When you trim a vine section..it will branch out below your cut...most times.And they flower
better(all down vine)when are around 18-20 inches long& I've only trimmed mine when was done flowering.
I grow mine in hanging basket its moss lined.It gets more sun now,but around end of august it will start flowering and I'll move it up on porch then.I'll keep in my cold GH with bright light(sw)it will bloom till almost march.My cuz lives calif and his blooms about 11 months.He uses 20 inch clay pots.He has bark chips mixed in his mix.He's doing the time release fertilizer 12-6-something& a bloom booster one the rest of time.I can see mine looks alot better with getting fert all the time.i've used hibiscus fertilier in the past.they are not cold hardy.4 hours below freezeing is a dead boug plant
.I'm a TX 8b and we don't get below 15 much& rarely over 6 hours below freezeing.My cold GH is vented.we uncovered the eves cause sometimes we get too humid in there& this way air circulates when is a breeze.it hangs about 8 ft up& I don't cover it& would guess is 3-4 ft from light I leave on when it does go below freezeing.They do best root bound& you don't want to damage roots on bottom(like set pot on ground& have feeder roots grow intoground)I grow in moss lined basket so gets plenty of air& the air keeps my roots in check my hanging basket is a 10 inch,but would like a 12 inch.I know a bougainvillia will grow in a 1 gallon pot for 3 years.I've never seen a tree
form one grown,but have seen an espliear one grown& I thinks....catlover on here grows on out Calif in ground and hers is just invasive & wacks it and its still just plain happy.I kinda like mine to have long vines hanging over basket.
I read an article once on the Houston bougainvillia page about pinching for shapeing.I do rember was pinching every 4-5 weeks& seemed it bloomed more down the vines.I read they sometimes produce seeds
,but have not seen any on mine so guess I must have a hybrid.Its pink...its awesome& I like a orange one with variegated leaves.And hear is a yellow one and its leaves are more lime green.