Even a small yard or garden has variances in air, light, soil, and water known as microclimates. In my yard, for example, I have:

• One corner that’s dry as a desert, full of angry ants and cracked clay that you can’t break with the sharpest shovel.
• A cool, damp area between a wall and hedge that doesn’t grow much of anything except mosquitoes!
• A northern exposure in the back that stays icy much longer than the southern front of the yard.
• An eastern side where the soil is unusually rich, the air is cool and dry, the sun is gentle, and grass grows faster than I can mow it!

Microclimates are very important to consider when planning your landscape or vegetable garden. Cold and heat tolerance, diseases and pests, and overall plant health can be impacted by even small variations in climate. Some areas of your yard might even be a different hardiness zone than others!

Here are some tips for understanding the microclimates in your yard.

Soil Microclimates

Soil can vary widely in just a small area. If you do soil testing in different areas of your yard, you just might find differences in:

• pH
• Soil texture
• Soil composition
• Nutrients
• Drainage

Water Microclimates

A walk around the yard on a rainy day can reveal a lot about variations in water and moisture. Different areas will be wetter and drier than others, particularly when it comes to:

• Soil drainage
• Humidity
• Grading and runoff
• Shelter from (or exposure to) rain
• Exposure to drying wind or sun
• Location of water table, surface water, and streams
• Competing plants that might hog the available water

Sun and Warmth Microclimates

Different areas of the yard can get significantly different exposures to light and warmth, particularly due to:

• Shade from trees and buildings can reduce light in part of your yard.
• On a sloping lot, higher elevations will be warmer than lower ones.
• The direction your lot is oriented makes a difference, with south-facing yards receiving more intense sunshine than north-facing yards (in the northern hemisphere). Eastern exposures are perfect for plants needing partial sun, while western exposures can be harsh and windy.

Weather Microclimates

All of these factors can work together to create different weather conditions in your yard. Consider:

• Cold Traps: Low-lying areas with poor circulation frequently collect cold air and dampness, particularly if the soil is poorly draining. These areas tend to be the first to frost, so the best way to find them is to note patches of frost on fall and spring mornings.
• Heat Sinks: Pavement, stone, and buildings can absorb heat that radiates to surrounding areas. You may notice drier soil, or spindly plants with heat damage. Plantings around heat sinks need to be heat and drought tolerant.
• Seasonal Variations: Deciduous trees can create sunny areas in winter and shady areas in summer. Northern exposures can be shadier during the winter, and southern exposures can be downright ovens in summer.

Creating Microclimates

Not only does knowledge of microclimates help you work with the conditions you have, but you can also use the concept to create microclimates in your yard that will benefit your design. For example, berms and raised beds can be used to warm the soil and allow for earlier planting, but they need to be monitored during drought.

Windbreaks, shade trees, brick and stonework, and water features all have an impact on the surrounding area and can be incorporated into your garden design not only as decorative features but as a way to grow the plants you want. A proper landscape design will take into account all of these features, in order to ensure healthy, thriving plants and well prepared gardens.

Further Information

• Garden Site Microclimate Evaluation Form (University of California)

Tags: , dry climate, landscape, landscaping