Paph spicerianum
Howdy again all,
What would we do without these forums (fora?) (We'd have more viable orchid societies I suppose.)
Seriously, thank you all for your input.
Here goes: I have well water which includes the following relevant parameters
7.5 pH
Alkalinity CaCO3 210
Nitrate 50 ppm
Calcium 90 ppm
Magnesium 45 ppm
Soluble sulfate 37 ppm
Other trace elements necessary for plant nutrition are at about zero ppm.
Plants are mostly potted in terra cotta with a mix of 50% medium Orchiata (could they possibly have come up with stupider size designations?) 25% #3 perlite and 25% forest moss. A couple larger plants have larger bark added.
Plants are either sitting on the ground in a greenhouse with nighttime lows around 40F in the winter or in the basement on shelves under metal halide lights with nighttime winter lows around 55F. All species but two generally spend winters in the greenhouse. I did find that sanderianum and primulinum hated the cold with sanderianum showing actual damage. Both were returned to the basement. Selection of cold loving paphs was based on information contained in Birk, Nash or Davis.
Plants are watered with tap water or RODI/rain water, with the greenhouse plants more likely to get well water.
In addition to nitrogen already in the water plants are given a small dose of Florikan (Nutricote) 12-4-11 cal/mag plus minors 180 days annually which helps supplement nitrogen among other things. Those plants which are in areas that tend to be watered with RODI water are given small amounts of MSU to help compensate for the nitrogen already present in my well water. All my orchids are regularly given Kelp-Max.
Because I have hundred of plants in many different families I use widely different fertilizers. But I try to be consistent with fertilizing my orchids. In addition to the above, my paphs are sometimes given dilute calcium nitrate. I'll also sometimes give the orchids, including paphs, a pinch of Epsom salt or chelated trace elements.
Which brings me to my original question. Why, among 25 paphs consisting of at least a dozen species, are the two spicerianums are the only ones that are chlorotic. All the rest are deep green and healthy under nearly identical nutritional and environmental conditions. Speculation is fine.
Thanks again. Steve Herje, SW WI USDA zone 3
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