HARDY AZALEAS AND RHODODENDRONS

HYBRID AZALEA SHRUB 'GOLDEN LIGHTS'...

...FLOWER BRACT

PJM RHODODENDRON, JUNEBERRY AND FORSYTHIA

Sunday, 8:15 AM.  72 degrees F at the ferry dock, 65 on the back porch.  Wind SW, light with stronger gusts.  The sky is clear except for a band of wispy white clouds blowing in on the SW wind.  The humidity has dropped to 61% after a stormy evening that left almost a half inch of rain in the gauge.  The barometer is steady for now, at 29.81".  It looks like a somewhat unsettled week ahead weather wise.

   There are a number of cold hardy species, varieties and hybrids of rhododendrons and azaleas.  Both rhododendrons and azaleas are members of the genus Rhododendron, the main difference is that the former are are evergreen, retaining their leaves in the winter, and the latter are deciduous.  Wisconsin has only one native species of Rhododendron, and that a very rare relict of glaciation that grows in small, isolated populations north of Madison in the Dells of the Wisconsin River. and on the cliffs of the Kickapoo River.  R. lapponicum, the Lapland rhododendron, is a disjunct, far out of its native range a thousand miles north.

   The University of Minnesota has introduced cold hardy azalea hybrids, the Northern Lights series, that can withstand northern Wisconsin winters, but as do all Rhododendrons they require an acid soil and some care in location and planting. Being near the insulating waters of Lake Superior is of course helpful.  A few other species and hybrids are also hardy, including PJM, a selection of the Korean rhododendron. There are also some hardy introductions from Canada and Finland.
   I have a protected location where I am growing some of the Northern Lights hybrids and other Rhododendrons. Both 'Golden Lights' and 'Rosy Lights' have established well and bloomed every spring, but this year 'Rosy Lights' had not a flower, whereas 'Golden Lights' has been very floriferous.  I am mystified, but that is half the fun of the game.  I will try fertilizing with an acid based fertilizer.

   For more information on hardy Rhododendron, see Azaleas and Rhododendrons for Minnesota, by Michael Zins, University of Minnesota Extension.