Have you ever walked along a country road and looked closely at the vegetation growing alongside? Most every country road I’ve known has distinct lines of differing vegetation between the road and the ditch and then another type of vegetation across the ditch. My road has a strip of about four inches of plantain in the gravel next to the black top. Next is a narrow ribbon of a weird grass that looks like some kind of fiber optic wire called common spike rush. After that is a mixture of violets, yarrow, purple vetch, hemp dogbane and reed canary grass. On the other side of the ditch is more reed canary grass and once in a while a few stalks of asparagus.
The reason for these strips of varying vegetation is that each prefers different environments, and conditions change rapidly roadside. Nearest the road the temperature is warmer and the soil is sandy and gravelly. Moving away from the road, the soil changes to clay and the angle of the ditch becomes steeper, so the plants get more or less sun depending on the time of day and more or less water as rain runs off the road.
These differing conditions are called microclimates, which is defined as “the climate of a very small or restricted area, especially when this differs from the climate of the surrounding area.”
Every landscape has its own microclimates. It takes time to observe and become familiar with your own yard’s microclimates or to create them where they don’t currently exist.
Generally, the south side of a house or other structure is where to locate plants that need more sun or protection from the wind. The north side is where the shade-lovers go. North and west-side plants need to be able to withstand more wind than those on the east and south.
An example of one of the tiniest microclimates is the south side of a large tree trunk. It’s common to see the very first trillium blooms snuggled up to the south-side base of an ash or hickory while nearby trilliums barely show flower buds.
You’ve probably heard the weatherman say, “cooler near the lake” in reference to Lake Michigan. This is also true of smaller water bodies in the summer months. Conversely, it is warmer near the water in spring and fall so the first and last frost might not happen the same as it does just a hundred yards away. Near water, you may be able to plant out earlier in spring or not have to cover plants in fall while your neighbors nearby are scrambling to protect tender plants.
A rock pile, cement foundation or large expanse of concrete driveway will absorb heat from the sun during the day and keep nearby plants warmer through the night. This might allow you to set out annual plants earlier, or even to grow a perennial plant that might be recommended for a colder USDA Hardiness Zone than Winnebago County’s Zone 5a.