JARS v55n3 - Tips for Beginners: A Search for Late Blooming Rhododendrons

Tips for Beginners: A Search for Late Blooming Rhododendrons
Sonja Nelson
Mount Vernon, Washington

When the peak of the blooming season has passed, rhododendron flowers need not become a distant memory or solely a deadheading chore. If you are a gardener who feels a post-bloom depression, take heart. Many rhododendrons are late bloomers and extend the season well into summer. The late bloomers are out there and you can find them. This article is intended to get you started on your search for the right late bloomers for your garden.

If you are connected to the Internet, look at the ARS home page (www.rhododendron.org). Webmaster Bob Weissman and the ARS Electronic Media Committee have begun a database of rhododendrons. Each entry is accompanied by several characteristics - including bloom time. The database is now searchable by characteristic, which means you can do a search for late bloomers. You can even do a "multiple parameter" search. This means, for example, you can search for a very late blooming, white hybrid that grows 6 feet in ten years. In case you try this search, the database will come up with one: 'Polar Bear'.

Although the ARS database is still a partial list of available rhododendrons (including azaleas), varieties are being added continually. Late bloomers are designated either late (L) or very late (VL). Here is the list of very late (VL) bloomers:
R. auriculatum
'Elizabeth Ann Seton' (vireya)
Europa Group
R. maximum
'Polar Bear'
R. prunifolium
R. serotinum
R. viscosum

Here is the list of late (L) bloomers:
'Adele's Yellow'
'Albert Close'
R. brachycarpum ssp. brachycarpum
R. brachycarpum ssp. fauriei
'Charles Thorold'
'Dexter's Giant Red'
'Dexter's Spice'
'Dexter's Victoria'
R. eriocarpum
R. farrerae
'Frank Galsworthy'
R. griersonianum
'Hardgrove's Royal Star'
'Mrs T.H. Lowinsky'
a sport* from 'Pearl Bradford'
'Peter Tigerstedt'*
R. semibarbatum
Tally Ho Group
R. tsusiophyllum

Another source for late bloomers is Greer's Guidebook to Available Rhododendrons. In the text, plants are listed as late (L) or very late (VL). The bloom times are based on the Oregon climate, with late as June 1-15 and very late as June 15 through August. Since this list is in a book, a search involves thumbing through the pages or looking at the table, which does not differentiate between late and very late and does not include the species. The species designated as late to very late and very late are listed here:
R. albiflorum
R. amagianum
R. arborescens
R. auriculatum
R. cumberlandense
R. brachyanthum
R. brachycarpum
R. brachysiphon [now maddenii ]
R. bracteatum
R. brevistylum [now heliolepis var. brevistylum ]
R. crassum [now maddenii ]
R. diaprepes [now decorum ssp. diaprepes ]
R. discolor [now fortunei ssp. discolor ]
R. facetum
R. fauriei [now brachycarpum ssp. fauriei ]
R. heliolepis
R. maximum
R. nakaharae
R. nitens [now commonae ]
R. oblongifolium [now viscosum ]
R. pholidotum [now heliolepsis ]
R. ponticum
R. prunifolium
R. semibarbatum
R. serotinum
R. serrulatum
R. thayerianum
R. ungernii
R. viscosum

Here is Greer's list of late to very late and very late blooming hybrids:
'Arthur Osborn'
'Carol Amelia'
Dragon Fly Group
'Edith Pride'
'Edward Dunn'
Firedrake Group
'Good News'
'Great Genes'
'Lackamas Firebrand'
'Lenore' (synonym for 'Lightly Lavender')
'Pearce's American Beauty'
Penelope Group
'Phyllis Ballard'
'Polar Bear'
'Summer Glow'
'Summer Rose'
'Summer Snow'
'Summer Summit'
'Whitney's Late Orange'*

Recent hybridizing has produced a number of late blooming rhododendrons and azaleas. Robert Lee of Independence, Louisiana, has developed a series of fall blooming evergreen azaleas under the trademark name Encore Azalea. These include 'Autumn Embers', 'Autumn Royalty', 'Autumn Coral' and 'Autumn Bravo' (see the Summer 1999 issue of the Journal).

Weston Nurseries in Hopkinton, Massachusetts, has developed a series of summer blooming deciduous azaleas. Among this group are 'Pink and Sweet', 'Weston's Innocence', 'Weston's Nectar'*, 'Ribbon Candy', 'Weston's Sparkler'*, 'Millennium', 'Weston's Popcorn'* and 'Weston's Parade'* (see the Spring 2000 issue of the Journal). Also look at the next article in this issue of the Journal on James Harris's azaleas.

As you can see, the possibilities abound for adding summer and even fall rhododendron bloom into the garden. No need to despair after all.

* Name is not registered.