Switching to Semi-Hydro: a repotting pictorial

[Cewal]

Thanks, Cindi. I'm anxious to try SH.

[Dorsetman]

If I may join in...I got into this area in 1996 ; I moved house, moved my orchids - maybe a couple of thousand into my brand new house, and started to watch them die...well, too many of them anyway. So I took a couple of hundred plants and repotted them into 3 or 4 different kinds of compost, one of which was straight Perlite, to see if any one (compost) was better than the other. The problem with Perlite was keeping it wet - at that time I was using it from the sack, without any pre-soak. The plants in that did the worst - over the first weeks, so I tried placing half of them in a tray of water, an inch or less deep ; then I found that if I put a top dressing of ordinary horticultural grit on top, it kept the perlite in place ; within six months I had transferred all of this lot of 50 into this system, and in the next year went on to move another 1000 into it . ( I didn't use it for my Paphs or cymbidiums, or Vandas ( then - but did experiment with these later, when I was getting fantastic results with oncidiums etc ), and I didn't grow many cattleyas at that time. So it was all kinds of oncidiums and other orchids which could be generally classed as South American thin-leaved - Odonts, Oncids, multi-generic hybrids in the Oncid group, Zygos, etc etc.
I did some research on different materials for the compost ; it must be inorganic, so that there is no rot or decay of the compost itself. I made columns, and measured the rate of movement of the water upwardly ( it's capillary attraction of course - so it depends on all kinds of things I can't measure easily - like the electro-chemical series position of the material , grain size,particle shape, (effectively) surface roughness and so on. But I ended up with the recipe: use coarse Perlite ; wash it well to get rid of all dust and fines, pre-soak before use.
Ordinary pots are fine , no extra holes needed - I can see the fun in destroying one Tupperware container, but I wouldn't want to buy pots at that price for a thousand plants !
Best time to put into the system is the same as the best time to pot anything - when new roots are just appearing , that way they will adapt to the different media.Existing roots will rot - at least the end down in the water will, but new roots which grow into the 3ater don't rot. A friend who took samples of my roots said that under a lowish power microscope he could tell which roots had grown in my aquaculture and which had grown in ordinary ( water when the plant is dry) culture - the root structure is different.
I could write a lot more - but about 2003 I wrote ( by request) an article for a French (language) Orchid journal - I have lost the original, but stumbled across a link to an edited version of the English original recently - it contains some decent pictures too - here's the URL - Hydroponics.
By the way I do have a bee in my bonnet about the names used for these kind of cultures . Hydroponics merely means growing without soil . Who does use soil ? a few people growing terrestrials maybe, but not "mainstream" epiphyte growers. And why semi ? Which is why I have at times used the words Hydroculture or Aquaculture ; sorry -I'm a pedant with words ( comes from my working life - now long past, but incurably embedded).

[Cewal]

Geoff, Welcome and thanks for the link to your article. It was very informative, as was your above post about your experiments, and I enjoyed reading it. Would love to see pictures of your setup. I'm new to this type of orchid growing. I do question your definition of the word hydroponics, though. I thought that 'hydro' was translated into English from Latin and Greek words that, in some round-about way, mean 'water'. Most definitions of hydroponic don't just say that dirt isn't used, but that some type of solution is used instead of dirt. The semi, IMHO, just means that the roots are not being continuously immersed in, or flushed with, whatever solution is being used to provide nutrition to the plant.

[Kmac]

Geoff--

As for the wording...yes, hydroponics (& S/H) don't always seem to be used exactly the same way. I was under the impression that since it comes from the Greek hydros that it always meant growing in water, (and semi for growing partially in water), but it seems thats not always the case & it gets used various ways. At the moment all the orchid genus name changes are more taxing to me than this one though! And S/H is an easy abbreviation, so I will keep using for now.

That is fascinating about the micro differences in root structure. I am planning to report a few intergenerics into S/H soon. I have also been told it would be good for a phaius..any thoughts there?

