See  Rhododendron for information on this genus

 

In the descriptions of the Rhododendron hybrids and species below, the follow information is given:

  • Approximate height at 10 years
  • Hardiness temperature (°F), the minimum temperature a mature plant can take without serious injury
    • The minimum temperatures for the following USDA Zone hardiness are:
          USDA Zone 4     -20° to -30
          USDA Zone 5     -10° to -20
          USDA Zone 6     0° to -10°
          USDA Zone 7     10° to 0°
          USDA Zone 8     20° to 10°
    • In some catalogs rhododendrons are given a "hardiness ratings" as H-1, H-2, H-3, etc.   These "H" values correspond to minimum hardiness temperatures as follows:
      •     H-1      to - 25° mid-point of USDA Zone 4
            H-2      to - 15°F, mid-point of USDA Zone 5
            H-3      to - 5°F, mid-point of USDA Zone 6
            H-4      to 5°F, mid-point of USDA Zone 7
  • Flowering season
    • The flowering seasons in Oregon is as follows (from Greer's, 1996):

      •     very early

        		     Jan., Feb., to March 15
            early     March 15 to April 15
            early-mid     April 15 to May 1
            mid     May 1 to June 1
            late     June 1 to June 15
            very late     June 15 through August
  • Quality rating
    • The numerical quality rating (e.g., 3/5/4) is based on a 1 (poorest) to 5 (best) scale for the following attributes (and in the order given):
    • flower / foliage & plant / performance. The rating is by the American Rhododendron Society.

 

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