Garden Microclimates

The temperature range - minimum to maximum range each day, number of days per year near minimum temperature, number of days per year near maximum temperature, and number of frosts are obvious factors that influence plant growth. All these can be altered significantly by the plants and buildings nearby. The temperature will affect plant and root growth rates which will in turn affect water demands of plants, and the amount of evaporation of water from the soil surfaces and plant leaves.

The higher the temperature, the greater the evaporation. Altitude also affects temperature, increasing altitude means cooler temperatures. North facing walls will be warmer than south facing walls, so choose plants that thrive in those conditions.

Both hot and cold winds evaporate moisture from the soil and environment around plants.

Shady trees and screens of plants modify the climate by protecting the garden from heat and strong, hot dry, or cold chilling winds.
A windbreak that acts as a filter rather than a barrier is the most effective in reducing wind.

Years ago wise gardeners discovered the secret of ripening fruit early in a cold place. Fruit trees planted close to a dark coloured wall receive more warmth from the heat radiated off the wall during sunny weather. Heat is absorbed into a flat surface easily, particularly a dark coloured one. When the sun sets, this heat will be given off from the surface for several hours. Paving around a house or dark exposed walls give off heat and can make it uncomfortable to sleep at night. One advantage, however, is that they provide good spots for cacti or succulent plants that like heat.

In winter, dark coloured paving and walls will absorb heat and make the atmosphere around garden beds nearby warmer to improve the plant growth.