Epiphytes versus terrestrials

[terryros]

I am 5 months into S/H with a 50 plant mixed collection of Catts, Phals, Paphs, Phrags, and a couple of Oncidiae intergenerics. I haven't killed anything yet and have bloomed some things. However, we never run out of questions. This is a basic question about differences in watering and aeration in different types of orchids:

Facts (maybe): The roots of epiphytes and terrestrials are different. When plants move into S/H the plants must adapt and create different kinds of roots and many of the old roots may die. Different types of root cells develop.

Questions: During and after the adaptation to S/H, do epiphytes overall still need drier conditions at the roots than terrestrials or do they become mostly even and you can treat everything the same? Or, would you optimally let the S/H epiphyte go longer between waterings (letting the water/fertilizer solution in the reservoir go almost dry) compared to a terrestrial that you might water frequently and keep always topped off?

[Ray]

I grow both, and if anything, I find that the terrestrials can go longer between waterings than can the epiphytes. In my greenhouse, they all get watered the same. For the tropical houseplants in my home, they go a LOT longer between waterings (because I forget about them).

Assuming you transplant at the correct time (when little nubs of roots are just beginning to grow), the best thing to do is to water as you will on a regular basis. Doing so allows those new roots to grow adapted to the new "normal" conditions. If, at first, you keep the plant drier than you will routinely do in the future, the plant will grow roots tailored to that environment, which means they may not be ideal for the "routine" one you eventually go to.

Also, you must keep in mind that the solution in the reservoir changes chemistry fairly quickly as a result of the differential extraction of individual nutrient ions by the plant, its excretion of compensating ions, and gas exchange. That means that you're better off watering more frequently, so that the pot chemistry remains more stable, and closer to what you intend.

[terryros]

Thank you very much. It makes sense to me. I have all pots in 7 inch saucers that I fill to the 1 inch mark with solution. I have been filling these back up when they get half way down. Every two weeks I flush all pots at a sink to reduce build up and then fill them up with RO water with fertilizer. I think I have goofed by drilling additional aeration holes around my pots but I think you believe that this may cause evaporation which is faster than anything can wick up and that aeration comes well enough from the top any way?

I think you vart the style of pot that you use for the different genera (the taller versus the shorter/wider?

[Ray]

Yes, extra holes can accelerate the evaporation, negating - maybe overcoming is a better word - the wicking.

I use taller profile pots for paphs, cymbs, catts, and squatter ones for phals. Most other genera, I grab what's handy. Frankly, in my very humid greenhouse, the evaporation rate is very low, so it hardly matters anyway.

[terryros]

Thanks. I am switching out of my pots with the drilled extra holes to stop working against the wicking. Hate to ask the rationale for the taller pots versus the shorter for the different genera?

[Ray]

My experience with paphs and cymbs in pots seemed to suggest that they like to drive their roots deep. With phals, I was shortening the reservoir-to-top of medium distance in order to reduce the moisture gradient in the medium. Since then, I also give phals very large diameter pots (relative to their size), as I find that they sink their aerial roots into the medium that way, better stabilizing the plant mechanically.