Fertilizing via the automatic misting system? Good or bad idea?

[cnycharles]

Who says nutrients can be leached by the use of pure water? I have never seen evidence of that or anything documented. Any reference I have seen relates to leaching of nutrients from soil, resulting in deficiencies and/or root damage. As orchids have evolved getting little beyond rainwater, I don’t see that last thing being a factor.

The absorption of a nutrient ion into a plant is part of a chemical reaction that results in the dumping of an equally charged ion into the environment, and once brought into the plant, it is incorporated into other chemicals. How is pure water going to leach them?

Back to the foliar uptake thing, it isn’t a matter of there being none, it’s just that it’s inefficient.

We aren’t talking orchids with solid leaves, but cuttings misted heavily to initiate roots. Millions of plants, thin leaves, no roots to draw feed out of. It’s common practice and it works. If you mist heavily and you see degradation, and you add feed and it stops and the cutting improves (no roots) then you are in business and don’t need a scientific paper written. If air moving over a leaf can draw water vapor out of a leaf, certainly lots of pure water can pull from the same process

 

[Ray]

Read my more recent posts, Charles.

 

[Sky7Bear]

Lance, what you described is not the leaching of nutrients by the pure water, it is starvation because the plants had no source of nutrition other than their own tissues, and that eventually ran out.

In my book, replacing the medium is needed. That, or a very, very long soak in copious amounts of pure water.

Ray, what book? I can’t find a reference in Amazon, Worldcat or your webpage.

But the question remains for me as a semi hydro grower about when if ever I have to physically remove and replace leca due to excess salts. You seem to be saying here that they adhere permanently to the medium. Thanks.

 

[Ray]

“In my book” is just an expression related to opinions.

Like everything else in orchid growing, “one size” definitely does not “fit all”, so there is no pat answer to “when to recharge the potting medium”.

All potting media “build up” over time, both with minerals and biofilm. Organic material decompose over time, so force us to replace the media. Inorganic stuff doesn’t, but that doesn’t mean it never needs to be replaced. Probiotic use seems to have a positive influence on biofilm control - I assume by introducing competing species.

When I had a greenhouse, where I kept the humidity high, evaporation was a “non issue” and I had some plants that had been in the same media for a decade or more, simply adding fresh LECA to the outside as I potted up in bigger containers.

Since becoming an in-home grower again (over the winter), where dry air leads to greater evaporation, I see evidence of buildup sooner, so a 3-year cycle of repotting seems more reasonable.

 

[cnycharles]

Read my more recent posts, Charles.

yes, I see something that really isn’t relevant to the original poster’s question. My responding at length, like the back and forth presently shown, would add even more distraction from the desire of the op to learn if feeding by mist is good or not. A moderator should know better than trying to be right at the expense of the original post
I think the amount of fertilizer the op’er is asking likely wouldn’t be a problem for awhile, but in a low humidity environment you could eventually get some crusting ands/or algae, and if you use citric acid in a feed then the lines could get filled with glop. It might be better to keep a misting system clean, and periodically use a hand pump to apply foliar feed if desired