QuestionsHow to growLawnsMowingnewly laid grass seed 0 Vote Up Vote Down colette corcoran asked 16 years ago New grass seed put down three weeks ago. It’s coming up great but in some places it seems to be dying off in patches. Is there anything you can recommend for this or should we dig it up again. 1 Answers 0 Vote Up Vote Down Gerry Daly Staff answered 7 years ago Start mowing when the grass is 8 to 10 cm high and if there are remaingin bare spots, scatter some seed in showery weather. Do not dig up.