Hi Mollie

First, you may or may not be doing anything wrong. It is hard to tell, but
what you describe sounds OK, except half a gallon of dilute fertilizer
sounds a bit much for only one plant.

What you have called a trunk and branch is an inflorescence. The fact that
it is turning brown is not an indication of a problem. Rather, the plant is
telling you that it is done with it. Listen to your plant and cut it off
about an inch or so from it's bottom.

How do the leaves look? Are they a nice bright green, or have they wrinkled
and discoloured?

When you water, does the excess start flowing out the bottom of the pot
immediately or do you have to wait half a minute or more from the time you
begin to apply the water? I learned this trick from an old grower yesterday
(old is relative: I am "mature" and he is probably only about ten years
older than I - but he started growing orchids many many years ago). He says
that if the water moves that slowly through your medium, then it has almost
certainly decayed to produce a kind of sludge at the bottom of the pot and
any roots in that sludge will certainly die.

Since this is your first, and I'm guessing you haven't repotted, and it no
longer has any flowers, I would recommend that you repot the plant and take
a close look at the roots. If the roots that had been covered by the medium
are solid and a creamy white colour, they are fine. If they are soft and
the colour of decaying turnip, then they are sick and probably ought to be
trimmed (if there are none that are really healthy, I'd leave them alone
since sickly roots are bound to be better than none). You want to visit
your nearest horticulturalist to get some bark, or coconut husk chips (CHC:
I would use medium CHC); and you'll probably find it easier to find the
latter (I have never found a local supplier of any kind of bark). If you
use CHC, you'll want to wash it several times (i.e. soak over night in fresh
water, drain, and repeat two or three times). If your humidity tends to be
low, especially in the winter, you will probably want to mix som moss in
with the CHC (sphagnum moss or spanish moss, depending on what you can
find). Sphagnum has antifungal properties, and so can be useful in
preventing infection should you find it necessary to trim the roots.

You say it is in a ceramic pot. Is that pot well drained? If not, you may
be killing your plant. Phals, indeed most orchids, don't want to be sitting
in water (in fact, IIRC, only marsh plants will tolerate saturated soil as
they all want air for their roots, but marsh plants are well adapted to
saturated soil and have other mechanisms to get oxygen to the roots). It is
one thing to display the plant in a ceramic pot, but I would grow the plant
in a clay or plastic pot just large enough to set into the ceramic pot when
I want it on display, and then easily remove when no longer on display.
Clay is preferred if you water alot because it breathes, while plastic is
good if your environment is dry or you don't water alot. Ceramic pots tend
not to breath because of the glaze and paint (and could be used instead of
plastic IF they are well drained - but good drainage is essential). If your
environment is humid and you tend to water alot, then you can get "orchid
pots", which are just clay pots with lots of holes or grooves cut into the
side of the pot. But these tend to breath alot and dry very quickly, so you
can end up killing your plant if you forget to water occassionally.

You DO know enough to feel the potting medium about an inch below the
surface to see if it needs watering, don't you?

Good luck.

HTH

Ted