I just put Den. Aggregatum in S/H, is that a bad idea?

[Fairorchids]

Originally Posted by Ray

Actually, lots of folks with experience growing plants that need a "winter rest" in S/H (I don't grow them) have proven the "zero water" thing not to be the case at all.

The key is zero nutrients, not zero water.

If you think about the plants in nature, they only get fed when it rains, and they get fed whenever it rains. Those plants typically have dry seasons, when there is no rain, hence no food. it's pretty obvious to the observer that there is no rain, but the "no food" part is easy to miss.

Yes, withholding water can be done is S/H culture, but it's not necessary, as long as you use nutrient-free water.

In my opinion Den aggregatum is a special case. In my dad's commercial nursery this species was given zero water from Oct to Jan, and watered like Cattleyas the rest of the year. They grew, and flowered, fine under those conditions.

I tried the water/no feed approach in 2012/2013. No flowers.

In 2013/2014 I placed it high and bright, and gave it zero water. Two large spikes. And, plant did not get desiccated by that treatment.

[mtorchid]

Assume by "no water" you mean no additional water beyond what your "commercial nursery" provides with ideal humidity levels. In nature, even during dry periods, there is still a substantial amount of dew available to orchids so that has to be provided somehow, either through a perfect growing environment, or for most people who are home growers via minimal watering and or misting. Orchids don't change into cacti during their "winter rest" ;-)

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[BettyE]

Originally Posted by Fairorchids

I have never grown SH, so can't say whether this will work or not. However, this Den needs 90-120 days of ZERO water, cooler temps & bright light from Oct-Jan (or till buds appear). Is that doable in SH?

Ask Ray...he's the person who knows...BettyE.

[mtorchid]

P.S. re "zero water", here's a basic Dewpoint graph. Even with a low level of humidity (20%, the red colored line) moisture in the air will condense into liquid water at around 55 degrees. It's not a monsoon, but apparently enough to keep wild orchids (Dens in this case) alive during the winter months.

[Ray]

Originally Posted by BettyE

I started putting my orchids in S/H, or whatever it is called that Ray sells. I use the course & all of my orchids are doing great! I orginally did this because I'm lazy, & HATE to re-pot. Now, it is sooooooooo much easier. I have about 75 orchids, and all but five are in those brown round balls. ( S/H ) At the end of the Summer, all 75 will be finished! BettyE

Betty, I have to slap you on the wrist for not doing your homework.

Semi-hydroponics is the method of growing plants in single pots, using an inert medium, with a constant nutrient/water supply. It is NOT the medium!

The medium of choice is a lightweight expanded clay aggregate (LECA), and it is available in several brands.

It is also possible to grow in LECA without the reservoir of liquid, and that is just traditional culture using an inert medium.

And I am NOT the one to ask about dendrobiums. I do not have a single one in my collection.

[BettyE]

In answer to that " slap on the wrist," I have to say that it's because I'm lazy that I changed to LECA...and for no other reason! However, I DID get an added bonus...the orchids do like it a lot better, & are growing/blooming like crazy! It's also much easier to re-pot ( which I hate to do! ) So...it's a win/win situation for me. BettyE

[Fairorchids]

Originally Posted by mtorchid

P.S. re "zero water", here's a basic Dewpoint graph. Even with a low level of humidity (20%, the red colored line) moisture in the air will condense into liquid water at around 55 degrees. It's not a monsoon, but apparently enough to keep wild orchids (Dens in this case) alive during the winter months.

If there is enough moisture in air, yes, condensation can form. However, most greenhouse thermostats are set at 55F or higher.

What I meant is 'no watering of the plant, from Oct 1st thru Jan (or till buds appear)'.

This Dendrobium does not become desiccated by this treatment, as it evolved in an environment with this weather pattern.

[mtorchid]

Originally Posted by Fairorchids

This Dendrobium does not become desiccated by this treatment, as it evolved in an environment with this weather pattern.

Den. aggregatum is from areas around N.E. India, which is not a desert. It needs some moisture during the winter dry period to survive. Even at low Relative Humidity (20%) dew/fog would form around 55 degrees at night giving it the moisture it needs to survive until the monsoonal season returns. In your greenhouse I have to assume it is getting the water it needs from high humidity levels. Since high RH is not achievable (or desirable) in most homes, the need to mist and or add small amounts of water occasionally is necessary to keep the orchid alive until buds start to form.

[Berrybee]

Observation at 3 weeks after i put Den. Aggregatum in S/H:
The plant seems to stop growing, and there's always mold on the roots exposed in the air (due to the way the roots growed, i cannot bury all the roots in LECA.) Before I transfered the plant, it grew fast with new shoots and roots. But I haven't seen much growth during the past 3 weeks. Didn't see the plant deteriorating either.

Is this normal or something to be concerned, indicating something is not quite right?
Could it be that the plant was traumatized by being ripped off medium from the roots or by the new wet enviroment? If it is because of the trauma, normally how long will it take for the plant to come back?

The onc. sharry baby type I put in S/H, on the other hand, is happy and growing a lot.

Thanks for any insight in advance!

[mtorchid]

Mold on the exposed (aerial) roots? I've never heard of that. What humidity level is it growing in? If you were trying to force aerial roots into the LECA, that would cause some additional trauma besides just repotting. How wet are you keeping the "new wet environment"?