holy MOLY! You are fertilizer happy! :o) You DO realize that phosphorus does not wash out of the soil like nitrogen does. I wouldn't fertilize for blooming more than once a month.
If you are afraid of overwatering, make sure it has drainage. It isn't a cactus, but it likes to dry out some before watering... root rot would be a danger.
Good luck and happy growing!

They don't like a lot of fertilizer and they don't like a lot of water. I keep mine on a hot sunny deck and rarely water except for the rain it gets anyway. Keep REALLY dry indoors in the winter.

Hi

had a large one torn down by Wilma last year along with the shadehouse so decided to get rid of it because of the thorns. Have been spraying once a week or more with roundup
and it's still sprouting !!lol
That's one tough plant !!
gary

Hello from St. John,
Your getting good advice I fertilize lightly once a year and only water during a real drought.My bougs flower constantly and only turn green when they get too much rain. I know it hurts to prune but your plant looks leggy.I have learned that bougs can be pruned to whatever style you want the shape to be. I have many I keep about 6' x 6' in the garden and the same variety in a deck pots about 2' x 2'. They will actually bloom as bonsai. If you take it inside in the winter and keep it in a sunny window you will have it for next summer.The cuttings easily start in sand or perlite or soil.
Good Luck

FYI, it is 'Barbara Karst' not Karsten.

I had bougainvillea plant that I moved around my front yard a couple of time by transplanting. I finally took it and planted it at the base of a non flowering tree that stood about 25 feet tall. As the bougainvillea grew I got up on a ladder and trained it to grow up the tree. After about a year it really filled out and grew out between the tree limbs. It gave plenty of flowers using the tree as a support. I often had people ask "what kind of tree is that?" I let nature take its course, I never watered or fertilized it. It seem to bloom almost all the time.
Art

Do you think that a bougie could be planted next to an oak tree to let it climb? What about light? If under a tree is there enough light for it to bloom? My oak is about 25', but you know how wide they get.

I have one at the base of a Deciduous Oak, partial shade, it grows but never blooms. A former house had 3 planted against the North Wall - they grew like gangbusters but never bloomed. SO I'd not plant one in shade unless you like the foliage ;)