Wherever you live, understanding microclimate is key to successful gardening. Once we learn more about the conditions where we live, in our specific gardens, we can begin to identify the strengths, weaknesses, opportunities, and challenges of the space. We begin to take steps to make things better and to achieve specific goals.
What Is a Microclimate?
Many of us understand the features of the climate where we live. But climate can only tell us some of the information we need to know about the general weather patterns, temperatures, and conditions where we live.
We also need to look at conditions on a much more local scale, thinking about sunlight and shade, wind, water, topography, and more to determine the microclimate conditions in our particular spaces.
The shape of the landscape in our gardens and around them, the existing vegetation in and around our gardens, and the built environment around us, especially in cities, can influence the conditions we experience.
What Do We Mean By a ‘Better’ Microclimate?
When we talk about design in a garden to create a better microclimate, we might be talking about a range of different things.
One common example is that we might be looking to create a garden that remains a little warmer (and calmer, more protected) in the winter months. In cooler climate gardens, we might wish to create a more positive climate for winter growing.
In some areas, however, altering the microclimate to the positive might involve, for example, taking steps to ensure lower temperatures in the height of summer to reduce heat stress in plants.
How to Mitigate Microclimate Challenges
To show some of the approaches that we might adopt to create a better microclimate in our gardens, let’s take as an example the idea of improving the microclimate for winter growing. To keep things warmer and more beneficial for plants over the winter months, we might:
- Design our garden layout with reference to the topography. We might carefully consider the characteristics of slope and terrain, taking advantage of sun-kissed south-facing slopes in the northern hemisphere, and north-facing slopes in the southern hemisphere, for example.
- Look at where frost pockets might form and take steps to alleviate them. On cold nights, cold air forms on cooling objects like trees and flows downhill to collect at low points, or behind barriers like fences or hedges. Making gaps in a barrier can allow the cold air to drain away and alleviate frost pockets.
- Add windbreak hedges and shelter belts of trees and shrubs in order to filter and diffuse the wind and create a more sheltered microclimate on their leeward side.
- Make use of south-facing walls or other structures in the northern hemisphere, since these provide warmer areas for cultivation. Adding thermal mass through structures made of stone, brick, earth, or clay can help us catch and store the heat of the sun during the day, which is then released slowly when temperatures fall at night, keeping temperatures nearby a little higher than they would otherwise be.
- Water also catches and stores the sun’s heat during the day, and so adding a pond or other body of standing water can also create a slightly milder microclimate in the surrounding area.
- Prune larger trees or shrubs to reduce shading that might cause cold areas that are quicker to cool and slower to warm up when temperatures rise.
- Prevent soil from freezing and protect plant roots by adding a thick mulch of carbon-rich material, such as straw or dried leaves.
- Winter wet can often be as much of a challenge as winter cold. So to improve the growing conditions in a particular area, we might also use strategies to manage water wisely and direct it to where it is wanted and away from where it is not. Earthworks, appropriate planting, and improving drainage are all ways to improve microclimate conditions in areas with excessive winter wet. Managing water is also a key priority when creating a better microclimate in summer, especially in areas where rainfall is low during this time.
Of course, we might also introduce covered growing areas like greenhouses or polytunnels within our gardens to create warmer and more protected conditions to grow a range of plants even over the coldest part of the year.
But even when we do so, positioning these and thinking in more general terms about how we might improve the microclimates in our gardens can help us to keep these areas frost-free and achieve the best possible results.