I will check out your article when I have a spare moment...thanks for posting it!

Kathi

[Noele]

This is a PERFECT article for me right now. I just bought a large bag of Hydroton. This was in preparation for re-potting my cattleyas, because they desparately need separating. They're still blooming and was waiting until the appropriate time for separating them. The Tupperware or Rubbermaid containers make me think of some of those multipack containers at the dollar type stores. This forum is great!

[Breighz]

Thank you for this post! I need visuals too. The media- could one use lava rock that is in the filtration system of one's koi pond?

[ksriramkumar]

Hi Louis,

Fantastic illustration.

I have an observation ...from what i can see, there are multiple holes in the sides of container which would increase the evaporation rate and if it is higher than the wicking rate then the medium could dry out soon..wicking rate is dependent on the material used and could be different for different sizes of LECA and could be different for even different makers.

from what i understand, we just need 2 holes as close as possible so that we de-risk the LECA blocking the holes.

[raybark]

This is the first time I have seen this thread, and as I'm the guy that developed the technique for orchid growing and named it "semi-"hydroponics, I feel that the thread is full of a lot of good information and some that's not-so-good.

LECA is the best medium to use, and it is best to use one that is not totally spherical, but still smooth. Think "egg-shaped". The more uniform the particle size, the better. 8-16 mm is most of what's available out there, and it's fine for pretty much anything. There are variations between brands, but I don't view that as super-critical, unless yours has super-coarse pores, in which case, it will float and not wick well.

Drill (don't melt - fumes) two 1/4" (6mm) holes in the sidewall - as close as you can without having them intersect - about 1"-1.5" (25-35mm) up from the bottom. No more (too much evaporation which defeats the wicking), and no bigger (makes it hard to fill the pot rapidly).

Roots do not "transition" to S/H culture. Once they have grown, they cannot change, and roots that grew in a dry environment will suffer in S/H culture and die. That's why it is important to move a plant into S/H just as new roots are emerging. They will tailor themselves to the new environment as they grow, and support the plant. The old roots will die.

[Dorsetman]

This is the first time I have seen this thread, and as I'm the guy that developed the technique for orchid growing and named it "semi-"hydroponics, e.

So you have been doing it longer than me then, and I started in 1996 ! I gave talks on it to most of the UK orchid societies , at least to those south of Sheffield at various dates up to about 2004 , also gave detailed instructions and lots of pictures in my personal web-site which went on-line in 1998 - -and continued, being updated monthly until about 2005, by which time it had well over a thousand images, and it got beyond what could be done on a free domain, so I gave up.
You could read my posting in this thread some 3 years ago....

I do look forward to your next posting !

[raybark]

I've been growing orchids since 1973, and for me, the issue was keeping my plants alive when I wasn't around. I work in the chemical industry, and from the Spring of 1981 through Fall of 1984, I averaged just under 13 flights a week around North America - I was only home 9 days the whole time my wife was pregneant with our son (don't you know that made me really popular....) - then my territory expanded to North-, Central-, & South America, Japan and China, (with Australia and Europe thrown in now and then) and while I did not travel as often, it tended to be away for a month at a time when I did.

I needed to automate watering, but that's hard to do with traditional media, and leads to rapid root rot unless you pay close attention - another thing you cannot do when you're not there.

The self-draining pot with a reservoir was the first invention, and I started with coarse spongerock (18-25 mm perlite) as the medium, but it crumbled and became a suffocating sludge in the pot. I later moved to 50/50 spongerock/charcoal, pumice, turface, expanded shale, Aliflor - you name it - and finally in 1990-91, Dave Neal pointed me to a guy importing some good quality LECA from Holland, and "the rest is history", as they say.

I'd say one of the greatest ancillary benefits of my experimentation with Semi-Hydroponics is that it has taught me to logically and scientifically challenge pretty much all of the traditional aspects of orchid growing, allowing me to be a better grower - even if it's NOT in S/H.