phals in leca have black roots!

[greenpassion]

I have several phals that prior to now have been doing fine. Nice green roots, blooming well. But today I noticed that the roots are nearly black. I keep the temps in my house at 60 thru the winter. Last year I think I had them on a heat mat, which is the only real difference I can think of. My question is will cooler temps cause root rot?/


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[Leafmite]

I believe the cooler temperatures are likely the cause of the rotting roots. There are three reasons that this could be the cause. Usually, plants/orchids can tolerate wetter conditions in higher temperatures and need drier conditions in cooler temperatures. If you are watering often and the medium is staying wet, the roots will rot. If you are growing S/H, there may not be enough oxygen in the water to prevent rot. One of our Orchid Society members grows all her orchids hydroponically and she has a professional set-up that bubbles air through her water.
The last cause could be too much fertilizer. In cooler temps, an orchid doesn't use as many nutrients and the fertilizer can build up and burn the roots. I use a slow release with those that are still growing and don't fertilize the ones that are not.

[AnonYMouse]

Did the black roots grow into the LECA or did they exist prior to repotting into LECA?

I can't see the old roots of my Phals-in-LECA but one of my Sedirea (like the Neos, I'm not reclassifying the genus per the whims of taxonomists) has black old roots. The roots that grew into the LECA are green. The old roots don't seem to be negatively affecting the plant.

---------- Post added 12-07-2014 at 12:28 AM ---------- Previous post was 12-06-2014 at 10:48 PM ----------

Oops, didn't notice where this was posted. Ignore previous post if you are specifically asking about roots in S/H.

I grow my Phals and Sedirea conventionally in inorganic materials.

[greenpassion]

Thanks for the responses.In answer to Anons question, all the roots were a very healthy green. I've always seen nice bright roots all through the leca. I'm pretty certain that this problem is due to the roots becoming too cold. I'll unpot them, cut out any dead roots, then put them back on the heat mat I had them on last year/@

[Ray]

Very likely, it's evaporative cooling that has hurt them.

Phalaenopsis, in nature (for the most part) are very HOT growers, rarely seeing temperatures lower than the mid-, to upper-70's, but they are reasonable tolerant of a bit lower.

Drop your temperatures into the 60's, couple that with winter's dry air, and evaporative cooling from the open, airy medium chills 'em even more - to the point of failing.