"Johnny" wrote in message ...
A giant 30+ feet pine tree is growing wildly one foot outside my fence.
All the tree root are growing underneath inside my garden.

So you do not own the tree, right? It is outside your property, right?

The tree root and stubs are all over the surface of my garden.
All my grass and plants die.

What type of garden? A garden where you will want to till the soil to
a depth of several inches?

I want the root stop growing into my garden. Better yet, I wish
this tree stops growing.

So cut the roots off with an axe and then dig them out with a shovel.
A stump grinder might also be useful.

Dave, I am in Seattle. Dig a trench seems like to right thing to do.
That will certainly ruin my garden. I plan to covering the entire
area with rocks. How do I remove the roots?

So if you plan to cover the area with rocks why do you care about
roots? Why not simply cover them up with a deeper layer of rocks?