climate not suited for sed crop by planting it in a microclimate!
That's when we as gardeners get to be creative, innovative, and impressive when we show what we have been able to accomplish. Especially at high elevations, this can be the key to growing what others may tell you cannot be grown.
Creating microclimates is in no way a new idea to humankind. In fact, if we time travel to the ancient Andes mountains, we will find a vast empire of agricultural geniuses that had perfected this lost art.
The Tiwanaku culture near Lake Titicaca in Bolivia established what would later be known as Waru Waru agriculture. Practiced heavily by the Aymara descendants, they would essentially create raised beds or free standing terraces between flood zones, creating a much more stable environment for growing massive amounts of crops. The plains area between the raised beds would act as a sun-catch, collecting solar radiation during the day and releasing it at night, in order to keep plants from freezing. Likewise they could allow for some shade during the hottest parts of the year to keep plants from wilting under the harsh high altitude sun. The plains could be flooded or irrigated to increase this effect of temperature stabilization.
This is an example diagram of how the Waru Waru raised field agriculture would operate. Farming land in ancient South America has been estimated to comprise of over 200,000 acres!
Another incredible feat in agricultural science was achieved by another ancient Andean culture on the Peruvian side. Near Cusco, Peru, in the Sacred Valley, is an incredible and astounding set of terraces that has baffled modern scientists for quite some time. This is in reference to, of course, the breathtaking Moray Ruins. Often believed to be a salt mine, this pre-Incan wonder of engineering was actually somewhat of an agricultural laboratory!
On average, the difference between the top and the bottom terraces is about 27°F (15°C). That is quite a remarkable gradient, making perfect habitats for plant varieties innumerable! Not to mention, each terrace would have a slight difference in moisture content, nutrients, wind, and sun as you go round. I like to envision these ruins as an abundantly fruitful food forest! After all, agricultural grounds like these were responsible for feeding tens of millions of people in ancient times.
From these examples, you should have a pretty good idea of how to create your own microclimates. It can be done simply by planting a large shrub or tree to increase shade, planting a garden on a shady side of a building, or using water features like ponds to regulate the nearby temperature. One popular method is fruit tree espaliers like the one in the photo.
On the flip side, you may create a rising spiral of land in order to capture more sun in a cold climate, much like the reverse of the Moray ruins. Build terraces or fences to create wind blocks to save plants from the high speed gusts at high altitudes. Greenhouses and cold frames are another example of creating a microclimate.
Another ancient implementation of microclimate creation is in the Hanging Gardens of Babylon, one of the Old Seven Wonders Of The World. Though physical evidence proving its existence has never been gathered, these magical urban farms were noted by several antiquarian historians. The idea is that multitudes of different plants were able to be grown, even in a heavily populated city due to the creation of favorable conditions in conjunction with fantastic irrigation.
The time is nigh to implement this same type of creative agriculture in the modern world. Doing so would reduce the amount of water needed throughout arid regions, and would even making farming in desert climates much more possible. In our current environmental state, this may sadly be the greater part of the world before we know it!
There is almost no limit to what can be accomplished with some careful observation and proper planning. It is time to begin feeding entire populations from local, organically grown food again. Creating microclimates to increase the variety and cultivation of all crops is an excellent place to start.
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