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 Rhododendron Sinogrande 
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Joined: Mon May 30, 2016 3:16 am
Posts: 186
Location: Missouri USA
Post Rhododendron Sinogrande
Tim B. - no idea why the big sinogrande died, but wish I did.

The large-leaf plant in the center back of the photo is a Daphniphyllum macropodum - also known as Redneck Rhododendron due to the red petioles.
Supposedly not hardy here and not suited to a windy location, but there it is and I am really pleased with its uniform shape and vigor.
Photo herewith.

Towards the right back of the photo are two dwarf English laurels.

Image


Sun Jul 30, 2017 4:33 am
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Joined: Wed Feb 13, 2013 11:56 pm
Posts: 409
Location: Seekonk, Massachusetts USA, USDA zone 6b
Post Re: Rhododendron Sinogrande
WOW, great to hear you can grow Daphniphyllum in zone 6a! It looks very happy too.


Tue Aug 01, 2017 2:50 am
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Joined: Mon May 30, 2016 3:16 am
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Location: Missouri USA
Post Rhododendron Sinogrande
Tim B. - Thanks. Daphniphyllum macropodum has been an easy grower. Have a smaller one coming along that I obtained from Keeping It Green Nursery. The big one came from Camellia Forest Nursery as a small plant.


Tue Aug 01, 2017 12:30 pm
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Joined: Tue Jun 14, 2011 12:01 pm
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Location: Maryland, USA
Post Re: Rhododendron Sinogrande
David M. wrote:

Rh. sinogrande Falconera/Grandia

Was it really tagged that way? That is curious because those are separate subsections of the genus.

Not to sound like a scold, Anne, but it is a certainty that the Himalayan/SW China bigleafs are going to be incredibly challenging in your climate; with the possible exception of some of most heat tolerant fortunea subsection plants. Like special clones of R. calophytum, perhaps, collected from a hot, low-elevation area...if many even still exist in such locations in China, which is questionable. OTOH, Max X calophytum would probably be fine in your garden, and I'd be happy to send a cutting or two to Van Veen to root for you in the fall; assuming they continue operating. (Kathy, last of the Van Veens - or the Ericaceous ones anyhow - died back in April. But there was a move a foot to keep it in operation, owned by one of the ARS chapters up there. I hope so.)

With all due respect to them...it's entirely disingenuous of RSF to ship those plants to most locations east of the Rockies, heck east of the Cascades and CA Coast Ranges! Unless they know someone owns a gigantic air-conditioned conservatory, or lives on Martha's Vineyard or a few other very choice spots. They know they are dying and they don't give one jot...it's a fundraising system. They do what they have to do; I just wonder if you are fully informed about what you are buying! Nowhere in their catalog does it mention the general impossiblity of cultivating such plants (and for that matter, the various smaller leaved high elevation species) in a typical continental, mainland US climate. Believe me plenty of people tried to grow big leafs on the east coast in the past 100 or so years, just as they tried to grow monkey puzzles. Well, after all that there are 2 mature sized monkey puzzles on the east coast...and zero non-hybridized big leafs!


Sat Aug 05, 2017 9:15 pm
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Joined: Mon May 30, 2016 3:16 am
Posts: 186
Location: Missouri USA
Post Re: Rhododendron Sinogrande
David M. - thank you very much for your much-appreciated commentary and advice. Thank you also for your offer to send a cutting to Van Veen.
I don't intend to sound ungrateful, but I am partial to straight species.
Yes - it is challenging to grow species Rhododendrons here. Much of the literature gives an indication of how hardy they are, but not their heat tolerance.
I keep on trying, and some do better than others. I now add small lava rock to my potting mix to improve drainage. Perhaps my problem is a heavy
hand when watering. This is a technique I need to perfect. It is probably preferable to grow some of the species in the ground, but so many of them
are not winter hardy here. The losses I have incurred this summer are devastating.

The sinogrande was sold as such from two different sources. The four small (1-gallon) ones are doing fine. The larger one is gone.

I have enjoyed reading and rereading your message. Thank you.


Sat Aug 05, 2017 10:20 pm
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Joined: Tue Jun 14, 2011 12:01 pm
Posts: 327
Location: Maryland, USA
Post Re: Rhododendron Sinogrande
"David M."
I'm David T., I was replying to what our moderator David Matzdorf had posted about the way plants were labeled at the Cox nursery in Scotland!

