Another thing to consider is fertilizer - how much of what formula do you
use, and how often?

Switched fertilizers this spring to a balanced urea-free formula
16-17-17
N 7% ammoniacal
9% Nitrate Nitrogen
P (P2O) 17%
K K2o) 17%
Sulfur 1.9%
Boron .015%
Copper .015%
Manganese Ch .03%
Molybddenum .011
Zinc .015

4T dissolved in a 6 oz bottle with about 1/2 t superthrive and water.
This concentrate is easy to dispense and doesn't precipitate at room
temperature. I then use 1 T. per 2 gallons of filtered tap water (not
RO) fed once a week. The rest of the water (usually every other
watering) has been with collected rain water when it was available.
There was a long dry spell when I ran out of the rain water.

Most are potted into deeper pots (some 4" some 6") with CHC, coir,
perlite (roughly 2-2-1). The chips were soaked and rinsed at least 3X,
the coir soaked. The pots were probably too big, and they have been in
them for more than 6 months. They are in trays to catch the run off.
The trays are actually marketed as 'shoe or boot trays', have a grid
pattern in them so that the pots are 1/2" above the collected water.
There is some browing of the leaf tips. Maybe a little more water in
the tray? A thorough flushing with rain water? Too much rain water?

They are set on a covered porch on the northeast side of the house.
Trees block most of the morning sun, it is bright but dappled. The
most sun comes from 10 am to noon, it is unshaded. Some (very little)
is available late afternoon when the sun comes past the corner of the
house. The biggest plants nearest the hand rail received the most sun.
They didn't seem to be adversely effected by the heat or intensity, no
burning or wilting.

If you are in sensory overload, the phrag that bloomed was in S/H. It
has been in S/H for a little more than a year, maybe 2. It was a Phrag
Inca Embers. It had 3 divisions when it bloomed, now is starting a
4th. I don't remember now how long I've had it. More than 2 years
anyway. Come to think of it. It had gotten separated form the rest of
the phrags when I moved them in last winter. All the others were in
the northeast of the room, it was in the southeast.

Still open to suggestions. Many thanks,
Nancy