Good Housekeeping researchers found that ketchup, mustard and grass stains top the list of hard to clean stains.
"When you get a grass stain it's most likely ground into the fabric and it's a protein stain so what you want to look for and what you want to use is a laundry detergent that contains enzymes," said Carolyn Forte of Good Housekeeping.
Those enzymes are good because it gets deep down into the fibers.
"For condiment stains like ketchup and mustard the thing you don't want to do is rub them into the fabric. So while you're at the picnic or the barbeque, just take a plastic spoon and scrape off as much of the excess as you possibly can. Then just dip a paper towel or cloth if you have one into some cool water and damp the stain," said Forte.
As soon as you get home, put a little glycerin on any mustard stains. For ketchup stains, flush it from the back of the fabric with cold water. Then rub the stains with a soft toothbrush to remove any sugary residue. Finally wash using your hottest temperature setting and a bleach that's safe for your fabric.