I planted a small fig in the small garden on the south side of our house; it's immediately next to the house. THis garden is only about 18" from front to back, the sidewalk is bordering it. This tree has grown enormously since being planted there in the spring; from about 2 feet to 6 feet. Is there any danger of the roots going down to the drain tiles of the house? It's about 3'5" from the soil surface to the basement floor, the drain tiles would be a bit farther down than that I think.