A-Z of Perennials [antikvár]

The Temperature Zone MapSelecting plants that are adapted to your climate is half the secret of successful gardening. A plant that is well suited to its surroundings will flourish with a minimum of help, while a plant transplanted to an inhospitable site will struggle no matter how much care you give it.Your best tool for identifying such plants is the temperature zone map shown here. Developed by the United States Department of Agriculture (USDA) as an aid to gardeners and nurseries, it divides Canada and the United States, including the Hawaiian Islands, into 11 zones. Most American and Canadian nurseries and mail-order companies have adopted the USDA map as a standard reference.Each zone is based on an average minimum temperature, which is an index of the local winter's severity. In most cases this temperature is the crucial factor in determining whether a plant will survive in a given region. Most plant descriptions in catalogs or on plant labels, for example indicate the zones in which a specific plant will thrive. For instance, the common flowering dogwood will be Hsted as hardy from zones 6 to 9. Once you have identified the zone you are in, buy only plants that are recommended for that zone then you can be reasonably confident that your purchases wdll be adapted to the local climate.However, plant hardiness can also be influenced by certain local conditions. A garden located at the top of a 1,000-ft (300-m) mountain, for example, will usually have temperatures several degrees colder than one in the surrounding plains. And because water collects heat from the sun, a garden that is located on the shore of a pond wdll be both warmer in winter and cooler in summer than a garden just down the road.Such local peculiarities and microclimates may force an adjustment in your use of the temperature zone map. If you have further questions about plant hardiness in your area, contact your local Cooperative Extension or Agricultural Service.