Breaking the rules?

[orchidphile]

Hi, everyone.

I've been using semi-hydro with great success. I recently watched a YouTube video of a presentation by Thomas Voytilla, given to the Tip of Texas Orchid Society. This gentleman grows a lot of orchids in semi-hydro, with great results, and said he doesn't use the flooding method to water--he just tops off his reservoirs and says it works fine. If I remember correctly, it was also this video that said flushing with plain water isn't necessary either. He's apparently been doing neither and getting away with it for years. Is it possible that semi-hydro can be even easier than we already thought?

[WaterWitchin]

Well, it may work for him and his particular culture and climate and orchids he grows that way. It wouldn't work for me, as I've tried it quite a few years back. Build up of salts on ones I don't use R/O or pond water on. Build up of "mush" in reservoir of root debris as they transitioned.

Wonder if he fertilizes? I would be concerned about a build up over time in my culture, even though I don't fertilize often.

What works for one "might" work for another. Depends on a lot of other factors... and mine don't suit it.

[Subrosa]

Many people have difficulty discerning the difference between proving something and getting away with something.

[Ray]

Tom learned about S/H from me, during a presentation I gave to an orchid society in Virginia, and he has apparently changed what I taught him. Here's why I disagree with that approach, but why some might get away with it, at least for a while:

In a semi-hydro pot, the vast majority of the evaporation occurs in the top portion of the column of medium, in a gradient, of course.

As the water evaporates, dissolved solids in the liquid - fertilizer nutrients, whatever was in the water, and plant wastes - reach their maximum solubility levels and precipitate.

If you water properly, which means frequently flooding the pot to the top with nutrient solution and letting it drain, you flush the pot, mostly redissolve those residues, saturate the medium, and refresh the chemistry of the solution in the reservoir.

If you only top up the reservoir, that evaporation/precipitation process continues unabated, allowing the residues to accumulate to the point of being toxic to the plant.

Now some caveats to that:

If your growing environment has very high humidity, the wicking ability of the LECA outstrips the evaporation rate, so the top stays wet, and precipitation is kept to a minimum. While the "Flush At Every Watering" (FAEW) technique is still preferred, it is far less crucial to the long-term health of the plants.

Likewise, if you sell that plant before the buildup becomes an issue, "it's never a problem" (to you), and if you dump the old LECA when you repot the plant - something I don't bother with because I water correctly - you're dumping the precipitates, too.

[Leafmite]

Claims like this are why it is always wise to follow one's own path when growing plants. I grew orchids with no trouble at all for many years until I discovered online information. Then I thought I could grow better if I followed online advice. Yeah, now I have learned to do what works for me after researching the climates of the native environment and growing habits of my plants' ancestors.

My feelings about this is that it is possible he is not having any issues because he might be getting lucky with chemistry. Water quality can be very different from place to place. Rain tends to bring with it anything that is in the air and tap water brings whatever is in the lake, river, or 'well'. Still, I think his luck will eventually fail.

I highly recommend flushing not only orchids in S/H but the soil-based plants, too, as it keeps them healthy. Plants that are not flushed periodically will usually fail to thrive after a time due to various unused minerals/nutrients becoming unbalanced and, if there is even a tiny trace of salt, it will surely become toxic in time. Flushing allows one to restore the balance in a plant's medium.