Question: We planted a very small fig tree next to our wall 11 years ago, and now it is taking over the whole backyard. I heard the roots can do considerable damage to our plumbing and wall.
If the trunk is closer than about 3 feet, I might worry, but otherwise, I would not unless it is getting its water from your neighbor’s yard. If it is getting a lot of water from your neighbor, then this will pose a problem to your wall in the future.
Always water on the side of a plant away from a wall or foundation. It will not be a problem to water on one side of the plant while not watering on the other. Plant roots will grow where there is water and not grow or grow poorly where there is none or it is limited.
Whenever possible, try to keep soil within 3 feet of a wall or foundation as dry as possible. This helps to reduce problems with roots and corrosion of concrete by soil salts.
As a safety precaution, you can cut the tree roots on the side toward the wall. Leave the roots exposed to heal a few days and then you can bury them again. Figs in particular can handle severe pruning.
Bob Morris is a horticulture expert living in Las Vegas and professor emeritus for the University of Nevada. Visit his blog at xtremehorticulture.blogspot.com.