Starting Catt seedlings in Hydro?
 

I wrote a rather detailed post regarding my de-flasking in the pest and disease because of some black spots/leaf discoloration. However, the roots seem to be strong green/white and healthy so I put them directly into 2" net pots. I put several into pea-sized pre-soaked Hydroton clay pellets ( previously used to grow datil peppers so I thoroughly cleaned & sterilized in a pressure cooker then soaked in 1/4 strength Orchid grow fertilizer, kelp and RO water.) I put several plantlets into pre-soaked rockwool cubes ( in same mixed orchidgrow/kelp RO water) which I gently pulled apart and layed the roots inside then placed into 2' netpot (rockwool was agri supply cubes new from a package). Do you see any issues so far?

Let me just say that I'm new to orchid growing in this way and have some concerns. Although I have experience with Hydroponics systems. (Over the past 5 years I have both built and purchased many hydroponics ( water and nutrient grown) and aqua-ponics systems (water with the growth nutrients from freshwater fish), including building ebb and flow systems using water pumps and air stones, deep-water cultivation using roots above waterline in an air space and airstones to oxygenate, as well as both buying pre-made planters and building many reservoir/self watering systems and self wicking systems for other plants and trees, this is by far my most used as I'm almost exclusively growing my fig trees and gesneriads (african violet family), and herbs in this way.

Most of you orchid growers seem to be using slightly different nomenclature here thus I will attempt to be as specific as I can.

First, I didn't use a reservoir (semi-hydro?) set up on all of these baby Cattelaya's ( I actually have chosen one to try the glass jar/hydroton wicking) but the rest are all within various media described above within 2" net pots. This is so I can control the dry/wet intervals for now and closely monitor until I find the optimum cycle. I can easily drop them into a larger reservoir.

I previously built a deep water one from some former bulk candy refill containers recycled from Ikea's trash (a three quart clear plastic cube with lid in which I cut 2 holes in opposite corners to hold 2" net pots and a small hole to feed the hose for the airstone which I used for oxygenating the nutrient water.) I can reuse these cubes, either with a wick or in the usual deep water method by raising nutrient solution to just cover the bottom layer of hydroton and encouraging the roots to get long enough to dangle through the net pots into a deep water set up as the solution levels fall. As for sharing water right now, the plantlets are all at the same starting point any pestilence is already in their "culture" and most people community pot these at this point anyway.

My biggest question is this, How are people doing with Cattelayas in hydro? I see some people referring to having them in hydro but not many pictures or videos with them blooming in hydro. Also, everyone seems to use hydroton, So Is there an issue I should know about with the rockwool staying too wet? I know in theory if you don't squeeze it, it remains super-porous and allows great oxygen exchange but...it is significantly wet in fact it feels "juicy-wet" after being soaked like loosely packed long-fiber sphagnum moss. I still don't have any time gauge on the speed of evaporation/nutrient uptake to allow the roots to get their "dry period". I'm in humid North Florida too! Does anyone have any experience with the drying timeline here? What do you orchid experts think? Too wet too long? Also, should I have waited for these plantlets to grow larger? I would think agar to hydroponics would be less root adjustment but, I'm not seeing any people claiming success with seedlings in hydro/resevoir/ semi hydro. Is the deep water resevoir a problem? Will the roots rot in deep water, do they stop growing at the waterline, fail to grow multiple roots and just grow one long taproot, or stop midair and turn away? Any info is appreciated!!

From what I have seen and read ------- it works, and there is no problem when it is working. It's a control system balancing act. So for it to work, it's basically all those things you're doing, like having the water oxygenated enough, and free of particular pathogens or disease that can harm orchids, preventing the water from being toxic to the plant, and keeping water at suitable temperatures. The conditions up top need to be considered too - eg. humidity and air circulation. Failing to get things right can negatively impact the plant --- just like if growing plants in regular/traditional styles - except it might be easier for people in general to go wrong with semi-hydroponics style. Just got to keep adequate control of the system.

I personally wouldn't grow most Cattleya any other way but semi-hydroponically. Even my nobilior which "require" a dry rest thrive in s/h. The only reason I used the word "most" is due to recently deflasking some Barkeria spectabilis. As I've watched them start to grow on I realized potting these plants in anything is a waste of time, as they'll just try to climb vertically right out of any pot. But other than that, s/h is the way to go for Cattleya under my conditions.

I am not a fan of hydrophilic rock wool, as the texture is fine enough to be completely saturated with water, which means there can be no air flow within it. It's sphagnum to the extreme that doesn't dry as as fast.

When most folks talk about "hydroponic" orchids, they're referring to "semi-hydroponics" which is simply passive hydroponics and staying constantly moist. If they allow the LECA to dry out, it's really just traditional culture using an inert medium.

You are addressing exactly what I was wondering about! The rockwool I have does seem to dry to a reasonably moist environment after two to three days in the net pot (that is without any additional nutrient solution for wicking) I’m thinking that’s not going to be as convenient as the LECA/reservoir/wicking in a passive setup and possibly not as stable due to the unpredictable fluctuation from completely saturated to almost completely dry. As you noted the use of an inert media and wet dry cycle requiring a manual watering schedule of three days is really no different than using traditional (almost inert) media and harbors the additional risk due to the lowered oxygen exchange when at full saturation. I am however thinking if I see any drying beyond the top layer of LECA due to evaporation, rockwool May make a great topper as it would be expected to have a stronger wicking action due to greater surface contact with “wet” LECA. I anticipate that I will be repotting the rockwool plantlets to LECA shortly. I still am curious as to the possible benefits of a ebb and flow or deep water/oxygenated well/res setup.

---------- Post added at 01:21 AM ---------- Previous post was at 01:19 AM ----------

So, do you allow for a dry rest by emptying or not filling the reservoir?

Nope. I do withhold fertilizer, but water normally.

Ok thanks for the tip!