Hydroponics vs Semi Hydroponics - Orchid Board

Sandy4453 · #1 10-18-2007, 07:44 AM

Good morning everyone!

Is there an advantage to straight hydroponics vs. semi hydroponics and visa versa?

I've been using Hydroton both ways, for straight hydro and s/h. I planted a paph in straight hydro but algae forming in less than 2 weeks, seemed to be a problem. Without removing the plant and cleaning the container (glass), I wasn't able to flush it out or control it. It's now in s/h where I can flush it if this occurs again. I use worm tea (2-3 oz. per gallon) on all of my orchids including s/h and seaweed additive to all (except the s/h).

I was told that root rot would never occur in straight hydro (water & air required for rot thus, eliminated in straight hydro).

When potting in s/h, is it necessary to make sure that the roots don't reach the standing water at the bottom? (I have mine in a plastic container with holes on the sides.)

Also, should I be fertilizing or is the worm tea enough?

These questions have most probably been answered already here so please excuse my laziness in not searching further.

FinnBar · #2 10-18-2007, 08:30 AM

Hello there,
I think old roots will eventually disintegrate in S/H whether in water or not. My advice would still be leaving them above the reservoir while repotting.
I'm curious about your straight hydroponic setup, could you elaborate on that a little?

Sandy4453 · #3 10-18-2007, 08:51 AM

Hi FinnBar. Thanks for your response.

Straight hydro requires less to actually explain. There's no reservoir, no holes in the container. Water filled to the top and you can either let evaporation occur till there's approx. 1" left of standing water or continue to keep it filled.....so I've read with this method. The negative I found in this was the rotting odor and the algae accumulation.

Sandy4453 · #4 10-18-2007, 12:10 PM

*****bumping up*****

quiltergal · #5 10-18-2007, 01:16 PM

That's not my understanding of how straight hydroponics works. There is a reservoir but it is cycled up to the top of the pot by a pump and allowed to trickle down through the hydroton. The water contains nutrients that need to be tested and refreshed weekly. So say you have a 5 gal bucket filled with hydroton & plant. The bottom third would be filled with water and nutrient. There is usually a circular sprinkling device at the top of the pot that drips the water from the bottom onto the hydroton at the top of the pot. Roots in standing water to the top of the pot will rot. That's probably what smells.

Personally I think s/h is much easier to manage that full hydro.

cb977 · #6 10-18-2007, 01:55 PM

Here's an OB Member article on Semi-Hydroponics:
http://www.orchidboard.com/node/77

and here's some info on Hydroponics:
Common Hydroponics Questions - GTG Hydroponics

markr · #7 10-18-2007, 07:39 PM

SRF, what you have described seems to be another variant on passive hydroponics ('semi-hydro' as it's known around here, I'm more familiar with the term 'hydroculture').
"True" hydroponics, as others have mentioned, involves a circulating water supply (with pumps etc.) and very careful management of water chemistry (oxygen content, pH, minerals, etc.).

I'd like to hear more about your system though - if I understand your description, it sounds like you are growing orchids in containers of water which you keep continuously topped up? Are the roots continually submerged? If so, it surprises me that this works and that you haven't lost any roots to suffocation.

By the way, the information you were told about roots not rotting is incorrect. Root death is not (usually) caused by rot, rather roots rot after they have died - they usually die from suffocation or salt/precipitate build up so the idea that rot can't occur on submerged roots is really beside the point, along with being completely untrue.

Sandy4453 · #8 10-19-2007, 09:46 AM

Thank you all so much for your replies.

markr, I'm glad you responded here. What you've said makes more sense to me than the surprise I felt by the suggestion to try growing the way I described. Thankfully, this method I mentioned was quickly squashed and was only tried on one paph. I had been following a thread on another forum where everything I described was suggested from a Fl. orchid grower who grows all his paphs in LECA filled with water in containers with no holes! I'm aware that rot is followed by root death first and am thankful I didn't lose any roots in the almost 2 weeks I had the plant in these conditions, speaking of surprises. I now have this paph in s/h. This grower 'swears' by the method I described.

quiltergal, I'm with you...s/h is much easier.

cb977, I've been reading these threads you linked here. Thanks much!

One more thing. I've been reading a lot lately about disastrous results people are having with phals and s/h, it seems to be the hot topic, all of a sudden. Aside from washing and soaking the LECA (Hydroton, in particular), I've read that fertilizer containing urea based nitrogen will kill the roots on paphs. Any thoughts on this?

quiltergal · #9 10-19-2007, 01:11 PM

I think urea based fertilizer makes the nitrogen unavailable to the plant. So maybe what's happening is the plant starves to death??

FinnBar · #10 10-19-2007, 02:27 PM

before urea is accessible to plants it needs to be broken down by bacteria.
organic potting media hosts a good ground for this bacteria to grow in whereas in inert media this useful bacteria doesn't exist. "straight" urea can easily burn roots.
I would imagine this wouldn't apply to Paphs only. then again, I don't know what's the case with Paphs. growing in organic media. I believe they should be alright but maybe someone here can confirm this..?