sometimes you can let the grass grow to 6 - 8 inches tall for one season right... and shade them out.... always experiment, and Nature will show you the way... personally i don't like lawn that much...because you become a slave to it... i'd rather have it as a wide path here and there and then have something ornamental instead ...like IVY or vinca ..
talking about round-up ....man i was walking my new place and i'll be needing 3 or 4 gallons of that stuff soon to kill all of the poison ivy i have.
then i will need a huge area just to grow ground covers to plant in the spring to compete with the Poison IVY....until i finally kill it all. I'd rather have a 10 inch layer of ground up leaves instead covered up by cardboard that was soaking wet....anything that worms can eat.