Lemon balm loses it's flavor when picked. Lemon verbena will have fragrance and flavor when it's an old dried dead thing! I am thinkin' in your climate the Lemon Verbena also may be a bit more challenging. You need to look for a live plant to transplant. You can order them from a place in Canada so I know it is possible to grow it in Vermont though!
Lemon balm is good to grow from seeds though I think. Although, the lemon balm I got from OT has been the only one to overwinter and act like it's supposed to. When I've planted from seed it's never made it through the winter.
Thanks for the information! I thought I remembered your saying you preferred lemon verbena. Hm...I'll have to check at the next farmer's market. This time of year, it's mostly plants...that's where I'm hoping to get tomato plants, and it's where I got the sage. Most people sell six or eight plants for about two dollars, which isn't bad. I might get some chives, too. I'm about to give up on growing those from seeds. I tried last year, too...no go.
I bought that lemon balm "from the store" as a plant...I didn't plant it from seed. The lemon balm and mint that I brought from home are really taking off now. I need to keep 'em cut back!