Root rot after SH to SH repot (phal)

[sunfire]

Hello all!

I recently repotted a phalaenopsis who had been fully adapted, grown well and bloomed in S/H back into the same S/H container. I thought the repotting went well and was very pleased with everything at the time. I originally transitioned this plant from moss to semi Hydro with no problems.

The pot got knocked over a week later and when I went to put it back together I was really shocked to see a lot of newly rotten and smelly roots that were not rotten beforehand. The root system previously was very robust and now is minimal which has me sad and a little concerned. The plant is otherwise large and healthy. One of the leaves is senescing as is the flower stalk but everything otherwise still looks good.

Is this normal to see with a semi Hydro repot? New roots were actively growing at the time and they still seem ok although the fleshy part of the root tips seem to have dried.

A separate question - as the roots grow into the semi Hydro medium the pot becomes more and more compact. How often would you repot a orchid in semi Hydro in this situation? It seems to me that with less space available for air (with the former spaces having been taken up by the roots) in this always wet environment not good things might happen....?

Thank you.

[estación seca]

What are your temperatures? Ray has pointed out it's helpful to set newly repotted S/H plants on a heat mat for a while.

For fully root-entwined S/H plants you can drop the root mass into a larger container and backfill the space with more LECA.

[Ray]

Root loss upon transplanting is typically a result of the changed environment or due to root damage.

When I repot a semi-hydro plant, I usually just move it to a bigger container, leaving the root mass and it’s held LECA intact, then fill in the volume around it.

[sunfire]

Hmmm. Well, it's between 65–90+ outside right now. I did move it from inside to outside because I thought it would be warmer outside but maybe I did not think about the nighttime lows. I put it in my garage now which seems to be constantly around 80 and will put it in an enclosure if the humidity drops too much.

After I loosened it out of the pot most of the leca fell off the roots. The roots were otherwise very firm and healthy. I basically just put it back in the pot and refilled after getting it in a better position.

Originally Posted by estación seca

What are your temperatures? Ray has pointed out it's helpful to set newly repotted S/H plants on a heat mat for a while.

For fully root-entwined S/H plants you can drop the root mass into a larger container and backfill the space with more LECA.

[estación seca]

I would have done just what you did. Any chance the sun was on the pot and cooked the roots? It could happen in 15 minutes.

[MateoinLosAngeles]

If this is a Phalaenopsis and it's 65ºF outside with S/H's evaporative cooling those roots could've experienced temperatures below 65ºF if they weren't placed on a heat mat. Especially if your RH is low.

[Leafmite]

What may have happened is the roots might have gotten slightly damaged and the various organisms that cause roots to rot were able to enter the roots. Even if you use new water and new medium, these microorganisms can life harmlessly on the outside of roots, only causing issues when the root is damaged.

Letting the roots heal can involve potting the orchids into dry medium and waiting a few days to water or to pot the orchids the maximum exposure to air for a time (so that the roots dry very quickly after watering).

[sunfire]

Definitely not the sun. It was tucked back very far in a corner.

Originally Posted by estación seca

I would have done just what you did. Any chance the sun was on the pot and cooked the roots? It could happen in 15 minutes.

---------- Post added at 11:42 AM ---------- Previous post was at 11:38 AM ----------

I suspect this must have been the issue, probably with some minor root damage, but to be fair it was pretty gentle with the repot and there really weren't any bad roots that I had to trim. Humidity has been above 70% where it was outside. Inside it was prob 40-50% but an pretty much an even 70. Lesson learned I guess. The plant seems to be doing okay so far and the remaining roots I see look ok so that is good.

Originally Posted by MateoinLosAngeles

If this is a Phalaenopsis and it's 65ºF outside with S/H's evaporative cooling those roots could've experienced temperatures below 65ºF if they weren't placed on a heat mat. Especially if your RH is low.

---------- Post added at 11:44 AM ---------- Previous post was at 11:42 AM ----------

Yes. I have done the dry repotting thing with the few orchids I have in bark. But I am not sure sure it is the best idea with semi-hydro? Maybe others can chime in? I have started plants in semi hydro with damp leca but no water in the reservoir in an effort to reduce early root rotting with seemingly good results.

Originally Posted by Leafmite

What may have happened is the roots might have gotten slightly damaged and the various organisms that cause roots to rot were able to enter the roots. Even if you use new water and new medium, these microorganisms can life harmlessly on the outside of roots, only causing issues when the root is damaged.

Letting the roots heal can involve potting the orchids into dry medium and waiting a few days to water or to pot the orchids the maximum exposure to air for a time (so that the roots dry very quickly after watering).

[Leafmite]

I do not do semi/hydro so I have no idea. I use lava rock as a medium and so it is pretty easy to do this. I am just guessing that this is what happened to your roots, based on...experience (I have made every mistake in growing orchids...and hopefully learned from them all).

[Ray]

When I repot, I flood the pot immediately. However, in cases where I have replaced the LECA, I let the exposed root system dry for a day before putting it back in the pot.