Repotting questions
 

Hi Guys,

I have had orchids (semi-sucessfully, I guess you could say) for years. I have 5 phals and two Oncidium. The Oncidium are new to me. I haven't had a Phal die on me, but I have some repotting coming up of my oldest Phal, and I am a little nervous...

My questions are these;

1) I use Better-Gro Orchid Bark in ceramic pots, some "orchid" pots, others not. Any thoughts on this? Is there better?

2) When repotting, is it really true that above ground roots should not be buried?

3) Repotting is best done soon after blooms drop, correct?

Hi sunbird!
1)Orchid pots have holes or slots on the sides to give better air circulation of the roots since the roots extract the primary building block from the air which is carbon dioxide.

2)It depends on the orchid, phals have roots in the pots that serve only to anchor the plant while the exposed roots feed the plant. Cattleyas have all functional roots below the media. Though I'm not sure about Oncidiums.

3)Yes, or when new growth starts.

Good luck!

Sorry to correct you, but some things are false in what you write.

Having holes/slots in the pots is indeed for air circulation, but is not for CO2 fixation. Although some roots do photosynthesize (like phal roots), CO2 fixation is done nearly entirely through the leaves. The photosynthetic role of the roots is fairly minor compared to what the leaves do. Holes in the pot are for air flow, since most orchids are epiphytes, so they need a loose airy medium.

About the roots, ALL orchid roots feed/bring moisture to the plant. There is no such thing as functional and non functional roots, unless some are dead! In the case of phals with their aerial roots, the same holds true, it's just that the ones in the pot have the additional job of anchoring the plant, and the aerial roots search for moisture in the air.


If a phal has plenty of roots in the pot, there is no need to stick the aerials in there when repotting. Aerial roots have a different structure than pot roots, since they grew tailored to living in the air, which is much dryer than in the pot. Sticking them in the pot might make them rot since they are not used to so much moisture.
In the case of phals, clear orchid pots are better since they not only let you monitor the roots to know when to water(silver means dry, green means they still have moisture), they also let light to the roots, so they can do their bit of photosynthesis.

Thanks Camille,
I do have a background in plant physiology, so I was pretty aware about CO2 uptake.

I guess, a more specific question is this:
My phal needs repotting, and it has roots hanging out everywhere! What is the point of repotting if I had vet leave all of those aerial roots hanging out everywhere?

Unlike other plants you don't report orchids because they need more space for their roots. You repot them when their medium breaks down too much to support a healthy 'chid. (Actually it may outgrow the pot as well but arial roots are not a sign of this).

Arial roots have grown that way and have a different outer surface to ones that have grown in the medium. For this reason they do not easily adapt to growing in the medium. They can adapt and I have had ones adapt on a Phal which had lost all roots from under the medium. Many people report that arial roots can rot if put under the medium because they are not adapted to it.

Besides all that Phals tend to like having arial roots, if you tuck them in a healthy Phal will probably just grow more.

Here's my two cents:

1) There is better, but I use Better Gro stuff too. I use the "special orchid mix" with all the charcoal and course pearlite in it as well. Just personal preference, if it works for you - it works for you.

2) Roots are really good at tailoring themselves to various environments they grow in. The problem is they don't change once grown. I tuck in any that let me and leave the stubborn ones out. No worries.

3) See #2. Repot any time NEW roots are growing so the plant quickly established in its new pot.

4) Don't sweat it. ;)

Thanks guys. I have managed to keep these guys alive for a while, but it is hard to know what is best sometimes.