very few flowers on my bougainvillea

I have three bougainvilleas (fushia, purple and orange). I've had them for about 1 1/2 years and they get some flowers but usually just one or two branches are touched with a few blooms at the end. I drive around and I see others loaded with flowers, what am I doing wrong. I was told they thrive on neglect so I don't water or fertilize. I planted them in sandy well draining soil. They look very healthy except for the lack of color. I hope someone can tell me what I'm doing wrong.

Thanks
Bassetts

yeah i'm not having much luck with mine either. i had it in a 10" hanging pot with lots of blooms when i first got it from the nursery. the green is growing, but all the blooms are gone. i suspect it may need more sun. thought it's on a south balcony, it doesn't get full exposure till noonish. i did repot it today in a 14" hanging pot and put a some mulch around it, so we'll see if that had anything to do with it. crossing fingers for me and you :)

I've heard you have to stress them out.....

How do you stress them out?

i've read that stressing them out includes not fertilizing for long periods of time and only watering when the soil is bone dry. but this is only my first bougie and i've only had it for a couple of months, so i'm no expert