Answer: You will need to bring it indoors for the winter every year. You can either keep it actively growing as a houseplant, or allow it to rest in a cool place. During fall and spring, you may want to set it outside during the day and bring it in at night to try to extend the growing season as long as possible.
Do not panic if it defoliates when moved inside, this is fairly normal. It is a cyclical bloomer so look for periods of vegetative growth alternating with blooming. If you need to prune, do so right after a blooming spell and/or in late winter.
To keep it growing as a houseplant it will need at least six hours of strong direct sun at a cool room temperature of about 60 to 65 degrees. Bring it inside before temperatures drop below the mid 50's. (If you wait too long it will begin to slow for winter naturally.) Water sparingly as overwatering can cause the roots to rot. Fertilize lightly while it is indoors. If you see it become leggy during the winter, you may want to add a grow light for it.
If you opt to keep it just resting, leave it outdoors a little longer until temperatures are in the mid forties so it stops growing, then store where the temperature is cool but above freezing, the temperature should be about 40 to 45 degrees. Trim it back when you bring it indoors. Water just enough to keep the soil from going bone dry. Do not fertilize during the winter.
In spring, as the weather moderates and temperatures stay in the 50's and above gradually acclimate it to being outside again. Resume watering and fertilizing as it begins to grow again. Good luck with your bougainvillea!
Q&A Library Searching Tips