Mg and/or Fe deficiencies

[Leafmite]

I agree Cym Lady. I just switched to an MSU fertilizer. But, the other alternative, which I practiced spring through summer, was adding suppliments. I added Ironite, powdered milk, and Epsom Salts. I still plan to add the suppliments in the spring, and summer waterings, though, as I liked the results far too well. And, I have added extra calcium to the calcium hungry plants for the winter.

[Cym Ladye]

Leafmite,

I do not know if you have a chemistry background, but if you do not, I would be very careful about using supplements with the already balanced-for-orchids MSU fertilizer. Adding trace amounts of calcium with each watering should not do any damage, but large weekly amounts may do more harm than good.

Unless your water is seriously lacking in iron, which most is not, as an additive it is just not needed as the fertilizers carry it. ... and milk? I have grown orchids for over 50 years and the only thing I use milk on is a paper towel to clean off my leaves......

Go back to basics for the next 6 months with the MSU fertilizer alone, and see if your results are acceptable. If you want to start additions in 6 months, get a water and soil analysis before doing so.

In my opinion, most people get waaaaay too involved with recreating the wheel on additives to well researched fertilizer balances. They may have good results for a few months, and then if they have overdosed on the premise of "a little is good but more is better", the plants start showing strange symptoms.

CL

[Leafmite]

I have a degree in Chemical Engineering and have grown plants for thirty-seven years. I use lava rock, see, and can't use the tap water as we have a softner. Bark, sphagnum, CHC, all are slightly acidic and contain nutrients that feed a plant as they break down but the rock, unfortunately, breaks down far too slowly to help my orchids much and provides a different pH. I saw evidence that my plants were suffering with just the MSU formula (and, yes, I did buy the right formula). I just used what works for my other plants and had no further trouble. I also add eggshell. But you are right, someone inexperienced with plants or the suppliments might not understand how to balance them or how much should be added or realize that I have lava rock and use rain or distilled water. That does make a difference. Thanks for pointing that out, Cym Lady.

[Ray]

Originally Posted by Leafmite

Bark, sphagnum, CHC, all are slightly acidic and contain nutrients that feed a plant as they break down but the rock, unfortunately, breaks down far too slowly to help my orchids much and provides a different pH.

If you think the degradation of your potting media are doing anything significant toward providing nutrition to your plants, you're fooling yourself.

Mineral nutrition is a complex subject, and what aplies to more terrestrial plants may be totally incorrect for epiphytes.

Sometimes mineral deficiencies in one ion give symptoms that look like deficiencies in others.

In other cases, a shortfall in one nutrient ion can cause deficiencies in others, by preventing the uptake or use of another.

And, if that's not confounding enough, sometimes an excess of one can interfere with the uptake or use of another. Potassium, for example, is a necessary ion, but to much can interfere with calcium uptake.

[Leafmite]

Thanks for the suggestion, David. I will have to research it and whether it is a good choice for all the plants.
Ray, yes, it is complicated. PH? I actually use bark and the moss in my mixes for plants that need a low pH soil as it really helps to keep it low.
Thanks everyone! This has been a great discussion!