The US and Canada are divided into climactic zones, ranging from the coldest at Zone 1 to the warmest at Zone 11. The rating system is based primarily on a region's average annual minimum temperature. Variances within a zone occur and are called microclimates. For example: your region is in Zone 7, but your yard is on the north side of a large hill; there, the local microclimate might be more accurately described as a Zone 6.
U.S. Department of Agriculture classifications according to annual minimum temperatures and/or lengths of growing seasons. Also referred to as USDA zone.
a guide reference for nurseries and gardeners to determine if a plant can grow in their local area
Established by the U.S. Department of Agriculture. The United States and Canada comprise 11 zones, based on average to low temperatures in winter. The hardiness of a plant is the range of zones in which it will grow most successfully (usually listed on plant labels).
sections of the country designated by expected range of low temperature.
Zone de robustesse Beständigkeitszonen, pl. Resistencia a las heladas Refers to the state of the climate in a specific region. It gives an indication of the average of minimum temperatures reached over the year. See map.
A plant can be expected to grow in the zone's temperature extremes, as determined by the lowest annual temperature. Other conditions such as moisture, soil, and wind might affect the availability of individual plants. .
A region where the coldest temperature in an average winter falls within a certain range, such as between 0 and -10 degrees Farenheit.
A geographic area that contains a set range of average minimum winter temperatures. From the USDA map, southern Ohio is generally zone 6 (range of 0 to -10 degrees Fahrenheit minimum temperature in a given year), and northern Ohio is generally zone 5 (range of -10 to -20 degrees Fahrenheit minimum temperature in a given year). A given plant is at the northern limit of its range when it encounters its winter hardiness zone temperature. In recent years, winters have generally been much warmer than average.
A hardiness zone is a geographically-defined zone in which a specific category of plant life is capable of growing, as defined by temperature hardiness, or ability to withstand the minimum temperatures of the zone. The zones were first developed by the United States Department of Agriculture (USDA), and have subsequently been adopted elsewhere. They are categorized according to the mean of the lowest temperature recorded each winter, termed the "average annual minimum temperature".
