yard update

My yard has been covered in thick plastic for about a month.  A lot of the weeds underneath are very brown.  But some were green! 
To kill the green ones,
I mixed up a non toxic "Round UP' alternative and sprayed it last weekend.
I boiled down a gallon of regular vinegar that is 5% acidic.  Boiled down to 16 oz or 1/4 the amount, so I think that should have quadrupled the acidity to make 20% acidity.  That's considered "herbicidal strength".  I added a dash of liquid dish soap and a T of rubbing alcohol.  Used my pressure sprayer. Will let you know!  I hope this kills the weeds, root and all.  Regular vinegar kills the tops of weeds, but if big weeds, they come back...