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Climate

Rhododendron species are found in the wild from the arctic regions to the tropics, spanning a wide range of climates.  In the United States, a large number of hybrids and species flourish in the pacific northwest, especially between the Cascades and the Pacific Ocean.  A favorable climate extends down the Pacific coast, the area getting narrower as it goes south, with the San Francisco Bay area being about the southern limit of easy culture for the large-leaved varieties.

Some of the maddenii types grow quite readily in southern California and the tropical Vireyas do well in the Los Angeles basin and along the frost-free coast.  Vireyas also are popular in Hawaii and Florida.

 

R. 'Herklotz'
R. 'Herklotz #5'
Tropical Vireya rhododendron, suitable for
warm climates or greenhouse culture.

Photo by Dick Cavender, Copyright 1996, ARS

Azaleas can be grown on the west coast from British Columbia southward to the Mexican border.  Azaleas grow also in great numbers long the Gulf Coast and throughout the south and southeastern United States, where some of the large leaved rhododendrons are less easily grown.

Hybridization and selection have resulted in new varieties that are adapted to the hotter and colder areas of the United States.  Rhododendrons and azaleas in home and public plantings grow from southern Canada to the southern United States border.  In cold areas where minimum temperatures reach -20 F or lower, only the hardiest varieties will thrive.  Throughout most of the middle west and the great plains area, rhododendrons require care and attention to the varieties planted.  In general, rhododendrons and azaleas have similar cultural requirements with differences mainly in the types which can be grown in the more extreme climates.

Deciduous azaleas, with their colorful blossoms, are popular.  Some deciduous species and hybrids are very cold hardy and some tolerate hot conditions.  At least two species of deciduous azaleas and two species of rhododendrons are native to eastern Canada and several more species are found in New England.  Many species of deciduous azaleas are native to the east, southeast and south and one species grows wild in the west.  Selections can be made from these species and their hybrids which will thrive over large areas of the United States.

  Index of Topics:
  Botanical classifications  |  Use in landscape  |  Plant selection  |  Climate  |
  Protection  |  Soil  |    Planting  |  Subsequent care  |  Fertilizing  |  Pruning  |
  Insect & disease control  |  Propagation  |  Transplanting  |


American Rhododendron Society
Executive Director: P.O. Box 525,  Niagara Falls, NY 14304
Ph: 416-424-1942   Fax: 905-262-1999   E-Mail: lauragrant@arsoffice.org
1998-2014, ARS, All rights reserved.