Rheum nobile/alexandrae

[Philippe]

Hi

Has anyone already tried to grow the nobile?
I planted some seedlings of it a few days ago. They won't have been frightened by the weather in the meantime: fog, clouds, and permanent drizzle are on the program since then

I was wondering if the nobile was rarely ( if never?) seen in the weather-favoured gardens ( private or botanical) because of its relatively new introduction ( am I right?) or simply because even in those blessed gardens its culture was still very difficult.

Rheum alexandrae grows without any problem by me, even in purest peat and without any care, but anyway it might be of easier culture then.
But would the superficial likeness be a little clue to any growth/climate requirements similarities with nobile, or not at all?

I spent so much time on preparing place and soil for the nobile! I dare not to say how long it took me before I could finally plant the "magic" seedlings in what I think to be the best place/soil...For the moment!

[Susan]

I have grown a number of rheums and appear to have success with them, however, Rheum nobile, I believe needs very sharp drainage.  If you look at the habitat it comes from, it appears to be rocky slopes in moist conditions.  Of the 3 people here in Dunedin,  that had a plant each, we all lost them.  We realised that keeping it moist is essential but not "wet", as they all rotted off. 

There is a fabulous photo on the front of an AGS Bulletin from some years ago (about the seed collecting trip to Sikkim, if I recall) and it is not in a bog but on a very rocky and quite steep looking  slope

Good luck with it, would love to get seed again so I could give it  a go in a more appropriate place.

Susan

[Lesley Cox]

I had 3 from seed and they all rotted off over three years. It almost looks like a scree plant.

[Philippe]

Thank you for your answers Susan/Lesley.
I added grit to the soil for the drainage, but my first guess, having already seen pictures of its environment, was that I didn't really know how to imitate the natural conditions in which it grows: somehow I can't "imagine" such a giant plant thriving in the scree environment, although it is of course. Such big leaves, such a stout root, such a height! It's so easier to think of smaller and creeping plants in those conditions...
I still have a few other seedlings who will overwinter in pots with well-drained medium, and 2 directly in the propagation bed ( where the earth is not really of scree-nature, but generally still "alpines-friendly" for a short stay of 1/2 seasons).
Let's see who will do the best amongst these three "groups".
I pray they're not all dead when I come back next spring...That would make me enrage 

[Philippe]

Perhaps a silly question...but could be generally said that if plants generally requiring faultless drainage ( for example the north american lewisias) thrive well in the open air without any protection against winter or summer wet, it would mean that the soil itself, at least, could also satisfy a rheum nobile regarding to the precise and only aspect of drainage??? (beware, I don't take consideration of the atmospheric conditions or other still ununderstood needs in the particular case of the nobile)

I have grown a number of rheums and appear to have success with them, however, Rheum nobile, I believe needs very sharp drainage.  If you look at the habitat it comes from, it appears to be rocky slopes in moist conditions.  Of the 3 people here in Dunedin,  that had a plant each, we all lost them.  We realised that keeping it moist is essential but not "wet", as they all rotted off.  

There is a fabulous photo on the front of an AGS Bulletin from some years ago (about the seed collecting trip to Sikkim, if I recall) and it is not in a bog but on a very rocky and quite steep looking  slope

Good luck with it, would love to get seed again so I could give it  a go in a more appropriate place.

Susan

[Lesley Cox]

If I understand your question correctly Philippe, then the logical answer would be "Yes" but as you recognise, there are many other factors involved. Without knowing why, we all lose plants beside perfectly healthy and strong plants, yet they should require exactly the same conditions of soil, drainage etc. It's a shame with Rheum nobile, that there's virtually no material available with which to experiment.

[Philippe]

No worry Lesley, I do intend to flood the all world with garden collected rheum nobile seeds in about 7/8 years 

Last winter we got a few seed from the Göteborg botanical garden in Sweden. Apparently (?), this was not wild collected, which could have meant it was collected in the garden itself, but really not sure. I should try to write them to verify. ANyway, I didn't find any informations about a rheum nobile in culture there, or anywhere else, that's why I also asked here on the forum.
The other source last winter was Holubec wild seed through the AGS seed exchange, from which we could get 5 seeds ( only 1 germinated last spring. The seedling is still in the sowing pot, looking good and waiting until next spring to see if the other 4 are going to awake or not).
And we were also given generously 3 other living young plants from the Lautaret alpine garden in France.

With all that I have at least a little material to "experiment" the culture for the first time here.
I'll tell how/if it is going next year.

[Lesley Cox]

Very best of luck with your plants and seed Philippe. I hope it is successful, especially if it is good in a pie.

