My opinion: use them whenever you want, but in different concentrations,
based upon the amount of nitrogen you want to apply. As you didn't include
the actual makeup of those nutrients or the trace elements, I really didn't
have the options of "always" or "never."

Generally, I feel that there is a minimum concentration needed for most
elements, with the nitrogen being the critical factor - you don't want too
much or too little - but the rest are sufficiently available in most good
brands. Unless you're really overdoing it or not rinsing the excess
minerals away with the occasional fresh-water flush, it's doubtful that
you'll get too much of them.

And as is the case with vitamins for you and me, your body will take what it
needs and dump the rest, so watching them is less critical, as long as they
are available.

--

Ray Barkalow - First Rays Orchids - www.firstrays.com
Plants, Supplies, Books, Artwork, and Lots of Free Info!

.. . . . . . . . . . .
"Just Nice" wrote in message
...
How and when do I use these formulae:

N13 P27 K27

N21 P21 K21

N18 P36 K18

Regards.