"The losses I have incurred this summer are devastating."

Well, I had a sense of that, which is why I posted a reply even though I've covered some of this material before. I've been collecting plants since I was a preteen and I'm in my 40s now. I certainly know the pain of finding out you just can't grow something but it's a reality some of us, especially in non-maritime climates, have to deal with.

It is a curious and somewhat mystifying reality that sometimes rot-sensitive plants will survive their first year in a pot when they are small, even though they are almost guaranteed to fail later. But I have seen it many times, and not just with rhododendrons. It happened with some of the Eucryphias I've tried, for example. I have various theories of why this can be but no reason to go into them at the moment. The main thing I can offer as an update, compared to my prior posts on this subject, is to say I've had an apparent degree of success with growing slightly-to-moderately rot susceptible plants on mounds. Either of native soil or C-33 coarse builders sand though in the future I'm going to stick exclusively to the latter, which I think is more effective. (and btw I would rank any grandia or falconera subsection species as moderately-to-severely rot susceptible, in a non-maritime climate) You want to partly break up the root/potting soil mass to avoid creating a 'bathtub'. Now I am in a very consistently humid location because I'm near a lot of coastal water...YMMV with such a technique. But surprisingly they don't seem to become distressed by a lack of water as you think they would. Sand, covered in light mulch over a loamy substrate with a high water table...apparently stays pretty moist in typical summer conditions here. The sand has to be higher than what the intact height of the root mass was. I would recommend you at least try this, without of course in any way guaranteeing the outcome will be improved. Adding the correct fungicide certainly might help, too, but most of the heavy hitters against Phytophthora are expensive, labeled for commercial use only and likely to lead to resistance sooner or later. It can't be considered a long term solution but might help the plant get established. The main one I used on a temporary basis is Ridomil.

You are partly correct that over-watering could be part of the picture, but it's really the lack of oxygen that helps the root rot organisms take hold. I think pure coarse sand quickly becomes re-aerated, after rain or watering is over, in a way few other practical rooting substrates can. Some volcanic rocks in a typical potting mix might help too, I can't rule that out but don't have much experience with it. I'd worry the spaces between the pebbles would remain too moist.

But all this having been said, it's possible there's just nothing that you're going to be able to do and the plant will simply not be able to survive your conditions.

I can't help you with the armadilllos...


Sun Aug 06, 2017 12:20 am
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Joined: Mon May 30, 2016 3:16 am
Posts: 186
Location: Missouri USA
Post Rhododendron Sinogrande
On a positive note, the armadillo was shot at 4:35 a.m. on Thursday 8/3/17 with one loud blast from a shotgun. Based on my observations the following two mornings, there has been no further disturbance in my garden. That is a relief.

Thank you for your suggestions on avoiding phytophthora and similar problems.

I suppose I was confused on who was posting the comment I replied to. My apologies.


Sun Aug 06, 2017 1:37 am
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Post Re: Rhododendron Sinogrande
davidmdzn7 wrote:
David M. wrote:

Rh. sinogrande Falconera/Grandia

Was it really tagged that way? That is curious because those are separate subsections of the genus.



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Sun Aug 06, 2017 11:53 am
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Joined: Mon May 30, 2016 3:16 am
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Location: Missouri USA
Post Rhododendron Sinogrande
David M -
None of the sinogrande I purchased had a plant tag.
All were online purchases from growers in Oregon.
The four small sinogrande have a computer generated plant tag with the name only.


Sun Aug 06, 2017 12:13 pm
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Post Re: Rhododendron Sinogrande
Anne Rhody wrote:
David M -
None of the sinogrande I purchased had a plant tag.
All were online purchases from growers in Oregon.
The four small sinogrande have a computer generated plant tag with the name only.


I think there are too many Davids here.

davidmdzn7 is referencing this post about my visit to Glendoick earlier this year.

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Sun Aug 06, 2017 12:17 pm
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Joined: Sun Mar 24, 2013 2:37 pm
Posts: 219
Location: Halifax, NS
Post Re: Rhododendron Sinogrande
Davidmdzn7

Good all round advice.

