Hardiness Records For Winter 1976-77 And 1977-78
Clarence Hubbuch, Jr., Clermont, Kentucky
According to the U. S. D.A. Hardiness Map, Bernheim Forest Arboretum, in Clermont, Kentucky, is in zone 6b. However, winters 1976-77 and 1977-78 were more like zone 4 winters.
During winter 1976-77 there was a prolonged severe cold period with a low of -23° F. and only a very light covering of snow on the ground. There was as much as 30 inches of ice in the ground under sod.
Winter 1977-78 was similar, with even a longer severe cold period and a low of -23° F. However, there was a 12 to 16 inch covering of ice and snow on the ground the entire winter. There was never over 2 inches of ice in the ground all winter.
The rhododendron are growing on a gentle slope, in slightly raised, prepared beds. They are growing under large Virginia Pines that have been trimmed up to give them plenty of light and some filtered sun. They are protected from winter winds by large Eastern Red Cedars and Virginia Pines.
These rhododendron plantings were started in 1965. They have grown well and up to the winter of 1976 have had outstanding bloom practically every spring. Hopefully this winter will be near normal and we can look for good bloom next spring.
The following is a list of the plants that survived the past two winters as well as those that did not survive.
RHODODENDRON
The following cultivars survived winters 1976-77 and 1977-78. Very scattered bloom spring 1977, practically no bloom spring 1978. Very little new growth the past two summers. 'America', 'Boule De Neige', 'Catawbiense Album', 'Cunningham's White',
R. dauricum
'Artic Pearl', 'King Tut', 'Nova Zembla', 'Professor Amaties', 'Tiffany', 'Vernus'.
The following cultivars were either killed by winter 1976-77 or were so badly damaged that they did not survive winter 1977-78. 'Anna Baldsiefen', 'Anna Hall', 'Betty Hume', 'Blue Peter', 'Bowie', 'Britannia', 'Crimson Glory', 'Mrs. A. T. De La Mare', 'Dora Amaties', 'Dorothy Amaties', 'Mrs. R. S. Holford', 'Ignatius Sargent', 'Michael Waterer', 'Nodding Bells', 'Pink Cherub', 'Pink Cherub', 'Pioneer', R. ungernii, 'Warwick'.
KURUME HYBRIDS
The following cultivars survived winters 1976-77 and 1977-78. Very scattered bloom spring 1977, scattered bloom below snow line spring 1978. 'Blaauw's Pink', 'Coral Bells', 'Glory', 'Hinodegiri', 'Hinomayo', 'Pink Pearl' (some twig damage).
The following cultivar was killed winter 1976-77: 'Snow'.
MISC. RHODODENDRON
The following cultivars survived winters 1976-77 and 1977-78. Very scattered bloom spring 1977, bloom below snowline spring 1978.
'Delaware Valley White'
R. indicum
var.
balsaminiflorum
R. mucronatum
R. mucronatum roseum
R. yedoense
R. yedoense
var.
poukhanense
R. yedoense
var.
poukhanense
'Compacts'
GLENN DALE HYBRIDS.
The following cultivars survived winters 1976-77 and 1977-78. Very scattered bloom spring 1977, no bloom except below snow line spring 1978. No leaf bud or twig damage. 'Cascade', 'Carrara', 'Everest', 'Harbinger', 'Lustre', 'Sambo', 'Martha Hitchcock', 'Merlin', 'Pearl Bradford', 'Polar Sea', 'Sagittarius'.
The following cultivars had no bloom spring 1977 and very scattered to no bloom even below snow line spring 1978. Some leaf bud and twig damage. 'Alight', 'Alight', 'Campfire', 'Content', 'Copperman', 'Corsair', 'Gaiety', 'Glamour', 'Janet Noyes', 'Wildfire', 'Joya', 'Mary Margaret', 'Nativity', 'Picador', 'Progress', 'Swashbuckler', 'Teresa', 'Wanderer'.
