Question
I heard that Bougainvillea have a pretty hardy root system and can over time destroy a foundation.  Is this true?

Thanks for your time,
Bree

Answer
Yes, it is, but only if you let them get out of control. Here's a picture of the hillside in front of a house that I used to own:

http://www.abouthomes.info/pics/Bougainvillea%20hillside.jpg

There were seven out-of-control bougainvilleas. Each bougainvillea had a height of about 20 feet and a spread of about 20 feet. They literally were tree size, with a trunk and root system to match.

Here's a close-up of one of them from the driveway above:

http://www.abouthomes.info/pics/Bougainvillea.jpg

Ultimately I pruned them back severely so that they were just seven sticks in the ground about six feet tall. I let them grow back in a controlled manner so that I had a standard--a tree-like specimen--that I could walk under so that I could create some paths on the hillside and plant something in addition to the bougainvilleas.

The bougainvillea does have some severe thorns; roses don't have anything on the ol' bougainvillea. However, there are now some very nice dwarf bougainvilleas on the market that come in different colors and are thornless or practically so. Some of the interesting colors are those where the flower bracts change colors as the age. I have an orange one that starts out as gold, changes to bright orange, and fades to gold:

http://www.abouthomes.info/pics/Bougainvillea%20gold.jpg

There's also a "pink" one that starts out as white, changes to bright pink, and then fades back to white. Unfortunately, I don't have it yet.

One should not plant bougainvilleas near the foundation of your house since the roots can cause damage to the foundation, and the very abrasive branches and thorns can damage the siding.