As for chemical control of Phytophthora I've used Subdue in the past but given its strength & summer application I don't think plants can handle a reapplication of it. I've since refrained from using it as P. was not the problem but rather weevils girdling the stems just below the soil line (in pots that is, I use nematodes now which are quite effective if you buy the correct strain.)

Another important factor in growing these cranky sorts is the summer rainfall. Here summers as a rule are quite dry and especially so when we have a warm summer, this helps immeasurably. When summers are wet the summer is invariably cool. Warm summer rains can be disastrous.

I'm intrigued with your attempts with Eucryphia. Was that E. glutinosa which is reckoned to be the hardiest species? I had one out on my very cool and mild southern NS land and it prospered for a few years but barely grew. Turned out the soil was much heavier than I realized and 10" of rain one November did it in. The Eucryphias, Nothofagus and Embothrium are damnable plants to get going in pots even here where summers are cool; as with any of these cool lovers one miss-timed watering of a potted plant can spell death. Some Nothofagus we can grow if we can get them large enough in pots so they survive the first winter after planting out.

john


Sun Aug 06, 2017 2:29 pm
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Joined: Tue Jun 14, 2011 12:01 pm
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Location: Maryland, USA
Post Re: Rhododendron Sinogrande
John,
Yep, Subdue and Ridomil are the same ingredient, mefenoxam...labeled for different uses I believe, with Ridomil for Greenhouse crops and Subdue for landscape specimens. I just bought Ridomil because it's a little bit cheaper. (still roughly $100 at the time. But that pint will last me many years, you only need 2 cc per gallon or something) There is one other, different class of non-mineral fungicide supposed quite good against Phytophthora, but the price is absolutely punishing, something like $200 a pint. The mineral one I refer to is of course, Aliette, which works but I tend to use very sparingly because I suspect the aluminum part of it could become toxic. Still, that was the first one I used, and I believe it's as effective as mefenoxam, if not a little more so in some cases. In the US the consumer 'Monterey Aliette' was replaced on the market with 'Agri-Fos', which is an acid phosphonate without Al. You can still find Al-Fosetyl, but it's a commercial product now. Finally Kathy Van Veen told me a few years ago that Actinovate, although I believe it isn't labeled for Phythophthora, prevented dieback on lepidotes in her greenhouses, which was an on-going problem with some cultivars like 'PJM'.

Still the above paragraph is kind of a giant moot point, now that I am growing some grafted plants. Whereas fungicide might have kept something like 'Medusa' from outright dying, it still was not very vigorous. OTOH my 'Medusa' grafted onto 'Charles Loomis', is throwing out its 2nd flush of foliage, something the ungrafted plant would NEVER have done in response to the warm, wet weather we've been having. Ungrafted, plants like 'Medusa' or 'Yellow Petticoats' would practically shrink each year in this climate. That being said, I am being very cautious with them, and haven't given them any fertilizer in this their second year. I wanted the graft union to really stabilize, I was afraid if they were fertilized too early the rootstock, which still throws up foliage and probably always will, would be able to callus itself and 'reject' the scion. Now that all of them have a nice round nodule with smooth bark, one seamlessly attached to the other, I will fertilize them next spring and hope to get enough of a flush that I can try some outside. When I got them in late fall of 2015, there was a quite evident line between rootstock and scion, of course. A larger grafted plant I bought from someone local, has already bloomed and budded up for next spring! That variety, an R. forrestii hybrid, would absolutely be dead as a doornail here on its own roots. I am convinced grafting is the best way around intolerance to east coast heat and humidity. OTOH, I'm not going to say it would let you grow a R. rex in Laredo, TX, either!

Thanks for the weevil tip...I have treated my in-ground 'Vulcan' for them, but didn't realize they could go after potted specimens!