The following cultivars are small plants being grown in a very protected lath house. Bloom was scattered both winters but no damage to leaf buds or twigs. It will be spring 1980 before these plants are large enough to plant in the arboretum. 'Aphrodite', 'Coral Sea', 'Coral Sea', 'Fashion', 'Greeting', 'Shimmer', 'Taffeta', 'Vespers'.
The following cultivars were either killed by winter 1976-77 or were so badly damaged that they did not survive winter 1977-78. 'Bagdad', 'Cream Cup', 'Cremona', 'Grace Freeman', 'Helen Fox', 'Lacquer', 'Litany', 'Stampede', 'Tanager'
GABLE HYBRIDS
All plants survived winters 1976-77 and 1977-78. Very little to no bloom spring 1977. Scattered bloom only below snow line spring 1978. 'Boudoir', 'Cameo', 'Carol', 'Corsage', 'Ethelwyn', 'Herbert', 'Jessie Coover', 'Jimmie Coover', 'LaRoche', 'Louis Gable', 'Maryann', 'Old Faithful', 'Robert Lee', 'Rose Greely', 'Rosebud', 'Stewartsoniana'.
GIRARD HYBRIDS
All plants survived winters 1976-77 and 1977-78, with scattered bloom after both winters. The plants listed below are all small plants being grown in a very protected lath house. It will be spring 1980 before they will be large enough to plant in the arboretum. 'Hot Shot', 'Sandra Ann', 'Girard's Red', 'Girard's White', 'Roberta', 'Girard's Late Rose', 'Girard's Rose'.
ROBIN HILL HYBRIDS
All plants survived winters 1976-77 and 1977-78, with scattered to good bloom, after both winters. The plants listed below are all small plants being grown in a very protected lath house. It will be spring 1980 or 1981 before they will be large enough to plant in the arboretum. 'Betty Ann Voss', 'Chanson', 'Dorothy Rees', 'Gillie', 'Gwenda', 'Lady Louise', 'Mrs. Morland', 'Redmond'.
KNAPHILL, SLOCOCK, EXBURY HYBRIDS
All plants survived winters 1976-77 and 1977-78. Some buds were damaged by both winters and did not open the following spring but these were not in sufficient numbers to affect the overall color of the plant when in bloom. 'Aurora', 'Balzac', 'Berryrose', 'Cecile', 'Fireball', 'Fireglow', 'Gibralter', 'Golden Dream', 'Golden Eagle', 'Harvest Moon', 'Hotspur Red', 'Klondyke', 'Knaphill Apricot', 'Mary Claire', 'Mavis', 'Nancy Buchanan', 'Old Gold', 'Persil', 'Pink Balloon', 'Pink Delight', 'Princess Royal', 'Rene', 'Royal Lodge', 'Satan', 'Seville', 'Sylphides', 'Tucan', 'Tunis', 'Whitethroat', 'Wryneck'.
MOLLIS HYBRIDS
All plants survived winters 1976-77 and 1977-78. All flower buds and scattered leaf buds were killed both winters. 'Babeuff', 'Hortulanus H. Witte', 'Lemonora', 'Red Fire', 'Chavalier De Reali', 'Hugo Hardijzer', 'Queen Emma'.
MISC. DECIDUOUS AZALEAS
R. arborescens
- No flower or leaf bud damage from both winters.
R. bakeri
'Camps Red' - Plant dead, possibly from summer heat and humidity rather than winter.
R. canadense
form
albiflorum
- Plant dead, possibly from summer heat and humidity rather than winter.
R. cinnabarinum royali
- Did not survive winter 1976-77.
R. reticulatum
(syn.
decandrum
) - All flower buds killed, plants partially frozen to ground level.
R. nudiflorum
- No flower or leaf bud damage from both winters.
R. vaseyi
- Some flower bud damage both winters.
'Daviesii' (Ghent) - Good bloom both spring 1977 and 1978.