Phals in vivarium with automated misting

[harpspiel]

No orchids want to be “soaking wet” (well there are a few orchids that grow in streams in situ, but I would still bet that in an enclosed environment they don’t like water on their leaves). Pleurothallids tend to do pretty well in tanks where they stay moist all the time and get some air movement. Vandas could work in a tank but it would have to be high humidity/strong air movement/intense light, with less frequent watering. So they probably wouldn’t be happy in the same tank as Phals and Pleurothallids.

[Draikan]

Originally Posted by Shadeflower

One important thing to note though is that the reason orchids in a terrarium always look freshly watered is because most likely they have. If someone takes a picture, they will water their orchids at the same time. It just makes sense to do it at that time so they will always look wet on the picture but they will dry out in between.

I do this. The plants looks best and most exotic when they are wet. So I take pictures after watering when I am already working on plant stuff.

I grow a lot of mini pleurothallids of all kinds, and I don't have any that want to BE wet for more than a few hours. They like to GET wet, and then get lots of fresh humid air to dry them off. Fresh dry air is bad, fresh humid air is good. And when I say fresh I basically just mean it has to be moving and <100% humidity.

[Thriodien]

Originally Posted by Draikan

Fresh dry air is bad, fresh humid air is good. And when I say fresh I basically just mean it has to be moving and <100% humidity.

Yes, that's the thing, but how do you do THAT?

I used to have a terrarium full of phal species mounted on cork but i just couldn't keep the bare roots happy this way. When i sprayed them i was afraid that the leaves might get some kind of rot so i ran the ventillators right after that until the leaves were somewhat dry. But that caused the roots to dry out too much even though there was sphagnum moss around them (it obviously dried as well). So i shifted to leaving the doors open for a while after watering but then i was left with only 50% humidity in the terrarium... Seemed like there's no proper way to do it and yes, you're right, that's the key, fresh, humid and moving air! But how???
Now I'm planning to give this terrarium experiment another go so i already have a misting machine but now i'm thinking maybe i should've rather invested in a humidifyer?...

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[Draikan]

In my experience, the plants are more tolerant of water on them if the air is not still. I'm not certain, but I think it may have more to do with oxygenation than wetness. It seems to me that in still air, if the roots or leaves stay wet, the water reduces the amount of oxygen that can get to the tissues and bacteria that keep the plant healthy. If air circulation is improved it helps oxygen diffuse through the water and get to the plant while it's still drying off.

As for how to actually do THAT in a typical terrarium? It is hard to suggest something that will work for everyone. We all have different climate, tank size, heating, lighting, ventilation, species, mounting, watering, etc...

Here is what I would recommend as a reasonable starting point for most people:

1) Use a small fan for internal circulation, and run it 100% of the time day and night. Something like this, with a power supply like this. Either point the fan up or forward at the glass of the tank. If it blows directly on the plants it may dry them out too much. This will eliminate all stagnant spots in the tank, helping the plants to dry off AND helping them tolerate being wet.

2) Do not use a fan to blow outside air into the tank, or to blow tank air to the outside. This will be way too drying in most climates. Mostly seal the tank, but leave a small opening for passive air exchange. This small opening combined with the internal circulation fan will slowly mix in external air and dry off the plants. Slowly adjust the size of your opening until the plants are drying off about 12-24 hours after watering them.

3) build a drain or false bottom into the tank and water your plants to saturation. Literally soak them. This cleans out the mounts and makes sure they are getting fully rehydrated. You don't want to risk a plant only getting slightly wet, and then spending a few days in your well circulated air. The drain will let you collect and remove the water easily. If you let it collect in the bottom of the tank, all your nice circulation will be trying to evaporate that water instead of the water on your plants.

This is how I first found success with orchids in terrariums, and what my current methods evolved from. You will need to tinker with it, and you may need to adjust it seasonally as the conditions in your home change. If you get this working and you want to keep experimenting or improving, you can try adding a humidifier, timers, humidistat/thermostat, etc. You can also try adding more internal circulation, in my experience the plants like more internal airflow IF you can keep the humidity up. The amount of air movement we are providing is pathetic compared to an actual outdoor breeze.

TLDR:
1) active circulation
2) adjustable passive ventilation
3) water to saturation
4) have a drain

[Thriodien]

Thank you so much for the awesome tips! I haven't thought about e.g. drainage before but seems useful.