Most Tarps aren't custom fit to the application, otherwise they'd be called a boat/car/etc cover and cost you 8 times more. Since that tarp isn't likely to have grommets in the right place, here's how you can still secure it well.
Not a knew idea my friend. I was told about this in 2005 when I was taking a course at the local community college. It also works when the grommet tears out
Thanks very much for this innovative idea! I've been dealing with tarps of all shapes/sizes for years and eventually went to dog-ears but in high winds they pull out (stopped using grommets years ago - they're the worst). Never thought of the rock/ball idea though. Will be incorporating that today! I concur with the truckers loop. Great way to cinch down a rope tight!
I have it on good authority that if you have no suitable rocks, Ricola cough drops will work also. You'll want to replace them after a year or so if you go that route though :) they eventually dissolve