Now you can take your mouth off the fire hose.

From my reading so far, I think Ray's explaination answers the question, especially that the velamen traps any particulates immediately, within seconds. It is almost like tissue paper in that sense. The particulates are in the water as a result of ions. In rain clouds, the first few seconds of rain usually bring the bulk of suspended particles down into the "tree canopy" and that is when the bulk of the feeding occurs.

To water with "pure" water (meaning no fertilizer) is to saturate the velamen, and pretty much waste the rest of the water. The pure water flushing is to get rid of salt buildup. Rain water does not have this, only ground water, where most of our tap water comes from. Orchids lucky enough to be raised with only rain water, or the water coming off the trunks of trees, generally do not have this problem.

Having filtered water is helpful.

There are many reasons why things that are common and successful practices on a commercial scale in a greenhouse environment might not be the best or only choice for a few plants on the windowsill grower. Done right, the water first then fertilize method wastes much less fertilizer, an important consideration in a large scale for profit operation. Certainly it can be successful on a small scale too, but that doesn't mean it is the most convenient, time effective, fool-proof choice for a private collection.

When I was learning about orchids in the public greenhouses in Piedmont Park - now the Atlanta Botanical Garden - some 40+ years ago, it was common practice to water, then feed, but the concentration of fertilizer applied was many, many times the concentration we commonly use today, and orders of magnitude stronger than the plants would see in nature.

Just because "we've always done it this way" does not mean it is best. In fact, more often than not, it isn't.

Interesting discussion! Thanks for all the info, experts.

Ray, S/H clarification if possible. Since switching to S/H, I have been 'flushing' my plants with plain water each week with my kitchen tap's spray function which produces lots of bubbles of air as the water rushes through the media (we have excellent soft water here). The more 'touchy' plants that would prefer rain water receive tap water that has been sitting in a bucket for several days to allow the chlorine to dissipate (since I'm in a condo, rainwater is difficult to get). Once that's done, I drain and fill the reservoir with fertilized water solution. I did this to prevent salt buildup in the media, but perhaps I misinterpreted your S/H care instructions.

Is the weekly flushing 'overkill'? Am I preventing my plants from receiving the nutrients they need by using this method? Or does the airy S/H media allow the root velamen to dry enough to absorb the weekly nutrients?

Wow.

Re: S/H Clarification:

For an apartment environment, I think that's a pretty good technique. In the greenhouse, I just flush heavily with the dilute fertilizer solution, allowing the excess to dump on the floor.

In a S/H pot, the roots should never dry out. They will actually not grow as much velamen, as they don't need it to trap and hold nutrients, as they're always available.

Ray - For you it may not be cult, but believe me, some people have apparently been drinking the k-lite. (That's a metaphor, folks. Do not drink your k-lite.)

Of course, yes, that makes sense. Thank you!

Haha! Agreed. Us orchidists, it seems, tend to want whatever magic potion we can get to provide us with the perfect plants. So many tend to think the magic comes from just one thing rather than simply providing the proper care. Or more honestly, as someone here wrote once, NOT getting in the way of the plants' natural ability to survive and thrive.

I don't mind it being called a cult, because I am getting very good results, but if anyone suggests going to an orchid festival in Jonestown Guyana, and Purple Kool aid is on the menu, count me out.