Need to eradicate large grass from garden it has large knobby nodes traveling a foot or so beneath the surface. What can I do? It grows over six ft tall thick roots, I dug out a section 8x10 last year, dug out all the roots, but this year it is popping up all over my garden.
It sounds like you have a grass that grows by rhizomes. If you have not planted your garden yet, use Roundup. It will be taken down to the root system and kill it.