Re: How to divide Cypripediums

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Abgeschickt von Holger Perner am 30 Oktober, 2007 um 01:44:54

Antwort auf: How to divide Cypripediums von Michael Weinert am 13 Oktober, 2007 um 09:41:59:

Hello Michael, hello cyp friends,

It has been some time since I checked the forum, there is simply not much time left with the amount of work around me.

I was very pleased with the excellent and highly instructive contribution on dividing cypripediums by you, Michael! I fully agree with all the statements you made and the comments by our experienced fellow growers. And yes, Tom, divide a big clump to be sure it survives. Michael refers to a big clump, 25 years old, that died in somebody’s garden. It might be the very case I witnessed personally in the garden of my old mentor Otto Moeller. Every year in May we stood in front of his largest clump of Cyp. calceolus (over 20 years old), carrying over 100 flowering stems. And every year Otto said how urgent he would have to divide it but couldn’t. The clump was too impressive, the fear of something might go wrong too big, and actually the clump too heavy and too big to be handled by Otto, who was than already in his early 80ies (and today in his nineties still orchid gardening). Of course friends, including me, would have helped him, but the division was never made and so the inevitable came: the clump died within months. Only peripheral divisions made from time to time by Otto over the years and planted beside the clump or elsewhere in the garden easily survived, proliferated and soon filled the garden with about a hundred flowers or more (the total of several small clumps) each May. Would the big clump have been divided in time, the garden could now have thousands (I am not exaggerating!) of flowers of this clone each May.

What about big clumps in nature? As I write this here in Huanglong National Park, I am surrounded by 12 Cypripedium species that grow in the wild, the closest species Cyp. tibeticum at the slopes just behind my window, the most numerous Cyp. flavum same 5 km away in the Huanglong valley (an estimated 10 000 flowering stems each June, accompanied by approx. 5000 Cyp. tibeticum and 5000 Cyp. bardolphianum). There are large clumps of Cyp. flavum in the valley, some certainly with 40 stems or more, but these clumps are rare and only grow where soil conditions are so that a compacting between the roots is inhibited by many tufa clumps and fresh nutrients are provided annually by the very porous substrate. In Northern California and Southern Oregon you might find enormous large clumps of Cyp. californicum, but they grow in conditions very close to hydroponics, so again constant refreshing of nutrients and hindrance of compacting substrate at rhizome level due to pure gravel. 

Attempts to grow such large clumps in cultivation will fail on the long run, so divide in time! The examples are really just the exception of the rule: 99.9 % of all cypripediums with compact rhizomes here in Southwest China do grow as single shoots or small clumps. Species with long creeping rhizomes like Cyp. guttatum, japonicum, bardolphianum or micranthum form specimens with numerous shoots, dozens or even hundreds per clone are certainly not exceptional. But each single shoot grows 5 to 20 cm or more apart from the next one!

A last word on timing for division. Large clumps, especially such as the one Michael showed, should be divided in autumn, when all new growths are fully developed and have just entered dormancy. This will reduce damage by handling. Michael clearly described how much force has to be applied (don’t be halfhearted when tackling such a specimen or you would cause more bad than good, and really, do not use a knife or other cutting tools except as the last resort, a blunt stick or something similar might be helpful, though, when poking into a dense rhizome to form a gap where fingers fail... ). With smaller clumps, especially those with wider spaced growths or creeping rhizomes like Cyp. formosanum I prefer to divide just after flowering because than the newly emerging shoots and roots can easily settle in and are fully established until dormancy. However, dividing in autumn also gives excellent survival rates and vigorous plants the next season, as Michael clearly stated. And what Darcy wrote is also very true: dividing in July and August, during the main growing period when the new shoots and roots are in full development and at their most vulnerable, is the worst time and should be only done when absolutely necessary.

So good luck with your divisions and do it as the Romans did: ‘divide et impera’ (divide and rule) - or compacted root bales and a nasty rots will rule you out!



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