I agree with you about the lemon balm. Such a comforting citrusy tea. The plant, on the other hand, is every bit as invasive as any other mint family--and an incredibly prolific reseeder. I knew it was a spreader so grew it in a container. But, last year, when it bloomed, I forgot to cut the flowers off. This year I have it over half the back yard, coming up in the cracks in the patio, etc. So a word to the wise--grow it, definitely, but cut the flower off before they go to seed.