Scottish Rock Garden Club Forum
Cultivation => Cultivation Problems => Topic started by: Rodger Whitlock on September 11, 2010, 10:40:38 PM
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One finds useful information in the oddest places. A few months ago, I chanced across a very interesting blog by a British expat who lives in Tokyo (http://spikejapan.wordpress.com/).
In one of his most recent postings (http://spikejapan.wordpress.com/2010/08/21/cape-sata-the-southernmost-ruins/), he describes a trip to Cape Sata, the southernmost point of the main Japanese Islands (http://maps.google.ca/maps?hl=en&q=arum+dio&ie=UTF8&sll=30.995857,130.662374&sspn=0.025788,0.038538&split=1&filter=0&rq=1&ev=zi&t=p&radius=1.37&hq=arum+dio&hnear=&z=15) in which he mentions being able to discern in the distance Yakushima Island (http://maps.google.ca/maps?hl=en&q=arum+dio&ie=UTF8&sll=30.334954,130.550537&sspn=0.415435,0.616608&split=1&filter=0&rq=1&ev=zi&t=p&radius=22.09&hq=arum+dio&hnear=&z=11) , "one of the wettest places on earth".
As readers are probably aware, Yakushima Island is home to any number of highly desirable dwarf forms of good plants, among them Rhododendron keiskei var. cordifolia (perhaps most familiar as the cultivar 'Yaku Fairy') and Viola verecunda var. yakushimana. I have found the latter very tricky to grow, at least to keep going from year to year. While it is fully hardy (my plants originated in the cold climate of Ithaca, New York), it appears to be touchy about drainage and the amount of water it gets. The best results so far have been in my panacea for tricky plants, volcanic pumice, but winter watering has posed a problem. In the past I have kept my potted plant(s) fairly dry in winter, but now I think that it probably needs reasonable watering even during winter - though not the unending wetness of the Yakushima summer (http://www.eoearth.org/article/Yakushima_(Yaku-Island),_Japan#Climate).
So perhaps V. yakushimana, as it is familiarly known to its friends, will do better for me in coming years.
The same blog describes a trip to Hokkaido, the northernmost of the main islands of Japan (http://maps.google.ca/maps?hl=en&q=yaku+fairy&ie=UTF8&ll=43.47684,143.140869&spn=5.587958,9.865723&t=p&z=7). In passing, the inhabitants' defenses against the fierce winters, snowy, cold, and extremely windy, are mentioned, including pictures of snow barriers. This has clued me in to the ecological requirements of Pteridophyllum racemosum, another choice plant from Japan which I have difficulty keeping going. Clearly it needs considerable water during the summer, and in winter should be kept as cold as possible, but also not allowed to dry out.
Thus, it pays to browse the web widely: you never know where you will find clues to the successful cultivation of tricky plants.
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Yakushima has (according to Google) annual rainfall of 4m, which is somewhat higher than the wetter places in England (3.5m) but way short of the record breaking places at around 11m.
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Plants from Yakushima hould do well then on NZ's west coast of the South Island where the rainfall is measured in metres rather than cms or mms.
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"Milford Sound in New Zeland gets between 7 and 9m of rain each year"
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That's right. I believe there's somewhere in the monsoon zone in India that gets more, but otherwise, nowhere.