It is important to know your local weather and microclimate in order to select plants that will grow best in your garden. Ideally you should select native plants but plants from a similar climate will also grow well.
Sunshine, temperature, precipitation, humidity, and wind determine your regional climate. Every home landscape has its own microclimate conditions determined by local geology, existing vegetation and manmade structures that either protect or expose our gardens to the elements.
Many resources are available to help you understand your regional climate and plant hardiness in your area. In the western U.S., refer to the Sunset climate zones found in the Sunset Western Garden Book. For other regions of the U.S., the United States Department of Agriculture Plant Hardiness Zone Map, is the common reference.
Another way to determine watering needs is to learn about Evapotranspiration. Evapotranspiration or Et reflects actual climate conditions and is the amount of water that is evaporated from the soil and transpired through the plant’s leaves. This amount of water needs to be replaced through watering. If you know your area’s Et rate, you can plan the amount of water to be replaced through irrigation. Call your local water district or cooperative extension service and ask about your Et rate.