Good suggestions.
It's possible that your grass is hay sprouting. That can happen if you've used hay for mulch instead of straw.
But if it is grass, it's likely it has blown in, as grass seeds are very light - I watched a contractor clearing an adjoining apartment car park recently. The car park had become a bit overgrown, it was the end of summer, lots of seed heads and after he had used his motorised weed-eater, he then used a huge leaf-blower which sent a cloud of dust, grass and weed seeds over the fence and onto my new patch of no-dig layers with mulch on top. I was trying to wave and yell at him, but he had earmuffs and googles on. Did those old seeds love their new home... did they what! ~ Megan ~
Aug 10, 2009
How to stop grass growing in garden by: Noddy
Grass seeds can blow in from other places and are a pain in the grass to put it mildly. There are sprays but as far as I know not organic ones, so rather than hurt the environment and risk danger to yourself and others, it's best to stick to organic methods to control weeds.
If grass is just on odd spots, sprinkle with salt or spray with white vinegar, or even get one of those propane gas flame weedkillers. But watch out for your good plants! You can also hand weed, like the good old days or shallow hoe. If you've got a real problem it's best to cover with no dig materials again, starting with thick newspaper or sacks or similar and then maybe a mulch and compost.
