how do I get more flowers?

[cleo88]

I want more tomato flowers.
Of course, everyone probably does. But I don't think I have my fair share.
My plants are green and healthy, so one idea is excess Nitrogen.
What about other factors?
Do I need more Phosphorous?
Is the fact that I only get 5 hours of sunlight influencing (negatively) the number of flowers I am getting?
Are there other factors?
Attached is perhaps the most dramatic example in my garden: a great looking, 2 1/2 feet tall plant (Maltese) that has been in the ground for 4 weeks and maybe has one teeny truss that I can hardly see. Frustrating!