Love this one, but I'm not growing it -

Rhododendron Species Foundation, Federal Way
www.rhodygarden.org (plant sale end of next month)

Greer Gardens also offers it - Eugene OR and they ship, reliable source

Here is a link that might be useful: Greer Gardens

Sorry Tom, I can't help you locate one, but I do share your interest in them. For everyone who doesn't know this incredible species, here's a link.

Here is a link that might be useful: R. sinogrande

Not very hardy, you will need to be in a banana belt area to keep it going long term. Too rare for cutting exchange likely, plus there aren't many suitable small terminals. Huge leaves adaptation to excess summer rainfall and gloomniness of wild habitat. Best plant I've seen was in shady blufftop woodland just east and south of Hood Canal bridge. Lots of sword fern and grand fir, both indicating moist, fertile soil. Similar environment to David Lam Asian Garden at UBCBG, Vancouver, BC, but more dense--the plants were basically inserted into existing forest, without much clearing evident. They had a variety of Falconera and Grandia rhododendrons, most still young. The Rhododendron sinogrande had leaves nearly, if not fully 3 feet long.

Well I have a nice protected spot I think may work. The Fatsia Japonicas thrive there & look great even through the coldest winters, & I'm guessing their min. temps will be similar.

How about seed? Does anyone know of a retail source or have any seed to trade?
Thanks for all the info! : )

- Tom

Tom, you can buy sinogrande seed as well as the plants from the Rhododendron Species Foundation

rhodygarden.org

Thanks for that link! I'll have to give them a try.

How about any seed germinating tips? Is freshness a large factor with rhododendron seed? Stratification? Bottom heat? Many thanks again.

No stratification required.

Why don't you read through steps 12, 13, 14 by Dr Goheen, he certainly describes the process as simply as anyone.

If you don't have an adequate light set up, by the time you get seeds, then have seedlings...outdoors in a semi protected spot with morning sun or dappled sun will work just fine for your seedlings.

(the tropicals have short viability seed, I don't think very fresh seed is as important with most varieties we would grow)

Here is a link that might be useful: Goheen - From Seed

I live in coastal Southeast Virginia on the border of 7/8. I can protect during the winter, but could sinogrande or any other bir leafed rhododendron handle an occasional 100+ F day?

If you don't see other rhododendrons all over the place you may be too far south. Main problem hot, wet root environment being just too good for root rot. Some azaleas can grow anyway, that's why you see certain types of evergreen azaleas but not other evergreen rhododendrons in parts of Deep South. Look for a local rhododendron society chapter, that is where you will meet the enthusiasts who are pushing the envelope.

Jeff,
my guess is no, not going to grow in Southeastern VA. Remember too when you have a cold winter like 94 - 0F in Williamsburg, Virginia - that will be way too cold for these Himalayan Rhodies. Neriums, palms, green phormiums, and 25' Eucalyptuses at the defunct Wallace garden were killed or killed to the ground that winter.
HOWEVER, the fortunei series are some of the most tolerant to the southeastern climate. Rhododendron calophytum has some of the biggest leaves in that group. I believe there might be some Rhododendron hybrids at the Norfolk Botanic Garden, if you haven't been there, give it a visit. I bet they have some with R. fortunei parentage, and possibly the species itself. You can get R. calophytum from various outfits including the RSF.

As for protecting them...remember they get huge eventually, like a southern magnolia. I guess you could for the first few winters but I think it would not be worth the effort. They would probably be more sensitive to efforts to protect them than most other plants.
Years and years ago on the net - 98? - I read an account of someone trying to breed a hardy big leaf in NJ. It might have been Hank Schannen - he's certainly a reasonable candidate but it might have been someone else. Maybe rarefind will introduce one someday.
In ROTW by Leach or possibly another old-time Rhodie book, it is mentioned that the garden in SE PA where the Dexter hybrids were bred maintained an outdoor Rhododendron rex or R. fictolateum for a number of years.

Greer, Guidebook to Available Rhododendrons gives these minimum temperatures:

R. calophytum var. calophytum: -15F
R. rex ssp. fictolacteum: -5F
R. rex ssp. rex: 5F
R. sinogrande: 10F

"I read an account of someone trying to breed a hardy big leaf in NJ. It might have been Hank Schannen - he's certainly a reasonable candidate but it might have been someone else. Maybe rarefind will introduce one someday."

While this thread hasn't died, I'll say for posterity this proved to be Frank Furman of New Jesey and his "Sky" series with mostly R. macabeanum as a 50% parent. The balance was mostly the grex called "Catfortcampy". Rarefind sometimes sells various Sky series. They are some of the most beautiful hybrids that can be grown on the East Coast. The leaves are not huge, but big by Eastern standards, and the flowers and large and gorgeously colored. They are probably a little trickier than an ironclad, so, don't order one unless you have good experience with easier rhododendrons.

There are also three calophytum hybrids I'm aware of which reportedly are growable in the East. 'Babylon' which is usually available from Rarefind and two that were developed at the University of Connecticut, 'Buzzer Beater' and 'Tip Off'. The latter looks especially good in the few pictures I've seen.

I would expect all of them to need quite a few years before blooming and to be quite sensitive to root rot problems in hot summer climates with high overnight temperatures. Even though calophytum itself is rated to minus 15, I don't think it's adaptable to the hot eastern climate except in coastal areas with more moderate highs. The only sizable one I've ever seen was in Nova Scotia.

'Babylon' is growing just find for me, it hasn't bloomed yet though. I did see a blooming plant at Rarefind; the ghastly sweet yet murine floral odor is unique. Nice looking flower though. I have a couple other hybrids involving R calophytum and don't think they are really a problem anywhere north of DC if you follow correct cultural practices. (in summer anyhow...obviously they aren't going to make it on top of Mt. Washington) Yellows involving R. wardii, of course, are another story entirely.

davidrt28: What are the other calophytum hybrids? I would also be very interested in reading about what you see as the best cultural practices. In Rhododendrons of the World, David Leach says species calophytum is not hardy north of Philadelphia. This certainly does not square with the -15 rating.

I have had this Sino-Grande x Falconeri for a couple of years. It was purchased at the Rhododendron Species Foundation in Federal Way, Wa. I brought it into an unheated sun room for the coldest parts of last winter, not trusting it well enough to withstand our worst weather in terms of cold. Sooner or later I will have to plant it out in a suitable location. In my colder than normal Zone 8 garden in the Cascade foothills, it's gonna be a stretch. I've seen single digit temps several times over the years. Maybe global warming will come to the rescue!
Mike
{{gwi:384667}}

Nearly all the Grandia and Falconera were burnt last winter at the Rhododendron Botanical Garden. They do have a lot of them down in or near a hole, which makes me wonder if they are getting more cold than the upper garden - and other sites in the vicinity. Out your way I would bother with only the most hardy ones, like fictolacteum.

it got down to about 10 degrees F. there last year. That shows what kind of plants we are talking about (Grandia and Falconera are botanical sections, in case anyone thought I was talking about just the two species R. grande and R. falconeri). At around 10 most of them start to fail, in some instances damage starts as much as several degrees above 10 - showing these are not really cold climate plants at all. The old, tree-sized specimens in Britain that sometimes date back to original collections made during the 19th century are on the west coast, where it is Californian mild.