How to tweak S/H conditions to meet plants' needs

[Mr.Fakename]

I've been reading as much as possible about S/H, but there's a piece of information I'm lacking before taking the plunge:

How do you choose your container's shape & size, reservoir size and so on, for each plant?

I want to keep pretty short wet/dry cycles on some plants, but others can stay moist all the time.

Regarding wet/dry cycles, isn't dried LECA going to desiccate roots?

[estación seca]

In S/H the reservoir always remains full. The LECA always remains moist. Neither should ever dry out, or it's not S/H culture. Few orchids really want to dry between watering.

You can water every day, or less frequently if the reservoir stays full. Different plants use different amounts of water. I need to water most Cattleyas in S/H more frequently than most Phals.

Size of container isn't an issue because the medium is well aerated. You can put a seedling into a container appropriate for a mature plant.

Reservoir depth is somewhat arbitrary. Deeper means watering interval can be extended.

[vegetalmatter]

Nothing should dry out in S/H and the wet/dry cycle becomes irrelevant because the medium is both moist and well aerated like ES said. The old root system that is used to the "wet/dry cycle" will likely rot away and the new root system that grows will be tailored to the constantly moist and aerated environment of S/H

I use the same size jar and reservoir size for similar sized cattleyas and phrags for example and they both do equally well.

I can recognize that some plants like more water than others and some have root tips that are more sensitive to the topmost dry layer of leca. I find that shorter jars tend to stay more moist at the top because the water doesn't have to wick that far. Alternatively, drilling holes higher up so that the reservoir is deeper is the same as using a shorter jar.

[Ray]

As had been stated, once a plant has converted its root system to S/H culture, you really don't want it to ever dry out.

Pot diameter is not a particularly sensitive parameter because the LECA wicks well enough that there's not a huge center-to-edge moisture gradient as there is with traditional media.

The reservoir-to-top of LECA distance can be shortened, if need be, to compensate for faster evaporation. I have recently found that throwing some rockwool cubes into the LECA keeps the entire column moist, as the cubes act as small reservoirs throughout the medium, meaning that drilling holes higher is not needed.

By far, the biggest "gotcha" is temperature, as a plant growing well in bark, for example, may suffer under the same conditions if grown in S/H, because the evaporative cooling effect is magnified. Increasing the ambient RH can slow that process, or as many have done, just set the pot on a seedling heat mat, as that 5°-10°C boost is all it takes.

[Mr.Fakename]

Thank you all once more. Your amount of knowledge and eagerness to share it are a treat

S/H seems to have many benefits and the pics of your orchids really speak for it. I can't wait to try it (on a few plants for a test-drive in my conditions, obviously)!

[Ray]

Having invented the technique many years ago, I did a lot of experimentation and found many plants that were easy to grow that way. At first, like many others, I concluded some plants "liked" it while others did not. And then a funny things happened....

As more and more people tried it out, some were very successful with plants I had completely ruled out, while others failed with plants I felt were super easy. Hmmmm.... Lesson learned that "S/H" doesn't completely describe "orchid culture", just water delivery and the use of an inert medium.

Now, I no longer grow plants that way that I once did (phals - my conditions changed when I moved), but all my slippers seem to love it still.

[estación seca]

Listen to Ray. He invented S/H.

[katsucats]

It might not be "S/H", but I'm not always on top of my schedule, so for me the reservoir does dry out sometimes, or at least very close to drying out. It might even work better for some plants (e.g. Encyclia). Although the reservoir should be theoretically "always full" under S/H, unless you water daily, there is a cycle as the water is absorbed/evaporates.

Since there is clearly a whole philosophy behind S/H, I wish there's a term that we could use that deals with growing in inert media with broader definition than S/H. Water culture folks like to insist that it's only WC if there's no media. Makes no sense to me, but I don't want to co-opt anyone's movement, either WC or S/H, if I'm not strictly adhering to either.

[Mr.Fakename]

Originally Posted by Ray

Now, I no longer grow plants that way that I once did (phals - my conditions changed when I moved), but all my slippers seem to love it still.

Funny you mention that Ray.

While browsing for info, I read that about you:

Did You Know: the inventor of the semihydroponic orchid method, doesn’t grow his phals in semihydro? It’s true. His phals are potted in sphagnum moss.
(The Down Side to Semi Hydro (S/H) and Full Water Culture (FWC) for Orchid Care >> Here But Not)


Since we're on the topic of Phal, do y'all mind sharing pics of yours please?
I read a comment from ES about Phal thriving like nobody's business in S/H, and that's what my dreams are made of.

Originally Posted by katsucats

It might even work better for some plants (e.g. Encyclia)

I don't grow those but if I do one day I'll remember that, thanks for the tip!

[estación seca]

Phals are warm to hot growers. They grow wildly in S/H in warm to hot temperatures. Cool dry conditions, like in most heated houses in cold-winter climates, are not good for Phals. There can be substantial evaporative cooling of the medium in S/H with low ambient humidity. This is not good for hot-growing plants.

People disagree with me but I think Phals are marginal unless you can keep them much warmer in winter than most people keep their houses. People do manage to keep them alive and flower them in these conditions.

I've never been to Ray's house. His current outdoor summers are probably ideal for Phals in S/H. But his winters indoors with central heating probably are not.

Various OB members over the years have shown excellent Phal growth with heat mats in winter. This solves much of the problem. I have a sunroom with warm to hot winter days. Phals do so well for me in S/H I don't grow them any other way.