One often hears a number of questions about aerial roots - those silvery gray "snakes" that grow over the sides of our flower pots - particularly among phalaenopsis:

"Should I cut them off, or leave them alone?"

"When I water the plant, should I soak them, too?"

"Should I mist them or not?"

"When I repot, do I bury them in the potting medium?"

If we think about their function, the answers are fairly obvious.

First of all, they are roots.  Thinking in the classic sense, roots are what the plants use to absorb water and nutrient ions, so we definitely do not want to remove them, and they should be wetted when watering the plant.  It certainly is not detrimental to mist the aerial roots periodically, and can be a real "plus", especially if you grow in a particularly dry environment.

I believe there is another function of aerial roots -  mechanical stability - although we don't typically allow them to do that in our standard potted culture. Consider this:

A phalaenopsis, with those big, thick leaves, has a lot of mass sitting on top of a relatively small base. As if that wasn't enough mechanical stress, in the wild, those leaves act pretty much like "sails" too, catching winds and applying a bending or twisting force on the base.

As the plant matures - growing more leaves at the top and losing lower ones - that mechanical force is magnified by the longer lever arm, so by putting out aerial roots from higher up, the plant is able to "grab hold" of it's environment to stabilize itself, sort of like guy wires on a tall antenna tower.

Ever since that tower analogy occurred to me, I have begun experimenting with putting phals into pots that many would consider to be too large for the plants: I try to have the pot diameter be about equal to the leaf span of the plant. Yes, a small plant with 4" long leaves goes into an 8" pot. Since doing that, I have noticed that all of the plants sink their aerial roots down into the medium, farther out from the plant. In essence, they no longer grow aerial roots at all, as we normally think of them.

So, does that mean we should bury the aerial roots when we repot?  No!

Remembering that root cells grow "tailored" to the environment they are in (see Transplant Adaptation), we can certainly understand that cells grown in "mid air" are going to be different than those that would grow in the medium, and therefore may not function well if submerged.  Left alone, and with the room to do so, the plants will put their aerial roots down into the medium by themselves.