Inorganic Media ONLY

[Ray]

Originally Posted by Shadeflower

No inorganic does not require more fertilizer.
Barroot plants do not require more fertilizer either.

Agreed 100%

Bark does degrade and does release nutrients but it's not something we should rely on for nutrients

Yes, and think about the fact that to release nutrients, organic media must significantly decompose, and when that happens, it tends to suffocate the roots.

...feeding orchids a lot is less important. One big feed will last them a whole month.

Yes and no. A more frequent, but more dilute feeding regimen mimics nature better, so is bound to be better for the plant.

But inorganic cannot store nutrients as well as bark.

I disagree. For the most part, inorganic media like LECA, pumice, perlite, rock wool, etc., tend to store more liquid than does bark, and it is only when the mineral ions are in solution that it is available for the plants to take up.

The downside to inorganic not being able to store nutrients or buffer the feed water in the pots means you do need to make up a lot more fertilized water and you do need to adjust the ph more.

First of all, water is the driving force for growth, so being able to water more is a benefit. Secondly, adjusting the pH of the applied solution is of far less value than people seem to think. The plant itself, the microbes living in the pot and plant, and media have far greater control over the rhizosphere pH than does the applied solution. ("Inorganic" does not necessarily mean "chemically inert".)

[DirtyCoconuts]

One other factor to remember is environmental

It rains a lot here. I would not be able to keep my plants alive if they all had medium that could over absorb water and suffocate them. I NEED to know that even a torrential rainfall won’t drown my plants

[Ray]

Water absorption is really not the issue.

When we water, most pours right through. Some is immediately absorbed by the potting medium and the plant, but there is a third fractions that is (figuratively and literally) the killer - the water that is held in-between the particles by surface tension.

If those void spaces are small, they can be completely filled, blocking the gas exchange pathways, but if they are relatively large, or the medium can suck away the water, they stay open.

[estación seca]

Remember that growing epiphytes with roots stuffed into a pot is profoundly unnatural. No epiphyte requires medium surrounding its roots. Focus on providing air and plenty of water, which they do need.

[Shadeflower]

Originally Posted by Ray

Yes and no. A more frequent, but more dilute feeding regimen mimics nature better, so is bound to be better for the plant.

That is exactly what I said...

Originally Posted by Ray

I disagree. For the most part, inorganic media like LECA, pumice, perlite, rock wool, etc., tend to store more liquid than does bark, and it is only when the mineral ions are in solution that it is available for the plants to take up.

I disagree. Inorganic has got the ability to take on more water, correct, however that is not what I was talking about, I was talking about ability to store nutrients. If you feed a high strength fertilizer through inorganic media it will all flush out straight away and a couple waterings later will still be inert inorganic media.
But do the same with bark and the bark absorbs nutrients, absorbing excess so that when you flush the pots some is flushed out but not all of it. To flush a pot filled with bark takes more flushes to fully flush nutrients out of a pot than in inorganic media thus proving my point 100%. Thank you for clarifying this.

Originally Posted by Ray

First of all, water is the driving force for growth, so being able to water more is a benefit. Secondly, adjusting the pH of the applied solution is of far less value than people seem to think. The plant itself, the microbes living in the pot and plant, and media have far greater control over the rhizosphere pH than does the applied solution.

I will opt to agree to disagree. Since you agree with me that fertilising regularly is better than once a month I was pointing out in order to achieve that one has to mix more fertilized water than just filling a bucket of rainwater and using it to water without making any changes, since you say that ph is not important to you surely using plain rainwater is then easier than having to measure out the right feed for every bucket.

I don't see why a perfectly good answer was analysed like it was when it still seems like a perfectly valid response to me so I have disagreed with your disagreements.

[Jmbaum]

I am enjoying how lively the discussion is and that everyone really leaning into both the in situ conditions and cultivation. I am seeing a gap here though. We have to establish the conditions of the system we are inspecting. Compare Apple to apples, so to speak. What is available to the plant in solution has direct relationship with the pH of the water. Inorganics (let’s just use this term for more innate mediums that are resistant to biological decomposition over the life of the plant) display a broad range of porosity, liquid retention, capillary action ect. and when we speak to in situ conditions and their emulations there is an arguably more massive set of variables at place.
So largely if we want to deal in absolutes, we need to be specific else it’s all over the place and unhelpful.