In pictures we see the magnificent flower stem but I don't recall ever seeing the foliage. I mentioned having had 3 plants which all eventually died but in truth, I don't know if they WERE R. nobile as they were from seed and didn't grow big enough for me to be sure. They were not like any other Rheum I've grown and the leaves were rather deep green and glossy on red stems. I can't remember where the seed came from but probably the AGS.

[Philippe]

Ok Lesley,  I'll tell you how it tastes, a rheum nobile pie



Looking at this picture, I get horrified: those dried brown stalks...Looks like the nobile flowers itself to death  If one gets seed again after, it's ok, but...
Well, another good argument for making pies, and never letting it flower   

Nevertheless you can see some leaves here Lesley, better on the unflowering young plants

[Lesley Cox]

Yes, a bit difficult to see what the leaves are really like. The yellow base of the flowering plant could be the beginning of the stem rather than true leaves. I think it is supposed to be monocarpic isn't it? In which case one would have to rely on seed after a blooming. As for picking out the stem and not letting it flower, that would rather lose the point wouldn't it? I mean, one grows it - or would like to - specifically for the wonderful flower stem. One can dream though.

The landscape with those incredible snowy mounds must look amazing.

[Lesley Cox]

Well it's a while since we posted here but I have good news this morning (Mar 11th) in that I have 7 seeds germinated overnight, of Rheum nobile from Holubec seed. The seed was sown on February 22nd. There are several other little bumps in the grit which I expect to be seeds up within a day or so and I'll take a picture when it stops raining. That may have helped; we have had rain almost every day/and or night for about 3 weeks and the seed pots are quite wet. I guess germinating is the easy part and now I'll have to work out what to do with them as they grow a little. It may be that they should be separated and potted individually while still very small rather than disturb the roots too much. I'm tempted to try some in long tom pots with a very high proportion of gravel and grit, with a little humus. Any suggestions or advice will be gratefully received. As for flowering them, that's a long way off yet, if it ever happens.

[Diane Whitehead]

The first pictures I saw of Rheum nobile were in Living Himalayan
Flowers by Sasuke Nakao published in 1964.

Here are some bits of what is written by the author and his quotes
from J.D. Hooker:  
When the monsoon rain season  comes over the Himalayan alpine
zone, the pastures become thoroughly decorated ......the rhubarbs
grow with their big leaves.

the flowers open in the self-made warm room in which the pollination
insects are working actively........After flowering the stem lengthens,
the bracts separate .... as the fruit ripens, they fall away, leaving
a rugged looking stem.

........... the peeled stem is a superb material for salad ...... and
attentively gathered by the inhabitants so the plant is rather rare
and found often on the inaccessible cliff.


So:  this is Diane again - sounds like soggy grassland rather than
well-drained cliffs might be the preferred habitat.  A picture of a
grinning Nepalese with his arm around a blooming plant shows a
solid groundcover of what looks like a dwarf rhododendron.  I'll see
if I can photograph it.

[Diane Whitehead]

Here is some cultivation advice from The Himalayan Garden  Growing
Plants from the Roof of the World by Jim Jermyn  (Timber Press, 2001)

grow in screes above subalpine meadow zone

in cultivation needs good light, cool deep root run into fairly rich loam with running water
below

embed metre-wide boulders in the loam to keep the big taproots cool

For seedlings:
prick out straight into deep pots  and don't let dry out at all

The next spring plant out at least 60 cm apart.

There will be no leaves in winter.  Leaves emerge in late April or early May
in the UK.

It will take five or six years before they flower (if they do so at all) if you
are very lucky.  The rarity of this event calls for a party and maybe the
newspapers and lines (queues) of eager viewers like when that giant
arum flowers in a botanic garden.

[Lesley Cox]

Well soggy grassland is what they have here right now, with nearly 50mm of rain in the last 24hrs. But they're in their seedpot in the tunnel of course. Jim Jermyn's notes sound a bit beyond me, (metre wide boulders, running water below etc) but I'll do my best. What fun it would be to have a party for the big floral event! I'll give everyone plenty of notice.

We had a rhubard pie for tea tonight, with custard. A less exotic rhubard though.

What a fantastic picture that is Diane. A very happy small boy.

[Bjarne]

I got hands on a Rheum nobile seedling this autumn and have tried to create a habitat for the little plant. I used two half plastic containers with a tap. I have 30-40 cm of sand over the plastic container. Now the drain is open, so it gets dry around the roots. In April, I will close the the tap so it will be moist and cool around the roots. Can not wait to see how it will work.