Overwatering issues with s/h?

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You don't need a lot of air circulation at RH 45%-55%. There will be little chance of fungus growth at those humidities.

You can water more often or put something on top to increase moisture a little at the base. Sphag will also dry out rapidly.

A rooting orchid needs frequent attention in any circumstances. I would consider spraying just the top of the LECA with one or two pumps from a spray bottle, daily, until new roots have formed and entered the medium. This isn't standard S/H teaching but your plant has next to no roots in the medium now.

[smokinjoe1952]

ES,

Thanks for that info. Since it is a grow chamber, I can easily raise and control the humidity.

I have a mix of Phals, Catt., Onc., Phrags and Paphs.

I put my old humidity tray in the chamber, filled with water and put a waterproof fan on top. It is evening now, so the lights are off.

I am reading 70 degrees and 77% rel. humidity.

What would you consider an ideal relative humidity level given the above plant mix knowing that I have more than adequate air flow?

I believe I could easily hold approx. 65% both day and night with an inexpensive controller on the fan.

I have spent quite a bit of time and $$ on the chamber, so if a few more little tweaks will optimize the environment, I want to do it.

Thanks to EVERYBODY for the feedback. It can be the little things the new growers like myself really need to be successful.

SJ

---------- Post added at 10:17 PM ---------- Previous post was at 10:15 PM ----------

I should add that I assume 77% relative humidity is too high, so will add a controller or only run the fan on the humidity tray during the day.

SJ

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77% isn't too high. It's probably not necessary for those plants, but they will like it. The plants you listed generally tolerate somewhat less humid environments than some orchids.

Everybody's conditions are different through the year. In my conditions 60% relative humidity seems to be an inflection point beyond which things do much better.

There will be less trouble with fungus at lower relative humidity. But, if you're not having fungus trouble, don't worry about lowering the humidity.

People do seem to think that more air flow is important at higher relative humidity for many orchids, and that this helps prevent fungus. I have read here that some miniatures and some cloud forest orchids do poorly with any air flow at all, but the ones you listed are fine with it. In the previous message I was pointing out that at a relative humidity of 65% there is not a large risk of fungus, so there is no need to have a great wind blowing in your terrarium. A little air circulation would be fine, like that provided by a computer motherboard fan, for example.

It is definitely better to have high humidity when trying to resuscitate orchids with poor roots.

[smokinjoe1952]

Again, great info and recommendations. I will raise the humidity from the current 45 - 55% range. If I can maintain 65% day and night, do think that might eliminate the need for sphag on top of the LECA to hold in moisture????

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Originally Posted by smokinjoe1952

...If I can maintain 65% day and night, do think that might eliminate the need for sphag on top of the LECA to hold in moisture????

I don't know. Try it. Remember the aim, not to let the base of the plant where new roots should emerge stay dry for an extended period of time. It should also not stay wet.

[smokinjoe1952]

If any of you are AOS members, and I suspect many of you are, go to the AOS website and search for HUMIDITY.

Look for this article:

"The Importance of Humidity and Air Movement in Successful Orchid"

The interaction between air movement and humidity is not something I have really thought about.

Maybe most of you have read this, but I found it to be very informative.

Also, I have been considering 45 - 55% relative humidity very adequate, but further research and feedback on this thread indicate higher levels are very beneficial.

SJ

[smokinjoe1952]

Just an update on this topic. It has been a little over a month since I:

1. Raised the RH from 45/65% day/night to 65%/75 d/n.

2. Watering once a week even though most pots have very little water at the bottom and some occasionally have gone dry.

3. Re-poted some of the Phals and 1 onc. using larger LECA than what I was currently using.

The change in the Phals is significant. Of the 8 plants, 7 of them are showing new leaves, new root growth, and no aerial root dryness. The leaves that were desiccated (leathery) are now becoming more firm.

I would GUESS that the most significant change was raising the humidity, although the extended watering schedule I assume will help with my black root problems.

It is obviously too early to tell whether the larger LECA will benefit the Phals.

The Catts., Phaphs., Phrags and Onc. didn't seem to notice the humidity increase or watering schedule change, meaning no change on how they appear.

The grow chamber has been up and running for about 1 year now. I had always thought that RH at 50% daytime was adequate, but with the airflow I have, which is not excessive, it seems that it was too low given the air movement in the chamber.

Still Learning!

SJ

[Ray]

If the pots go dry between waterings, you're not watering frequently enough, so are not growing in semi-hydro culture, but are really just using LECA for traditional culture.

When you move a plant into S/H culture, we expect that the old roots will die and rot. It's perfectly normal, and that's why the plant needs to be just initiating growth of new roots when you make the change. The new roots will support the plant as the old ones die.

[smokinjoe1952]

Ray,

As always, I appreciate your knowledge and experience. I would like your comments on the following:

My culture pot supplier (2 pot with gauge) clearly states to let the pots go dry before watering again.

You have stated many times that allowing the pots to go dry is simply using LECA as an alternative media in traditional orchid culture. I'm SO confused.

I am not sure what the solution is, but have a hunch that both methods will work.

My question would be:

WHAT ARE THE ADVANTAGES (in terms of plant health, growth, flowering, etc.) OF S/H, VERSUS USING LECA SIMPLY AS AN ALTERNATIVE MEDIA?

Also, I would pose this question assuming the use of the 2 pot system with water gauge.

It is hard for me to believe that there is much difference between watering with a little bit of water in the pot, or having it be dry a couple days before watering.

One of my primary considerations for s/h was the ability to water ALL plants at the same time, to reduce maintenance and allow plants sitters to be successful.

SJ

[Ray]

Originally Posted by smokinjoe1952

My culture pot supplier (2 pot with gauge) clearly states to let the pots go dry before watering again.

You have stated many times that allowing the pots to go dry is simply using LECA as an alternative media in traditional orchid culture. I'm SO confused.

I am not sure what the solution is, but have a hunch that both methods will work.

My question would be:

WHAT ARE THE ADVANTAGES (in terms of plant health, growth, flowering, etc.) OF S/H, VERSUS USING LECA SIMPLY AS AN ALTERNATIVE MEDIA?

There are actually several advantages to semi-hydroponics over using LECA as a medium in traditional culture.

1. Water is the primary driving force to growth. A plant that has a non-stop supply of water will grow faster than one that dries out between waterings.
2. Constantly-moist medium will not build up mineral salts and plant wastes as rapidly as will any medium that dries out between waterings.
3. Likewise, residues will be flushed more easily out of a medium that stays constantly moist.

Also, I would pose this question assuming the use of the 2 pot system with water gauge.

I am not a fan of such inner/outer/gauge pots for orchids. In general, orchids have evolved to being exposed to very pure (rain) water containing little-to-no dissolved solids. With my modified deli-container design, it is very easy to flood the plants and let them drain, flushing them each time. With the pots you have, the plants either sit in their own wastes for a time, or you have to dump the outer pot, flush the inner pot with medium, then reassemble, which is more effort.

It is hard for me to believe that there is much difference between watering with a little bit of water in the pot, or having it be dry a couple days before watering.

One of my primary considerations for s/h was the ability to water ALL plants at the same time, to reduce maintenance and allow plants sitters to be successful.

If you accept the facts I mentioned above, the difference becomes clearer.

Watering more frequently to flush the pots and keep them wet gives you those advantages and still allows you to do them all at the same time.

There is nothing that says that one culture method is far superior to another, and there is nothing that says that your habits and growing conditions are conducive to all techniques either. I had pretty much any plant you can name in S/H in my greenhouse, but I couldn't grow a simple hard cane dendrobium that way to save my soul!