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Large-Leafed for Full Sun

Posted by gardener365 5a (My Page) on
Tue, Jun 15, 10 at 8:58

I'm only interested in plants or species of evergreen rhododendrons that can tolerate 100% full-sun in Illinois. I'm aware the PJM's are tolerable and I also have quite a few other deciduous azaleas, mostly the Lights Series, doing just fine.
I came across this list yesterday searching for zone 5 rhododendrons (I'm zone 5 even though the Arbor Day has re-zoned me into zone 5b and 6a). Especially tall rhodies but I can be satisfied with the 3-5 footers in relationship to the 8-10 footers.

Here's this link to Estrabrook's Catalogue (all are listed as "typical" Rhododendron info: part sun/wooded area - etc.) I know though that some will grow in full sun, but which I'm not sure. Living in Portland, OR I saw rhodies in the open albeit their climate is not as "demanding hot."
Estabrook's Rhodies

Many thanks,

Follow-Up Postings:

RE: Large-Leafed for Full Sun

Hi Dax,

Some rhododendrons need some shade to keep lacebug down. Those that are reputed to do well in full sun include:

Rhododendron ‘Anah Kruschke’ — (ponticum seedling) 6’, -15oF, ML-L, 3-4/3. A good looking rhododendron that grows well in sunny, hot locations. Its reddish-purple flowers are held in medium sized, tight trusses. Dense and lush foliage with dark green leaves.

Rhododendron ‘Blue Angel’ — (Sappho seedling) 6’, -15°F, M, 4/2. This angel comes from Gene Cockram of Florence, Oregon. It has lovely purple flowers with a contrasting yellow blotch. With strong green, sun tolerant, foliage the growth habit is much like its parent.

Rhododendron ‘Blue Ensign’ — (probably a ponticum hybrid) 4’, -15oF, M, 4/3. Very hardy, sun tolerant, lilac blue with a striking purple blotch. Its truss is similar to ‘Blue Peter’ and while they both become huge plants, ‘Blue Ensign’ is more compact.

Rhododendron ‘Cadis’ — (‘Caroline’ x fortunei ssp. discolor) 5’, -15oF, ML, 3/4. Long, narrow leaves and the fragrant, light pink trusses of this plant genuinely deserve the recognition afforded this cold hardy hybrid from the eastern U.S. A sun tolerant selection.

Rhododendron ‘County of York’ — (‘Catawbiense Album’ x ‘Loderi King George’) 6’, -15oF, M, 3-4/3. Vigorous growing plant with large, upright white trusses of good substance. Here is hardiness, good flower and large foliage, all in one hybrid. Apple-green, somewhat shiny foliage. Sun exposure and cold are well tolerated.

Rododendron ‘Cunningham’s White’ — (caucasicum x ponticum var. album) 4’, -15oF, ML, 2/3. An attractive, compact plant with small, white flowers enhanced by a greenish-yellow blotch. These lovely and numerous flowers open from buds which are flushed with pink. It will tolerate sunny locations but partial shade is best.

Rhododendron ‘Fastuosum Flore Pleno’ — (catawbiense x ponticum) 6’, -15oF, ML, 3/3. Double, lavender-blue flowers with a large golden flare on the upper dorsal lobe give extra interest to this hardy, sun tolerant hybrid. The growth habit is somewhat open but round on this fine plant. Its good foliage is dense and green.

Rhododendron ‘Gomer Waterer’ — (catawbiense hybrid) 6’, -15oF, ML, 3/4-5. This old standby is one of the best whites ever hybridized. Flower buds are a delicate pink that open to blush white blossoms containing a freckling of soft green in the throat. Large deep green leaves make this an outstanding foliage plant. Very sun tolerant.

Rhododendron ‘Trilby’ — (‘Queen Wilhelmina’ x ‘Stanley Davies’) 5’, -15oF, ML, 3/4. Beautiful flowers of deep crimson with black marking. Matte green leaves are set off against red stems to beautify the plant even when not in flower. Sun tolerant.

Rhododendron ‘Wissahickon’ — (parentage unknown) 5’, -15oF, ML, 3-4/3-4. A good choice if you are looking for a vigorous growing variety that is sun tolerant. The bright rose flowers, with a deeper throat, have brownish spotting. A plant of good reputation in the East.

Rhododendron ‘Wyandanch Pink’ — (unknown) 5’, -15oF, M, -/-. This is the rhododendron for that sunny spot in the yard as it does best in the sun. Excellent foliage highlight the vivid pink flowers spotted darker on the upper lobe.

The above descriptions came from the Greer Gardens Website. They are very dependable.

Here is a link that might be useful: Greer Gardens Nursery in Eugene, Oregon

RE: Large-Leafed for Full Sun

  • Posted by bboy USDA 8 Sunset 5 WA (My Page) on
    Wed, Jun 16, 10 at 0:39

You always need the roots of rhododendrons to be in cool soil, regardless of other considerations. That's why they can't grow them in the Deep South, even in shade. And the flowers are apt to melt in hot sun even with a tough variety that is able to grow in the sun. You might be better off choosing another kind of shrub for your most exposed positions. Otherwise, choose specimens with foliage near the ground and plant close together, mulching immediately afterward. You don't want the roots to ever get baked.

RE: Large-Leafed for Full Sun

Printed and stapled. I thank you guys very much. Greer happens to be a favorite nursery of mine as well.

Thank you so much.


RE: Large-Leafed for Full Sun

You've gotten good advice and a great list from rhodyman, but I'd suggest there is at least one other factor to consider. Temperature, especially night temperature is important. Full sun in a coastal area such as the one Estabrooks Nursery primarily serves (or much of Oregon) is quite different from full sun in an area where temperatures can stay in the 90's with 80's at night for days at a time. Large leaf rhododendrons are not really adapted to such hot conditions. Problems with root rots and leaf damage are very hard to avoid.

I don't mean to be totally discouraging, but your success would be much more likely if you could also plant some shade providing trees.

RE: Large-Leafed for Full Sun

Welp, I believe you mainegrower. I've already planted the trees but they're all 1-4' saplings. I've debated this in my mind time and time again and naturally I'm going to fast, and, I know better. I appreciate the information and will use it wisely - from all of you.

Kindest Regards Maine,


RE: Large-Leafed for Full Sun

Dax: Here's another thought or two.

Full sun is also going to mean full winter sun and wind exposure. Temporary barriers such as snow fence and/or burlap are going to be necessary for young rhododendrons.

I'd also advise considering some of the David Leach hybrid rhododendrons, especially those with r. yakusimanum parentage, such as 'Crete". The advantages would be:
a)Z5 -25 hardiness b) Midwest adaptability as Leach developed his plants in Ohio c) thick indumented leaves in the yak hybrids. This gives them added protection for winter winds and makes them highly resistant to lace bug damage.

Some Leach varieties are tougher than others, but the best of them ought to give you a good chance of success.

RE: Large-Leafed for Full Sun

Indian Hawthorns are a great substitute for rhododendrons for sunny spots.

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