True Hydroponics

[sailor]

Is anyone aware of private or commercial growers using true hydroponics for orchids? I am currently building an ebb and flow system for garden veggies and would like to try a few small plants that have recently been converted to S/H.

Seems like it could have huge potential for quickly taking plants from compot to blooming size for the retail market. I could also see it as a technique to rapid start plants when converting from traditional media to S/H. Or as a nursery for S/H plants that have stalled until their root systems have adapted.

[Mahon]

I personally haven't heard about hydroponics with orchids... I think it may be difficult due to specific requirements, and most orchids need to dry out some. The ones that don't usually dry out (like most Pleurothallids and other high elevation tropical species) would need correct temperatures... I personally would also find hydroponics for orchids somewhat impracticle... and growing from compot and placing in hydroponics probably wouldn't survive, just a gut feeling.

Also, transplanting explants or seedlings into media after hydroponically growing may prove difficult. The plants needs all the roots it can get, and it most likely will attatch itself pretty good.

Perhaps a similar hydroponic method is to let the plants get water when they want, which would be a container in a container, with a certain water level (that automatically drains out through a hole), and the roots can go through small rock into the water resevoir below, with airspace in between the containers... similar to s/h, but using smaller rocks (quartz chips)... with these containers, algae will most likely grow, which could be benificial for the plants.

-Pat

[Ray]

1) Pretty much all orchid growing is hydroponic, as the plants use the medium for mechanical support and do not get their nutrition from it, instead taking it from the nutrient solutions we use.

2) Most growers will tell you that having a common nutrient bath for multiple plants is a bad idea, as it becomes an excellent vector for the spreading of pathogens - fungi, bacteria and viruses. No commercial orchid grower is going to assume that level of risk with his livelihood.

3) You are correct on the faster, better growth though. Having a constant supply of water and nutrition always beats an intermittent supply, and - all else being correct - gives the plant the best opportunity for growth and blooming.

[Mahon]

Originally Posted by Ray

1) Pretty much all orchid growing is hydroponic, as the plants use the medium for mechanical support and do not get their nutrition from it, instead taking it from the nutrient solutions we use.

Isn't this a pretty hard statement to say though? Humus, peat moss, and rocks (to name a few) naturally contain minerals or nutrients that are absorbed by orchid roots. Addition of specific limestones mixed among media will also be utilized by the plants. These plants can survive without additional supplements and nutrient solutions.

That would also mean that your semi-hydroponics is technically hydroponics...

Originally Posted by Ray

3) You are correct on the faster, better growth though. Having a constant supply of water and nutrition always beats an intermittent supply, and - all else being correct - gives the plant the best opportunity for growth and blooming.

Wouldn't a constant supply of water induce rotting, growth of bacteria and fungi, or even death in most orchids? There are some orchids which are tolerant of constant amounts of available water, but some cannot stand to have their roots wet at all times (ex.- 'overwatering')...

Just a suggestion; how about using only red and blue lighting for the plants to induce growing and blooming? Or what about blue and red LED lighting (which would eliminate the problem of heat produced by typical lighting)...

-Pat

[Ray]

Pat, while I'll agree that plants do absorb minerals from stuff like decomposing humus in nature, the solubility of rocks is insignificant. In the case of an epiphyte high in a tree, the vast majority of the nutrition comes from the nuitrient-rich "wash" coming from the forest canopy after a rainstorm. Besides, once we "domesticate" plants in pots, the supply of decomposition products is basically nil, unless you let the medium get so far gone that you risk suffocation and root rot.

As the the limestone addition, one must be careful, as relying on natural solubility is risky. You're much better off adding it in a controlled solution. FWIW, I have also heard scientists discussing the question of "does that limestone dissolve to add nutrients, or it its presence merely a pH modifier, changing the solubility of other minerals?"

As to the constant water supply being the cause of root rot, I believe it is a myth based upon incomplete analysis of "what's going on" in the pot. The fact that has lived throughout the years is no indication of its validity. Orchids can and do grow fine with their roots totally submerged - IF they grew that way. Submerge roots that grew while in another environment and they will suffocate, die and rot. Bacteria and fungi may have rotted the roots, but it only happened after they were dead or severely compromised by the stress of suffocation.

[Ray]

Adding to my earlier response Pat, I fully recognize that semi-hydroponics is true hydroponics. The moniker was coined to differentiate it from the large, single-nutrient bath, lots-of-equipment types, and nothing more.

Looking back at your original response to "sailor", one of the reasons that there are difficulties moving plants out of hydroponic culture into other methods using traditional media relates to the tailoring of root cells I mentioned previously. Once established and growing in hydroculture, the roots that grew in that environment are optimized for those conditions. Move them into other conditions and they won't work as well, and depending upon how large of a difference that is, might not work at all and you'll get rapid decline of the existing roots. That's the reason that repotting should always coincide with new root growth - the new roots will be tailored to the new conditions, whatever they are, so will support the plant while the old roots become less effective.

The last paragraph of my last response agrees with your assessment that moving a compot into hydroculture could be a problem, for the same reason - the roots grown in the compot are not structured correctly for hydroculture, just as roots grown in hydroculture and not structured right for other conditions.

Move that flask of seedlings directly into a hydroculture compot, and all is well. I've done so many times.

[adriponic]

Hello Sailor

Any culture without SOIL is termed Hydroponics, be
it sand, culture, cocopeat, clay or even without substrate.
Looking at it this way, orchid in a medium of say bark + perlite + spagnum + whatever but without SOIL is Hydroponics. Provided nutrients are applied in aqueous
solutions of any formula and concentration.

To answer your question, I say yes, massive culture of
anthuriums, orchids, curcumas, globas etc from in vitro
plantlets through hardening until blooming size is carried
out here in Mauritius. It all started in mid 2002 when I
was appointed consultant to the biggest grower and
exporter here.

We are using ebb & flow tables for the Research work
prior to commercial implementation. Commercial growing
is carried out in inclined channels (3%) 15 meters long
by 0.6 metres wide. Nutrient is recirculated for 15 mins -3 to 7 times each day depending on the season and size of plants.

We have not experienced more mortality compared to the older method of growing, but the time from out of flask to blooming size has been halved.

JP