I live in arid Phoenix, Arizona. I don't have a greenhouse. My house has relative humidity 35% to 60% depending on the season and where the dogs are sleeping. I have always liked Vandas and I can certainly give them warm temperatures, but I never tried them because of their reputation for requiring high humidity.
After reading all of this thread I was willing to give it a try. In the second week of June 2015 I received some Vanda seedlings from motesorchids.com. I unpacked the plants outside by my trash container so I wouldn't get paper shreds in the house, then put them into a bucket of rainwater to soak for 30 minutes. Unpacking outside was a mistake. I am fine shirtless in Arizona sun, but some of the plants sunburned after unwrapping, before going into the bucket. None was severely damaged, though.
The beautiful plants arrived much larger than I expected, with big healthy root systems. I was able to fit them into various taller-than-wide plastic containers. Some originally held isopropyl alcohol, some pomegranate juice, one vitamins and one held rum. I only used containers that were transparent or white, ones that didn't block all the light. I cut the tops off to make holes big enough to fit the roots without damaging them, but small enough that the leaf fans would not fall through the hole. I used a sharp serrated knife or a scissors.
I have a 20-gallon aquarium under two 40 Watt CFL spiral lights on a timer (200 Watt equivalent each.) I put the containers along the aquarium; the plant crowns are near the top of the aquarium. The photo below this post is from today. My house is pretty warm during summer, usually in the 80s F, and that room is warmer when it gets morning sun on the window.
I began spraying roots and plants morning and evening with rain water. Initially I didn't have any water reservoir at the bottom. When some MSU fertilizer and Kelp Max arrived from FirstRays a week later, I added it to the rainwater at the rate of 1/4 teaspoon per gallon MSU, which I think gives somewhere around 45ppm nitrogen. I added 2 teaspoons Kelp Max per gallon to the water as well. I continued to spray with that at least twice daily. The plants looked healthy from the start, aside from the sunburned patches that dried up. The Vandas kept their fat, healthy roots and began growing new roots. The Ascocentrum curvifolium continued having healthy leaves but its roots shrank, though they are still alive and functioning. All the plants continued lengthening new leaves. I don't know how fast Vandas of this size should grow new leaves so I can't comment on how well they are doing that.
I went out of town the second week of July, and nobody was there to water the plants. Before leaving I put a 45PPM nitrogen MSU fertilizer - KelpMax water reservoir in each container, with the level just touching the lowest roots. I knew the water would evaporate down below the roots before I returned.
When I got back most of the plants looked as though nothing had happened, but a couple were slightly wrinkled. I soaked them all in rain water for an hour and the next day they all looked good. I put more MSU-KelpMax solution in the reservoirs so the lower roots were always touching the water. Instead of spraying the plants and roots, twice or more per day I would just tilt and rotate the containers to wet all the roots with reservoir water.
All the leaf fans continued looking good. The roots didn't look quite so good, though. Some of the new roots stopped growing but kept their red shiny tips. The Ascocentrum continued with thin roots. Some of the plants' root tips touching the water turned black; others remained healthy. I cut off the dead black ones and lowered the reservoirs in all the containers so the roots aren't touching the water.
I thought maybe that was too much exposure to KelpMax and/or fertilizer, so I switched back to spraying with rain water with 45PPM nitrogen MSU, no KelpMax. The new roots perked up and began growing again.
So, those are my experiences so far. I don't know whether they're getting proper light, and I don't know whether they're growing normally or too slowly, but they don't look bad. My guess is Ascocentrum curvifolium wants more humidity than I'm giving it, and that's why its roots shrank. Its leaves look fine, though. And, after reading more about KelpMax on the FirstRays site, I think I'll only treat once per month rather than daily.
I seem to recall reading on this list that a couple of years ago a lady in Phoenix tried with Vandas but had a bad experience. If you're still reading, try again! I think frequent wetting of the roots to prevent drying is more important than relative humidity.
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