I just read an article in ARBOR AGE about this, and it seems there is no
really reliable perfect remedy. Always the roots find some way to sneak
past or up beyond any of the commercial barriers available. Maybe safest
to dig out a really deep trench right alongside the driveway, and make a
thick cement wall there, then on the soil side of this wall, put all the
barriers sold. Some work by a toxic substance--which I as an organic
grower cannot honestly tell you to use. Others have various beens of
deterring roots, but so far there is nothing perfect.
You could try cutting off the major roots going toward the driveway,
cutting them off right where they come off the trunk, if you can get that
far back. Then coax the tree to increase roots in the other direction,
away from the driveway. Two ways to do this:
let a tiny drip of water from a hose drip at some distance away (and of
course away from the driveway) and also give plenty of really good organic
I have been able to keep a number of large trees growing in my small yard,
and not affecting the driveway or sidewalk, by coaxing the roots to go
where the water is--their natural tendency. I let a tiny bit of water drip
from end of hose, IN THE CENTER OF THE YARD.
People don't understand that root will go seeking water, desperately if
the water is in only shallow sites. I make sure that enough water goes
down in the center of the yard, so roots will go there and find it and go
down there. They don't have to hunt around elsewhere. I think that is the
reason I don't have cement cracking, as others do.