About the only nutrient deficiency that is going to manifest in
orchids readily is iron; what you have doesn't sound like iron deficiency,
and you're already putting iron on 'em. The second, much less likely
deficiency that is seen in orchids is that of calcium, which (because it
affects growing points first) isn't your problem.

I don't think you have a nutrient deficiency. I think you have
salts build-up or, at least, that's the best I can guess without seeing
the plants. Any pictures available?

If you have problems with root tips dying back, this would lend
strongly towards this theory. More salt-sensitive plants (phrags in
particular) that are in the same medium would be better indicators.

Some people have reported bad problems with salts buildup using
coco fiber, even when thoroughly washed (and checked with a TDS meter
afterwards); it seems to accumulate salts, at least here in the SW where
our water is pretty nasty sometimes with regards to dissolved solids.

So- check your media, let us know if there are any mineral crusts.
How are your root tips- dead or alive? Are more salt-sensitive plants
showing any signs of stress? Do you ever use magnesium sulfate (Epsom
salts) to exchange out some of the built up calcium carbonate? How much of
the fish emulsion do you use? The 8% sodium is high, but expected given
that it's probably from a marine environment, which already has lots of
sodium present.

If all else fails and you don't want to believe me when I say I
don't think it's a nutrient deficiency, then switch to a fertilizer that
lists all your elements, right down the list:

Nitrogen, phosphorus, potassium

Iron, calcium, magnesium, manganese, zinc, boron

Cobalt, copper, molybdenum, and iodine.

Easy on the zinc. It's a little toxic if you use too much.

Still don't believe me? I'm cool like that. Get yourself a bag of
"Guaranteed* to Grow!" or something like that from the local hydroponics
store, some sort of micronutrient junk that is whipped up by some guy in
his garage. It's a cheap way of getting your micros in a convenient form.

By the way- do you know what a molybdenum deficiency looks like in
dendrobiums? Neither does anyone else. :-)

* Guarantee not good when used on plants, animals, or any other life form


No e-mail to the address in the header. It's a spam trap.


Cheers,

-AJHicks
Chandler, AZ