In article g14Xc.313618$%_6.155311@attbi_s01, "Alan Grossberg"
wrote:

It's not an attractive option -- especially for a 500 sq. ft. area -- but
you could probably kill it or put a good dent in it with a cover of black
plastic mulch for 3-6 months.

Could also lay down a layer of cardboard, put some black compost on top of
that, then four to six months later upturn the soil (the cardboard will be
rotted by then) & have some really good rich soil instead of a mess of
plastic to pull up & throw away.

In either case, SOME of the mint WILL survive around the edges, but it'll
be a more manageable amount to dig or pull.

-paghat the ratgirl

--
"Of what are you afraid, my child?" inquired the kindly teacher.
"Oh, sir! The flowers, they are wild," replied the timid creature.
-from Peter Newell's "Wild Flowers"
Visit the Garden of Paghat the Ratgirl: http://www.paghat.com