First I try to wash it..because sometimes it will come out anyway. And sometimes it looks like this:
yikes!
So here is what you do. If it's still damp from the washer, simply lay it on a flat surface in direct sunlight. If the clothes is dry, spray it with water until the stain is throughout wet.
And now all you have to do is wait until it's dry....and voila! the stain is gone.
No harsh chemicals and the best thing, it's FREE! I would just recommend to wash it again since the fabric is probably a little stiff from laying in the sun and maybe dirty again with pollen, etc..
Now you and your little ones can enjoy the cute baby outfits a little longer without getting frustrated about stains anymore.