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DAMNED DISAS!
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I began trying to grow disas several years ago, fascinated by the large and lovely unique flowers. A fellow member of my local society had been growing them for years, visiting New Zealand annually during disa blooming season, making crosses, and bringing back seed. He gave me a couple and I did some research and started trying to make them thrive. To make a long story short, for a couple years I got new disas in the spring, grew them on through the summer (and substantial losses), and then killed them over the winter. I was unable to provide the cold nights they require, especially during the winter when they were indoors. My growing skills improved gradually with experience. I managed to keep a higher percentage alive through the hot summer nights, but the third year they still died shortly after I had to bring them in for the winter. I had in the meantime begun purchasing them and my friend kindly kept giving me a few more to kill each year. In the process of purchasing, I was informed by Michael Gallagher of Dablo Disas that I would have to have a TDS meter or I would not be allowed to purchase them. Smart man. Since disas do not tolerate impure water, the TDS meter is necessary to evaluate water quality, a total TDS of less than 200 being required for success (and even less if possible). I had begun storing and using rainwater in the interim, in a discarded RV water tank. My tap water tested out at about 420 ppm with the TDS meter; the rainwater at 11 ppm. I also bottom water them, and have them sitting in a cat litter box and a sawed-off 5-gal 'pickle bucket', with a 1/4" drainage hole which I plug with a pencil when soaking them. One problem I had early on was growing them standing in water, recommended by one grower. Didn't work for me. They rotted. Now I have them potted in plastic pots in a 50/50 mixture of chopped sphagnum (real, long-fiber NZ sphag that I chop myself, not the shredded stuff sold prepackaged. I chop it about like coarsely diced vegetables) and #4 sponge rock. Bottom watering prevents the sphagnum from becoming packed, and it remains as it was when potted, loosely shaken around the plants. I water them when I think they will begin being dry tomorrow, usually no more often than my other orchids, about every 3-4 days. Occasionally, on really hot summer days, I will water in order to cool the roots off. I fertilize once a week or two with MI formula fertilizer, at half-strength from what I use on the rest of the orchids. The fertilizer-enhanced water has a ppm of 170 or so. Oddly enough, in the interim, my city water has dropped to a ppm of 273, revealing the necessity of frequently re-checking water quality.
In order to shepherd the disas through the winter, I made a change. I place them in the small growroom during the day for light, and then when I turn the lights off, I carry them to the large grow-room, which has some air vented in from outside, and place the containers on the concrete floor, where it generally gets down to 50'F or so, sometines a little cooler, sometimes up to 55'F, but always at least that cool. The result: flowers. Two plants (out of eight at the time) bloomed last year, one unfortunately at Christmas, with the flower down in the crotch of the plant (above left), which I hear is not unusual for out-of-season disa flowers.
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