Why S/H isn't for me and now.

[YetAnotherOrchidNut]

I know a lot of folks on this forum use S/H very successfully. I am one of the people who tried it out and have decided, for now, that I wont be using S/H in my growing conditions, and I wanted to share my general thoughts about my experience.

I want to emphasize that I do NOT have anything *against* S/H. I have some modest experience of using various types of hyrdoponics, mostly active, producing extremely good results for other plants. From my point of view S/H is a just a form of passive hydro using leca (semi-hydro is a misnomer albeit good advertising), which is actually pretty similar to my preferred form of hydro, active-aerated-flow in leca. Only difference is in active flow you would have a reservoir with aerated water which you would flow through the leca using a pump. In the future, when I have a temperature controlled greenhouse I will try to grow orchids in active-flow, and in semi-hydro, but for now I will not.

I live in Amsterdam, and I have my plants on top of boxed in wall heaters in front of my windowsills in a no-AC house, and also in hanging pots. In my home the growing environment varies wildly in terms of day/night temperatures and available light (some of my plants are under lights as well). We peak out at over 16 hours of light in summer and less than 8 in winter. Winter is typical wet and for short period of the season will drop below zero. In the summer it can get up to 30c or more. So even if I set my house thermostat to not drop below 18c, the plants can see wildly varying conditions, at night dropping to 16c or lower near the window, except when the heaters turn on when they can go way up. Humidity in the summer can be high, and in the winter the heaters dry the air out, so it can drop very low.

Several years ago I became aware of the S/H movement, read all the articles, and put a bunch of plants into S/H, including an opportunity to take two keikis from the same plant and put one in bark and one S/H. At first the results seemed really good. It was spring going on summer when i did it and the results were positive, it seemed like the SH plants maybe grew a bit faster, except that contrary to what I expected it was more work to maintain my S/H plants than my non-S/H plants. I use the "long soak" method of watering my bark plants. I mix up fertilizer, fill up the cache pot, let it soak for quite a while, and then dump it. The comparable process for my S/H plants was "flush every time, and then empty and refill the reservoir with fertilized water". Which in practice for me took at least twice as long as what I would do with my bark plants.

But then winter came, and I noticed that the S/H plants werent as happy. In fact of the two keikis I potted the one in S/H rotted out and ultimately died. The others made it out of winter but were clearly behind the other plants. Some of my onicidiums rotted, and I had other issues.

Figuring I was doing something wrong I tweaked the setup a bit. Made new pots with the holes positioned a little differently, etc. I persevered with it for some time, but over time I observed that the phals i had left in bark had grown larger, produced more flowers, where the phals in S/H had dropped their lower leaves and were about the same leaf count after three years as when they started. I also noticed that the oncidiums I had not repotted were much happier. So earlier this year I repotted all my S/H in bark mixtures and after some time to adjust they have responded extremely positively, with massive root growth, new leaves, and etc. The Oncidiums in particular seem to really appreciate the difference and have clearly sped up their growth pattern and are producing much larger spikes.

I have been reflecting on why my experience was what it was, and I think there are two broad reasons, the first is that S/H gave me less options to respond to environmental changes, and the second is that bark is more tolerant of error.

When I say less options what I mean is that with S/H I had two options of media choice, a ball style LECA highly available, or a larger more irregular shaped LECA I could get from an orchid specialist. Other than that I could control the height and breadth of the pot, but I can do that with bark, and actually have more options to do so. With bark media on the other hand I have access to range of wood types and chip sizes, as well as a whole host of amendments like perlite, vermiculite, sphagnum, LECA, peat, etc. If I want to adjust the moisture levels a plant receives I can alter the mix. With S/H and leca there isn't much you can do beyond change the shape of the pot. Even watering more often doesn't really change things, once the reservoir is full its full.

The other thing is that its really easy to source tightly fitting cache pots for bark pots, especially ones where the inner pot "hangs" on the cache pot and does not actually touch the bottom of the cache pot. I found no convenient way to create the same effect with S/H. In fact a recurring problem I had with S/H was the reservoir draining accidentally if the cache pot it was within was moved, and I found no way to hand the S/H pot inside the cache pot. Eg, using S/H as a hanging pot is asking for trouble.

One theory i have about this is the way I mount my bark cache pots, and the use of the bark and other media combines to act as a stabilizing insulating layer around the plants roots that protects it from the colder nights and from the more extreme warm conditions when the heaters turn on. The fact that most of my plants "hang" in their cache pots means that there is an air gap between the inner pot and the media and the outside air. With my S/H plants I usually had them sitting inside of a slightly larger container, thus not creating a sealed environment in the cache pot like my bark pots have. Any temperature drop in the ambient air would be exposed to the entire surface area of the S/H container.

The second part is tolerance to error. My experience with hydroponics is that it is universally less tolerant to error. There are no buffers in the system which will provide some bounceback. For example, bark media as it decomposes turns acidic. Many water supplies are a little basic. Bark media will buffer the effects of the water. With hydroponics systems using LECA this doesn't happen. The fertilizer concentrations and ph levels in a hydroponics system can go through major swings over time just due to evaporation if not carefully monitored and managed. So if you forget to flush your S/H you are probably doing more damage than if you forget to flush your bark. For at least part of the time in question my lifestyle was inconsistent. If I had to go away for a few weeks I wouldn't necessary bother with my plants. This clearly to me affected my S/H plants more than my bark ones.

What I have found is that if you have a busy lifestyle, and cannot be very fastidious about PH adjustments, and fertilizer management, and cannot provide a stable environmental conditions, and in particular if you have to deal with cold weather fluctuation then S/H is going to be much harder to achieve the same results as you will with bark, especially if you have a lot of plants.

This is not an argument that S/H is wrong or that folks should not try S/H, or convert away. If it works for you and it makes you happy then I am happy for you! I fully believe that done properly under the right conditions SH is probably superior to bark. But if you have to grow plants in your living room in a northern environment and have a busy lifestyle then I think S/H is not what I would recommend.

Anyway, I just wanted to share a negative experience with S/H and my thoughts on why it was negative so folks in my situation can make their own decision.