What type of grass can grow under live oak trees? i have tried st. aug

Close to the tree roots I would mulch.

Other than that, it partly depends on where you live and your soil.

Costs nothing to talk to someone at a real local garden center

I don't know where you live, but here in Florida (North) I love the centipede grass. It stays low and covers very well. I started a Flower garden under my oak, but the only thing that likes it is Lantana and the Centipede. Very tolerant, better than St.Augustine.

It is probably too shaded so try sprinkling some shade grass seed under the tree and put a little fresh soil over top. Water well to get it going.

Artificial! it's not the 'tree' it's the shade -- even St. Aug that is shade tolerant, as is Blue Grass and some other varieties need at least 3-4 hours direct sun in the mornings. A ground cover -- like Ajuga would be fine -- don't have to mow it either!

try winter rye!