Microclimates can be a farmer’s or gardener’s best friend. A few years ago, I wrote about how use of microclimates, or pockets of a garden that have varying temperatures and exposures to weather elements, can expand your choice of xeric plants.
The easiest example of a microclimate is a greenhouse. Windows let sun in and walls, a roof and other strategies help maintain the warmth. Add a heating source (and enough space) and you can grow nearly any plant any time of year.
Subtle microclimates exist all around your yard and gardens. Structures and hardscaping absorb heat during warm hours and release it gradually, helping to protect plants from cold; they also can protect plants from wind. Partial shade shields plants from heat, and slopes or other topography alter how the overall climate affects a given plant.
The Zinnia Experiment
I would like to say that we planted zinnia seeds in three different places simply to later show how microclimates affected their growth and hardiness. But I’d be pushing the truth. I did plant them in several different spots to see how well they grow here and how quickly they bloom, so I can use them as an easy annual filler to add color and even more pollinators to our gardens.
So, we put seeds in open space in our vegetable farm rows, mostly for the pollinators. We also planted some on a fairly exposed raised bed in our xeric garden. Finally, we planted seeds in the lower part of the xeric garden, close to the rock wall. All of the flowers did fairly well, although the ones in the farm area had better soil and more consistent drip watering. They were the tallest and healthiest. The ones in the raised bed took longer to come up, likely because of poorer soil and an inconvenient hand-watering location. The flowers planted in the lower bed did almost as well as the ones in the farm area.
Then the frost came and the healthiest plants burned the worst. They more or less bit it overnight.
The zinnias in the raised bed were nearly as bad, but at least the flowers kept their color (I planned to take photos of them, but hard-working hubby cleaned up the bed before I had a chance.)
The zinnias in the lower bed fared the best. I doubt they will grow or flower more, but they don’t look like they belong in a horror movie.
How to Use Microclimates
The experiment helped me get a sense of microclimates on our land. We’ve always assumed that our farming area is cooler because it is in a sort of mini-valley jut above the river. The dead zinnias demonstrated we were right, especially since those plants were the most robust before the freeze hit. The flowers in the raised bed are more open to cool air; there were no other plants nearby or much hardscape to absorb heat either.
The hardiness of the zinnias in a more protected and “solarized” spot near the rocks was telling. It’s always important to think about sun and shade exposure, but sometimes we fail to consider how placing a few large rocks behind a cold-sensitive plant can help it survive winter. In vegetable gardening, for example, using fabric to cover plants creates a micro-greenhouse effect. And when growing a plant that needs a little less sun or heat, shade cloth or plant placement can lengthen growing seasons.
Microclimates, like the general climate, can vary. For example, a tree that drops its leaves provides no shade until it fills in late spring. As trees mature, they can begin shading a plant that once received full sun; it might be time to transplant a shaded shrub. Windbreaks help slow the flow of cold air streaming up a slope.
Containers offer excellent microclimates, not only because they warm up quickly, but because you can move them to solve sun and wind exposure issues, and all the way inside before the first frost.