If you have a purple Bougainvillea, you are probably referring to the color of the bracts. The flowers are white/cream. I had one that did the same thing as yours, so I put it in a deep pot & gave it full sun. It took awhile, but the bracts are starting to come back. I transplanted mine in the spring. I also added an extended-release fertilizer with transplantation. After it comes back & gets healthy you can consider returning it to a bonsai method of growth. You might consider giving it a well drained soil & gradual adjustment to heat. These plants do not like wet feet, & thrive in drought tolerant zones. BougainvilleaÂs tends to dwarf in pots compared to being in the ground, which would probably be good for bonsai. Watering depends on the zone. I have mine (not bonsai) in a black pot & water it daily. The heat dries out the soil within hours. It is not uncommon for this plant to die with transplantation.

Hi Everyone, Thanks so much for the advice. I'm looking at a few different light rigs for my bonsai. Home Depot is selling various T5 panel variations that I'm looking at. They are a bit pricy and some have questioned whether they are worth the price. So are Compact Fluorescent full spectrum bulbs a worthy substitute for the pricier counterparts? All of my bonsai sit in a southern facing window that gets a healthy dose of natural sunlight. My previously lifeless serissas are now exploding with growth and blooms. With winter coming, I want to be sure I'm caring for my plants properly -- especially those that need high light to maintain good health. If I can get away with spending $25 vs. $100-plus, then I'd rather do that. Also, I'm heeding the advice with the Bougainvillea and watering to see how drier soil affects the yellowing leaves. I'm not concerned with making it bloom just yet -- I want to make sure I can care for its basic health first. Once I start to see signs of good growth and reduced leaf drop, then I'll consider different methods to produce the blooms I would so love to see.

Nothing. There's no need to use anything and sometimes using something can keep in bacteria and not allow the cut to heal properly.

Lots and lots of work is needed here. Rather than my going on and on, follow the below link and peruse the entire site for a wealth of information. There is also a forum with a single post about Bougainvillea: http://www.bonsaiempire.com/forum/help-me/6957-bougainvillea-bonsai-trouble Here is a link that might be useful: Care guide for the Bougainvillea Bonsai tree