I'm trying to remember whether I bought it at the grocery store or at Home Depot or Lowe's. It grows very well at "my house", not very well at "The house", and it looks like it's out-competing the oregano here.
I planted it on the north side of my house here. I thought that was kinda risky but I had an empty bed there and really wanted that whole bed full of lemon balm. It's about 6 square feet. The lemon balm has covered most of it now.
I bought my lemon balm at Lowes last year. It did okay. This year it's HUGH. And it's growing in a partially shaded area.