Answer: Bougainvillea are tropical plants and extremely frost tender. Their lowest temperature range is about 30 degrees, so when it gets cold, they can drop leaves and suffer frost damage. However, they rebound in spring. If your night time temps are predicted to be much colder than that, you might want to cover the plant to protect it. Use burlap, an old sheet or blanket or buy frost cloth. Put the cover on at sunset and remove it the next day before temperatures heat up to 50 or more, so foliage doesn't "cook" beneath the temp. If possible, drape the cloth over a temporary framework of poles or PVC pipe. The less the fabric touches the foliage, the less frost damage there is. Finally, although frost damage looks unsightly (blackened leaves) allow it to remain on the plant. It protects interior leaves from further damage. Wait to prune until new growth starts in spring so you don't mistakenly cut off still-living tissue. Good luck!
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