Hi Liewb
Here in Phoenix they thrive on neglect. In the ground they need little water and no fertilizer. Just admire the flowers for awhile and see what happens. They are strong plants. Maybe someone closer to your area can give you local advice.
They are subject to frost damage, but come back strong. They can take heat(118F) and very strong sunshine.
Good luck and
Happy gardening!

Well, they prefer root bound in a small pot, full sun and very little water. In the ground, they bloom only in dry areas like Arizona or Arizona, they refuse to bloom in humid area (like Houston, Tx)especially in rainy seasons.

Kquat.

Kquat-
That is good information.
There is one next door to me about 10 years old. It has masses of blooms continually except when it gets hard frost damage.
My wild seeded banana is loving the extra humidity of our monsoon season right now. It lasts about 6 weeks here in Phoenix. (Mid July through August) Outside of the monsoon time, humidity of 5% is not unusual. In a good year I get 6" of rain.

they refuse to bloom in humid area (like Houston, Tx)especially in rainy seasons.

Kquat.

We've got plenty of bougainvillea blooming here now. And Hong Kong is plenty humid and we're in our rainy season.

I am in Southern California and we are remodeling our house.So we have had to shut off the sprinklers. The bouganivilea is surrounded by concrete refuse and the white one is blooming spectacularly. Its in full sun. We are close to the ocean so although it doesn't rain much, its not really hot either. The red one in front is blooming like crazy and its in the shade. Southern California has bouganvillea all over. It really takes over. Its practically a weed--doesn't seem to need much care.If the leaves are yellow you are probably overwatering it.

Bougainvilleas love being root bound..they bloom better.

Yellow leaves is usually an indicator of too much water...water only when the leaves look sad. They don't like alot of water and if you live in an area where it rains alot you really don't have to water them at all.

They also love Hibiscus food every 2 weeks or so during blooming season. They bloom on new growth so cut the old blooms off.

They are the only plant that you can plant them directly into the ground in their pot as the roots will find their way out of the pot over time.

This summer here it was VERY hot, very dry and humid in SW Texas and they were beautiful.