Why are Vandas different than Phals?

[sand_tiger86]

I know they're both on completely opposite ends of the spectrum when it comes to light requirements, which makes sense to me. However, they're both monopodial and their root systems are almost identical in regards to thickness and general appearance. So, why is that Phals love their roots to stay just slightly damp but Vandas hate damp roots, yet want to be watered all the time? What makes Vanda roots rot so quickly when they're so similar to Phal roots?

[cdayinflorida]

I water my vandas up to 3 and 4 times a day so rotting roots are not a problem when hanging. The biggest issue with rot in vandas is water standing in the crown. But all monopodial plants are like that. Most really hate cold weather. They like heat, light, water and air movement. They are also heavy feeders.

[Halloamey]

They might look very similar in morphology but the roots are very different anatomically. Vandas have evolved to occupy a niche that gets wet very often but also dries out very fast, hence their roots are more like sponge channels that have much more velamen as compared to Phal roots. Their function is to absorb as much water in a short amount of time and transport it to the leaves quickly. Whereas most Phals have evolved to occupy a niche that stays constantly moist, thus their roots have less velamen and somehow also act as the a tiny water storage organ. Whereas in Vandas most water will be stored in their much fleshier leaves.

[tucker85]

It always helps me to think about the environment the orchid grows in. Phals have large leaves because they come from areas that do not get much sunlight. The lack of sunlight means the environment will stay wet longer. They often grow fairly close to the ground in dim, wet, mossy areas. Vandas have very thin leaves because they grow higher on trees where the sun is brighter and the breeze is stronger, as a result, the plants dry much quicker. In southeast asia it can often rain almost every day but when the sun comes out, it's hot and bright. So vandas get heavy tropical rains and then dry out quickly in the hot tropical sun.

[cdayinflorida]

Excellent explanation, Jeff.

[Brutal_Dreamer]

Nice thoughts Amey and Jeff!

cheers,
BD

[BioVivara]

Is it possible to use a misting system for these, provided the mist is directed to the roots?
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[Halloamey]

Yes, it is possible and highly recommended for orchids. The best way to grow them, as close to natural way, would be to grow them mounted so that they dry out quickly and then water them frequently. Not getting the foliage wet will help against fungal infections and rots.

[sand_tiger86]

Mounting orchids is incredibly difficult in a home/apartment, though. Most indoor facilities simply don't stay humid enough for aerial roots to thrive, even if you mist and water frequently. Every aerial root coming a Catt, Phal, you name it, has shriveled up and dried out no matter how often I mist them.

[BioVivara]

I had the same problem SandTiger Have you tried using a vivarium/terrarium? That's how I keep mine. I built my own and added an internal fan for air flow. This keeps humidity around 70% and my plants have stayed pretty happy.
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