Question
I reside in SE PA. I bought a beautiful hanging plant for my porch with southern exposure because bidens solaire requires full sun. Unfortunately,
when the sun is "high in the sky" the plant is not directly in the sunlight most of the day.
Flower production seems to have dwindled. Is that why or does the plant go through cycles?
In the meantime I'm trying to solve the problem
by taking it down and to expose it to full sun a few
hours a day. Did I buy the wrong plant? Should I
have a plant needing part shade or shade?
Thank you for your help.

Answer
I think you've solved the problem - Bidens needs at least 5 hours of dead-on sun including the noon hour when the sun is strongest.  It also does best when given a liquid feed every two weeks, but fertilizer alone won't make it bloom if the sun isn't right.  Do you have a sunny place where you could plant this in the ground?  You don't have to leave it in a hanging basket - you could plant in in a sunny garden, and get another hanger for your porch.

Impatiens, coleus, and begonias would all do well on your porch, as would any of the ferns commonly sold for indoor hanging plants.  

If a plant is getting four hours of sun in the early morning and/or late in the day, that is really a part shade situation, not a part sun.  The same four hours in the heat of the day is part sun.

all the best,
C.L. Fornari