I’ve had a thing for Rhododendrons for quite some time. What’s not to like? Dark evergreen leaves on a dense, nicely formed shrub that will add interest year round to your gardens. Top that off with spectacular, showy trusses of flowers in the spring and you have the ideal shrub. Here in Vermont however, I find myself on the borderland of where these captivating plants can be successfully grown. But maybe frontier is a better description - a place where limits are tested and new ideas in plant breeding reveal possibility. The old standard, in every garden center, hardy Rhododendron - typified by Rhododendron ‘Roseum Elegans’ with its mauve colored flowers - were about the only “Rhody” you would see in landscapes north of Massachusetts. But starting in the mid 1980’s, I began a quest to learn about what other options existed in the serious Rhododendron collector’s world. I soon found there were several dedicated enthusiasts who were working, sometimes for their entire careers, at developing new forms that are adaptable to more northern climes. The photos below of some of these varieties planted in our garden over the last nearly 40 years will give one a sense of the possibilities.
A sampler of Rhododendron flowers from the exceptional 2021 season. With a minimum winter low of only -10F, and an abundant bud set in 2020, almost all the cultivars in the LHBG collection bloomed profusely .
ELEPIDOTE or Large-leaf Rhododendron
The classic large-leaf, evergreen rhododendron group.
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Rhododendron 'Catawbiense Album'
Rhododendron 'Dexter's Purple' - Hardy to -18F
Rhododendron 'Big Deal' - Hardy to about -15F Developed by Ed Mezitt at Weston Nursery, Hopkinton,MA
Rhododendron bureavii - Rarely blooms here but grown for its fabulous dark foliage and rusty indumentum on the lower leaf surface. Native Yunnan, China at 11,000-13,000 ft.
Rhododendron 'Hoopla' - A UConn introduction hardy to about -18F
Rhododendron 'White Dimples'
Rhododendron 'Edmund Amateis' - one of the best performers for zone 4
Rhododendron x - An un-named hybrid of 'County of York' x Catalgla from Wynterset Nursery in western PA. Another reliable bloomer for zone 4
Rhododendron 'Connecticut Yankee'
Rhododendron 'Luxor' - A Leach hybrid
Rhododendron 'Golden Gala' - David Leach's early attempt at a hardy yellow
Rhododendron smirnowii - A rare species native to the Caucasus Mt.; Gray indumentum on the underside of the leaves.
Rhododendron 'Besse Howells'
Rhododendron 'Ice Crystals' a hardy western PA. hybrid by Robert Blough, Winterset Nursery
Rhododendron 'Nova Zembla' - an old cultivar that is fairly red and hardy to about -18F
Rhododendron 'President Lincoln' - a very old cultivar that is reliably hardy in zone 4
Rhododendron 'Rio' - front Another unique flower color from the extensive career of hybridizer David Leach
Rhododendron 'Great Eastern' - Dexter hybrid
Rhododendron 'Wyandanch Pink'
Rhododendron 'Judith Ann'
Rhododendron 'Peter Tigerstedt' - Hardy hybrid from Finland for zone 4 gardens
Rhododendron 'Tapestry' - Weston Nurseries hardiest purple
Rhododendron 'Slippery Rock' - Later blooming hybrid from Winterset Nursery
Rhododendron yakushimanum 'Ken Janeck' - Flowers are a deeper color as they first open
Rhododendron yakushimanum 'Ken Janeck' Close up of flowers in early stages of opening. The underside of the leaves have a thick brownish indumentum for added interest.
Rhododendron yakushimanum 'Ken Janeck' -Flowers fade to almost white as they mature. Native to the volcanic Yakushima Island, Japan
Rhododendron yakushimanum 'Ken Janeck' - as flowers fade they loose their pink pigment .
Rhododendron 'Bali' - A Leach hybrid with tropical looking flowers. Hardy only to about -15F
Rhododendron 'Ingrid Mehlquist' - Early blooming in mid May. Excellent compact plant Developed by Geneticist Gustav Melquist at the Univ. of CT, Storrs
Rhododendron 'Ingrid Mehlquist' - Flowers become white as they age
Rhododendron 'Anna Hall' - Pink buds fade to white. An early Leach Hybrid
Rhododendron 'Gosh Darn' - very pale yellow hardy only to about -15F
Rhododendron 'Calsap' - A reliable bloomer here, this cultivar is an enticing addition to the group of hardy zone 4 plants, presenting an eye catching maroon blotch on the dorsal petal.
Rhododendron 'Henry's Red' - An exceptionally deep red color for a very hardy red Rhododendron. Difficult to find sources to acquire this cultivar.
Rhododendron 'Boule De Neige' - compact growing. This plant is 45 years old and still under 6' tall. Hardy to -15F
Rhododendron 'Hoopla' - close up of flower. A hybrid developed at UCON in Storrs, CT
Unknown Hybrid - lost the label!
Rhododendron 'Bali' -
Rhododendron 'Casanova' - my favorite cultivar in the collection. Amazing transition from deep pink bud to a pale peachy pink. Reliable bloomer with abundant bud set every year. A David Leach hybrid he developed to provide pollen (hence the name!) for his long term project to develop a truly hardy yellow Rhododendron.
Rhododendron 'Casanove '- close up of flower
Rhododendron maximum - "Rosebay" or "Great Laurel" Native to Vermont, this species is found in just a couple locations here in Vermont. A large growing ,late blooming species, it can brighten a shady woodland site with its light ping flowers. Perfectly hardy in zone 4, it is in flower here typically around the 15th to 20th of July.
Rhododendron maximum - Great laurel or Rosebay. Can reach over 10' tall in VT.
LEPIDOTE or Small-leaf Rhododendron
These rhododendron are primarily early spring bloomers with smaller leaves and flowers, and can be fully evergreen to deciduous with some nice fall color.
Rhododendron mucronulatum 'Cornell Pink' - 'Cornell Pink Korean Rhododendron" Fully deciduous, plant has excellent yellow fall color
Rhododendron mucronulatum 'Cornell Pink' - flowers are brighter pink when first open
Rhododendron mucronulatum ' Cornell Pink' - close up of flower
Rhododendron mucronulatum var. taquetii - dwarf form of Korean Rhododendron found on Jeju Island, Korea
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Rhododendron 'Balta' - Pale pink buds eventually turn white on this zone 4 plant from Weston Nursery's cold hardy breeding efforts. Partially evergreen.
Rhododendron 'Olga Mezitt' - reliably hardy flowers for zone 4 from Weston Nursery. Bronze green winter foliage.
Rhododendron 'Brittany' - a very full, compact plant with unusual bell shaped flowersSmaller evergreen Leaves
Rhododendron 'Milestone' - another Weston nursery introduction blooming in early spring
Rhododendron 'Balta' - early stages of flowering
Rhododendron 'April Snow' - Pure white double flowers in early spring
Rhododendron 'Llenroc' - an excellent zone 4 reliable plant with nice late fall color