I haven't yet, but I plan on it.

I was at a nursery where they had a huge bougainvillea growing in their greenhouse. It is brought indoors every winter. The plant was stunning, and you could tell by the thickness of the stems that it had been growing for a long time. I think it would be worth bringing it in during the winter.

I know this doesn't answer your question, but I wanted to give you the option of not tossing it out at the end of the growing season.

There is another way to handle these plants. You could bring it into the house in the fall and force it into a semi-dormancy. Stash it in the basement, if it's cool there...restrict watering....not enough to kill it but just enough to keep it from growing. It will drop leaves and probably look like 'H..L', but it works with many plants.

Dave
Franklin.

I live in SE Wisconsin, and had a gorgeous Bougainvillea for 4 years. I simply treated it as a houseplant in the winter. If you have a sunny window it won't thrive but will stay alive. Last winter I stored it in a heated basement, and let it go dormant, watering about once a month. It died, so I don't think this will work.