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Abgeschickt von Michael Vaughn am 06 April, 2005 um 06:43:24
Last year I wrote a lengthy article detailing my experiences in cultivating Cypripedium acaule. This post is to reconfirm my succesful points and to give further information on observations I have made since then.
Most of the information I'd given in my previous article has been very successful in the continual cultivation of this presumably difficult species. The sifted pine duff has provided the perfect texture and acidity and the few plants I had experimented with in a 50/50 blend of duff and perlite I have long since moved into the pure duff. I made this choice based on the fact that both plants growing in the pure duff and in the blend responded with no more or less vigor than the other, and that the pure duff dries out less quickly. Even the alba form I purchased last fall has taken quickly to the pure duff without problem.
The vinegar and water mixture has continued to be quite useful in maintaining a low pH, and a brief mistake I made in the mixing ratios provided me with further information this year. Due to my mistake in assuming a watering jug was a full gallon when it was not I ended up mixing roughly 3.5-4 oz of vinegar per gallon of water proportionally. Although the acaule didn't suffer any damage or dieback they did begin to suffer some mild chlorosis. However before I realized my mistake I assumed it was a nutrient deficiency problem arising from my use of pure organic matter. This led me to move onto a fertilizing regime. Even with the excess acidity the fertilizer reduced the vast majority of the chlorosis and now that I have corrected the ratio (now using 1-1.5 oz vinegar per gallon) the fertilizer has greened them up almost entirely.
It is typically believed that since acaule grow in low nutrient environments they do not need fertiltizer, and that adding fertilizer will increase microbial activity and damage acaule. With at least a dozen feedings thus far my initial results seem to counter this assumption, and I was told of another acaule grower who boastfully claims he can divide his acaule every year since he feeds with a diluted mixture of mir-acid. So even if acaule doesn't 'need' fertilizer it doesn't necessarily mean that it couldn't 'use' fertilizer.
However before anyone goes and attempts to fertilize their acaule I think one point must be made. The vast majority of commercial fertilizers use Urea as a nitrogen source since it is inexpensive. Urea needs microbe activity to break it down into an absorbable nitrogen form. Given the acid environment I see two potentially dangerous things that could occur for acaule:
1) The urea could cause a population explosion in soil microbes despite the acidity, which could then attack the acaule roots.
2) The acidity could continue to surpress microbe activity and continual feeding could cause a build up of urea in the soil, which would not only fail to provide nitrogen but may burn the root tips.
Given this I'm using only the 'Grow More' brand premium orchid food 20-10-10 blend which has only ammonical and nitrate nitrogen and has the added benefit of having no calcium. I use a tenth of what the label suggests every time I water, and occasionally water with pure water to leach out any extra salts that might be building up.
I hope that more people start to grow this lovely species and if anything I pointed out is unclear feel free to post a reply.
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