So yeah I've tried Eucryphias on and off for years, after seeing them just reaching full bloom in Scotland, late August, as I was leaving there. Back in the mid 1990s. A big one covered in flowers is heart-stopping. 'Nymansey' is the most vigorous in a pot here; but often goes kaput when placed in the ground (what I was warning Anne about) and when it doesn't, it and 'Rostrevor' are probably nowhere near winter hardy enough. Definitely 8a those, if not 8b. E. glutinosa is probably hardier, but sulks and will not grow in summer...probably just too hot and doesn't have hybrid vigor. I've probably tried 3 over the years, 2 'Nymansey', and 1 'Rostrevor'. Seems more root rot sensitive and I don't believe I bothered to treat those with Aliette et al. I actually suspect if you made a cross of 25% an Australian one and 75% E. glutinosa, you might get one that could survive somewhere on the east coast, perhaps periodically dying back like a tender cultivar of Crape Myrtle, but such a cross doesn't exist and never well. They are now in my 'given up, for maritime climates only' list of plants haha.

"Some Nothofagus we can grow if we can get them large enough in pots so they survive the first winter after planting out. "

HOWEVER after admiring lovely southern beeches in the Antipodes, I'm not quite so quick to give up on those yet. So it's interesting you mentioned them. I'm thinking of ordering some seeds of a couple of the species and just sowing them in a varmint-protection cage somewhere in the garden, semi-shaded spot, and see if natural selection will find a tougher one. The fellow who owned Arrowhead Alpines and is now deceased was prone to outlandish plant descriptions in his sprawling catalog, once stated that there had been an entire grove of southern beeches in a park in a Detroit suburb. Right along the water so maybe even 6b. But was later cut down for some reason. Taken at face value it implies at last some of them (I think he said that was N. antarctica) have a fair amount of hardiness.


Last edited by davidmdzn7 on Sun Aug 06, 2017 3:48 pm, edited 2 times in total.



Sun Aug 06, 2017 3:15 pm
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Joined: Mon May 30, 2016 3:16 am
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Location: Missouri USA
Post Rhododendron Sinogrande
Thanks for recalling memories of Arrowhead Alpines' catalog. Quite a read.


Sun Aug 06, 2017 3:42 pm
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Joined: Sun Mar 24, 2013 2:37 pm
Posts: 219
Location: Halifax, NS
Post Re: Rhododendron Sinogrande
DavidMDZN7

Thanks for the tips, especially actinovate and lepidotes. I should have mentioned Kathy's ghouses likely heated up too much for lepdotes, the RSF has a dynamite cooling system in their prop house and their lepidotes were superb.

And I should have mentioned that here E. glutinosa was also seasonally-confused, in the ground it flushed in very early autumn and my last batch of seedling in pots flushed inmid to late February and promptly collapsed and died in April in the ghouse. I'd not consider hybridizing w. Eg until it has proven itself hardy here - you braver than !

Panayoti Kelaides of the Denver BG was here a few years ago and said coastal Nova Scotia and easternmost Newfoundland were the only places he ever saw as Nothofagus sp. alive east of the rockies. Tip - N. antarctica likes cold soil that's damp, N. procera & obliqua good drainage and N. pumilio sharp drainage and dryish. Propagator at The Arnold said he had neither seen nor could find no references of N. in any eastern BG. Seeds need to be fresh which means buying them in SAmerica in mid to late Spring in our hemisphaere (their autumn).

john
20c / 98% humidity


Sun Aug 06, 2017 6:56 pm
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Joined: Tue Jun 14, 2011 12:01 pm
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Location: Maryland, USA
Post Re: Rhododendron Sinogrande
John,
Cool, thanks for the tips. Sheffield Seed has some seeds now, that they list as fresh crop. Was actually going to try N. alpina and N. obliqua. With the assumption most of them will die in our hot weather but one or two out of 50 might make it. IIRC, years ago the owner of a defunct nursery called "Weird Dude's plant zoo" told me that's how he had found a heat tolerant phormium, just by planting a bunch of seeds. If it doesn't work, it doesn't work. No harm in trying.
(And actually if one thinks about Cordyline australis being used as annual bedding plants all the way down to the mid or upper south, they probably went through a re-selection process for heat tolerance. No doubt the average, random seed you picked from somewhere in NZ would not tolerate our summers. Or perhaps it just so happened that the original seeds grown in California, came from the warmest parts of NZ like Auckland...apparently there are many ecotypes of that species throughout the country. Though obviously even those are not heat tolerant enough for the places they'd survive the winters, which would basically be florida and the gulf coast. After the mild winter of 97-98 and following growing season, ones at shopping centers in the DC area were getting 4' high and started to trunk!)


Mon Aug 07, 2017 3:11 pm
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