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Watering New Guinea montane orchids

Discussion in 'Orchid Culture' started by Matthew Speights, Feb 19, 2021.

  1. Matthew Speights

    Matthew Speights New Member

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    So, strange question for the other New Guinea orchids fans out there. I have a refrigerated (55° nights, 75° days) paludarium in which I grow high-altitude New Guinea Dendrobium (D. cuthbertsonii, D. vexillarius, D. parvulum, etc.), Bulbophyllum, and other genera. Humidity is always over 90% with strong air circulation, and I use an Inkbird thermostat to map the daily temperature variations to roughly the same as temperatures in Mt. Hagen, PNG (adjusting for the time difference). I've noticed--looking at hourly weather--that in Mt. Hagen it usually rains in the afternoon and evening. So, my mister runs at 3:45 p.m. and 10:00 p.m. every day. I know this runs contrary to popular wisdom (to generally water in the morning, and only water at night when humidity is low), due to risk of fungal infections. However, I've never had any issues, and it does match what these species experience in the wild. That said, I'm considering experimenting with a more typical morning watering schedule, just to see how it affects them. Any thoughts, especially from anyone else who has grown similar orchids or who grows in a cooler terrarium?
     
  2. Alex Shepack

    Alex Shepack Member

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    So, I know Andy also waters his greenhouses at night - quite heavily from what I've seen.
    I've also had a similar thought, because in most of the wet tropics the rain comes in the afternoon/right around dark for most of the year. I imagine as long as you keep the fans/ventilation running at night it should be fine.
    It may also help with evaporative cooling to drop the temperature even more? I'm curious to see what others say.
     
  3. Marni

    Marni Well-Known Member Staff Member Supporting Member

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    About 30 years ago there was an orchid grower in the SF Bay area who had done some collecting in PNG and South America. He had some wonderful plants when they were quite hard to come by. He also had his misters come late in the day because "that's the way they grow." He was always offering to give you a piece of a plantthat you admired "as soon as the plant gets big enough to divide." But they never got big enough. They would get a growth and loose a growth and never got over a few growths or leaves. They just struggled on. It was something of a joke in the area.

    It really depends on what works for you. I do know a few people who water at night, but I'm not one of those. It feels different in my greenhouse at night than it does in the forest and I can't really duplicate that.
     
  4. Ray

    Ray Orchid Iconoclast Supporting Member

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    I think we need to think as much about how it rains as much as when.

    When it rains, it rains! Lots of volume for a fairly long time, so there’s little opportunity for pathogens to settle and multiply. That’s quite a bit different from misting to dampen.
     
  5. Matthew Speights

    Matthew Speights New Member

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    Thank you all for the input. Marni, I'm fairly sure I know of whom you speak. I grow a Bulbophyllum species he discovered, and I visited his successor's greenhouse in San Francisco in December 2019 (a really fantastic place, and a great guy!). I've never had issues with fungus aside from the one time the fans and refrigerant system were off overnight. The paludarium is small enough that with twin fans it really has strong air movent, even as it is almost permanently damp. I do wonder whether plants like D. cuthbertsonii might not grow better being more wet at night, as long as they have sufficient air circulation, but I agree that we can only go so far in replicating natural environments. It's worth experimenting, so I think I'll try a test of morning watering for a little while, just to see how my orchids respond.

     
  6. Marni

    Marni Well-Known Member Staff Member Supporting Member

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    I've never been in PNG so don't know what the climate is like. Please let us know if you find a difference.
     
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  7. Matthew Speights

    Matthew Speights New Member

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    Unfortunately, I had to quit the test after day two. My paludarium has limited circulation with outside air (not fully airtight) because that's necessary for the Peltier cooler system to drop the temperature down to 55° at night (it's essentially a little refrigerator; I built it with double-walled glass and insulation) and because the office I'm in had pretty bad air shared with a welding shop (the paludarium is on my desk). So, there's minimal evaporation, and everything stays close to 100% humidity. When the Mistking runs, it leaves water on the glass for hours, so if I mist in the morning, I can't see my plants all day. :)

    Based on observed plant responses, I will continue for now with the afternoon watering (3:45 p.m.). That does reflect the kind of misty, mossy montane forest environment that something like D. cuthbertsonii might grow in. Many plants are growing very well, and those that haven't really taken off don't seem to have issues with fungal infections. I'm sure that would be an issue if I didn't have strong air circulation. The fact that they're all mounted (except for one terrestrial) probably helps as well. The only drawback I've seen to such high humidity is that moss wants to overgrow everything. Some orchids seem to like having moss over their roots, and some don't.

     
  8. Marni

    Marni Well-Known Member Staff Member Supporting Member

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    Well, you answered the question for you current set up.
     
  9. Chuck-NH

    Chuck-NH Well-Known Member

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    Interesting discussion. I tend to agree with those that have made comments about not exactly being able to recreate nature and that forces adjustments. From a greenhouse perspective, I’ve had experience with PNG cool growers since the late 80’s. Regardless of the air movement, etc., I’ve found in the Northeast of the US that wet plants at night equals decline in health. For my conditions, I find the plants are happiest when they are dry by mid-afternoon. Humidity in the greenhouse generally rises to 85+ percent at night, so I think that keeps the aerial roots happy. I only water later in the day when there is a heat wave in conjunction with low ambient humidity.

    Here are a couple Dendrobium vexillarius that have not seen wet roots or foliage in the evening for many years.

    6701C1BC-1842-4E5F-B9DA-CFFD02C0FA50.jpeg

    4F76D33A-3C64-4B33-90FF-904135261AD4.jpeg
     
  10. Matthew Speights

    Matthew Speights New Member

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    20210225_115231.jpg I'm not sure that I'm not causing issues for my plants, but most of them seem to be doing well. Maybe something about the terrarium environment is different from a greenhouse setting (although I can't think what). It does seem like some orchids require adjustment to the high-humidity environment. I have a Bulbophyllum ankylochele I got from Ecuagenera that over several months shed its old leaves and grew new ones. My Dendrobium vexillarius is growing quite well, but perhaps that's because of its numerous aerial roots, which dry more quickly.[​IMG]

     
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  11. Chuck-NH

    Chuck-NH Well-Known Member

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    Great looking plants! And as they say, the plants don’t read the books, so if something works for you then stick with it .
     
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