I for one would think what we can collectively establish for the benefit of future readers is some general principles

a) what can one expect from inorganic media and range there of
b) how does our care behavior change comparatively with one media vs another
c) what different types are available and in practice
d) advantages with respect to species, region where plant is endemic, locality of where cultivation is taking place.

Also, this absolutely brilliant discussion surrounding approximation of in situ conditions, traditional bark in pot, SH, gel media (ect) and the full range in between deserves a full flush out in it’s own thread. Would be amazing to have a full account of cultivation approaches in a single space, all variables, skill sets, access taken into account.

[Ray]

Originally Posted by Shadeflower

Inorganic has got the ability to take on more water, correct, however that is not what I was talking about, I was talking about ability to store nutrients. If you feed a high strength fertilizer through inorganic media it will all flush out straight away and a couple waterings later will still be inert inorganic media.
But do the same with bark and the bark absorbs nutrients, absorbing excess so that when you flush the pots some is flushed out but not all of it. To flush a pot filled with bark takes more flushes to fully flush nutrients out of a pot than in inorganic media thus proving my point 100%. Thank you for clarifying this.

There are several, apparently dissimilar, opinions going on here.

I feed a very dilute fertilizer solution at almost every watering. As long as the medium stays moist, it contains nutrients. I did not think about plain-water flushing in-between feedings, as with my regimen, it is no particular need.

I use a combination of LECA and rock wool cubes. The rock wool does flush pretty well, but LECA, with its communicating porosity, holds onto absorbed solutions quite well. Maybe not as well as some bark products, but in my mind, that’s good.

Where I think I disagree most stringently is in your assessment that the bark gives up a significant amount of the absorbed (precipitated?) minerals when it is flushed. If allowed to dry between waterings, the minerals precipitate wherever the solution had been absorbed. In order for them to redissolve, there has to be significant penetration of the water into the structure of the particle, time for it to redissolve, then time for it to diffuse outward. That simply isn’t that rapid with most of the bark products I’ve ever used, leading to greater and greater mineral buildup, which can ultimately become toxic, especially as the bark breaks down, releasing it at much greater rates.

I will opt to agree to disagree. Since you agree with me that fertilising regularly is better than once a month I was pointing out in order to achieve that one has to mix more fertilized water than just filling a bucket of rainwater and using it to water without making any changes, since you say that ph is not important to you surely using plain rainwater is then easier than having to measure out the right feed for every bucket.

I’m not really sure what you were trying to communicate with this paragraph, but I suppose that might be because dunking is not in my mindset about watering orchids. Overhead watering, preferably with a water breaker to simulate rain, is 1) closer to what plants see in nature, 2) oxygenates the medium by drawing air through it, and 3) actually flushes the medium, rather than simply diluting the contaminants, leaving the plant sitting in its own wastes. Please understand that I am not saying that dunking is bad (unless you do several in the same tub), just less preferred.

My “yes and no” comment was also meant to convey that feeding a strong dose of fertilizer is good for a month is not the preferred method.

I don't see why a perfectly good answer was analysed like it was when it still seems like a perfectly valid response to me so I have disagreed with your disagreements.

Herein lies the rub...

Your “perfectly good answer”, in my assessment, lacked enough background to help folks understand the “why” behind them, and that should not be disregarded.

We - OK, some of us - come to these online forums to learn how to make logical decisions when adjusting our cultural parameters to accommodate specific plants and our unique cultural conditions. Statements of “this works and that doesn’t” or “this is better than that” often fail to communicate the “for me, in my conditions” part.

My statements were mean to add the “why” part, and the disagreements came from scientific fact to some extent, and as I acknowledged up front, due to me not considering your particular (not clearly explained) methodologies.

[Jmbaum]

Thanks Ray for all the details, you’re always very generous with information.

What has been my general take away from everyone is that:
1. there is a range of inorganic media that have an array of water retentions, densities, availability and utility.
2. Most will not significantly effect the pH
3. The ability to water epiphytic orchids more frequently is the general goal. So media that allows the roots enough to “dry” after saturation has been met will improve culture.
4. Saturation time varies across different genus and subgenus
5. A lower (1/2-1/4) concentration of fertilizer applied more frequently is preferable to larger doses intermittently. This touches on what more closely happens in nature with the slow decay or organic matter by symbiotic organisms to make a stream of nutrients available to the plant.
6. Adjust accordingly