Light Questions - What Exactly do the recommendations mean?

[cjm3fl]

Duration is another consideration.
I grow outside but my Phal's begin setting blooms during the part of the year with the fewest hours of daylight (Jan and Feb).

Some commercial growers "trick" plants into bloom by adjusting the duration, as well as intensity, of the lighting.

Sorry. I know it's something else that just adds to the confusion.