1). These plants are or could be weeds somewhere. They are just not that
hard as house plants and beginners should not be scared off by theses posts.
In the beginning finding the spot with the right light and learning not to
overwater will be the biggest problem. Fertilize one or twice a month and
water heavily with clear water the rest of the time. The water you drink
will be fine, if you let the water sit overnight before use, that is even
better. Get a couple of different brands of fertilizer and rotate their
use.

The difference between a "good" and a "bad" grower may be location. I
know of someone who grew wonderful plants using a Poland fertilizer.
He was using RO water. He moved to another location, and was still
using RO water and the same fertilizer. After a while, the plants
looked pretty ugly.

RO and DI systems remove more than 95% of calcium, but many studies
show that less than 50 % of boron as borate is removed. There is a
simple table to understand the problem here :

http://www.watertiger.net/RO/countertop.htm
and a few others references.

When he started to add boron to his fertilizer program, the problems
disappeared... In some other states, there may be a boron excess,
obviously an high load would not be removed by RO or DI.

It is safer for hobbyists to use a mix of tap and rain/RO/DI water
anyway.

2). Foliar analysis is not a "magic bullet", just a useful tool. Optimal
levels for various orchids are not published. If they are not done
regularly, trends will be missed. Testing identifies the symptoms of a
problem, not the problem. Finding the problem often requires the help of an
expert. Example from here; tests showed tissue very low on P. Started
using a fertilizer with a higher P ratio, problem got worst. After talking
to the lab people, used a fertilizer with no P for a couple of rotations and
the problem started clearing up. (Problem was the pH of the mix was
preventing the plants uptake of P and the fertilizer with the higher P ratio
just made the pH problem worst).

There may be another problem with high P fertilizers. inc is never
supplied in large enough quantities and is easily bound as insoluble
zinc phosphate. Many orchids have a Zn normal foliar content between
80 and 200 ppm, very high compared to other crops. Zn can induce
deficiency somptoms in older leaves, and a chlorosis of the new
growth.






Another thing about foliar analysis is that it only gives you a very small
window of what is going on unless you are will to spend big dollars and cut
a lot of leaves. When I send samples, I will make a couple of samples for a
greenhouse. A single sample is composed of 1 oz of plant tissue. I make a
sample from 6 -12 good looking plants and a sample from 6 -12 bad looking
plants. A sample result represent an average of the 6 -12 plants and the
highs and lows of the individual plants are lost. I have found the
individual plant readings are all over the scale although everything in the
greenhouse is getting the same treatment.

Orchid scales depends on the genus, but usually some elements are much
higher than many other crops. Leaf tip or base, age, all play a role
to understand those analysis. Zinc deficiency is easier to assess
using the lower part of the leaves, iron toxicity the tips of older
leaves.

3). I know 4 or 5 growers who have cooked plants with MSU/Jack's/15-5-15
CalMag after using them almost exclusively for a year or so. Jack's is now
recommending a buffer (requiring a second injector) when using theirs. Use
these fertilizers with care and rotate with other types of fertilizers.
Watch the pH of what is coming out of the pot. Helpful 1 suggests checking
what is coming out of the pot every month or so. With my water, potting
mix, and fertilizer selections I find I must test more often. (Tied to the
pH meter thread of a few weeks ago, I find a $50 pH meter works fine for
this purpose. I know the pH of my clear water and when the meter is off by
more than 20% I know it is time to calibrate.)


Regarding those 15-5-15 CalMag and similar fertilizers. There are
several patents numbers appended to the notice.

http://www.scottsprohort.com/_docume...xcel/H4045.pdf

The patents mention how they can keep calcium and phosphorus together.
Urea phosphate complex. When the fertilizer becomes wet, urea can be
broken down. The oily liquid found in the improperly stored bags is
plain phosphoric acid, with the according pH. Calcium disappears, zinc
disappears, and sometimes even iron disappears. If a solution is
cloudy, the fertilizer is unusable. Fertilizer solution analysis for
professionnal growers is required, to ensure the fertilizer is still
usable.

I have seen some growers who add 15-5-15 CalMag to their water tank,
correct the pH immediately, and use it. They corrected only a part of
the acidity, and were burning their plants nicely.
15-5-15 CalMag and all other fertilizers must be dissolved as a stock
solution, and only once they are fully dissolved, added to the water
tank, and pH-corrected.

4). In both of Helpful 1's posts calcium nitrate is mentioned. This is the
third time I have seen it mentioned this year. The lab suggested I might
want to consider using a calcium nitrate solution in the first watering of a
flush. The other time I saw it (bags and bags of it) was at the greenhouse
of someone who was on the other side of major 15-5-15 CalMag damage. It is
something I know nothing about. Does anyone know what's up?

Calcium nitrate will stabilize the pH and calcium content of your mix,
especially if you do not use lime. 15-5-15 CalMag sometimes leaves the
plants with a major nitrate deficiency, owing to a specially complex
process. Do not forget that those fertilizers have been designed as
"plug" fertilizers, to dwarf the plants and ensure maximum flowering
on a small plant. Deficiency of a peculiar nutrient can be related to
another nutrient. Iron deficiency can be due to a long-term phosphorus
deficiency, as an example.