If you're only growing as an annual, in my opinion you can't beat standard Tuscan Blue for flavor. Been happy with the BBQ too. If you want to try overwinter, you might succeed with hardy ARP, or Madeline Hill Hardy. Both say zone 6, but it depends so much on the microclimate. I did get an Arp overwintered here in 5b in a way--it didn't die, but didn't thrive or really produce much the next summer, so I quit trying. It was mostly an experiment.

Mostly, you just want to make sure your mix is well draining--what are you using in your raised bed?

The planter box I use is this one and it drains well. The bottom has slats that have small spaces between them and the slats are covered with a porous fabric. I usually fill the planter with MiracleGro planter's soil mixed with compost.

Are you talking actual garden soil, or a potting mix? I didn't find the product you listed, and personally don't use Mir Gro. I haven't done that type of raised bed, but believe a potting soil to be better draining than garden soil. But, if you've done it before then you probably already know how your blend acts on your situation. I do mostly pots, EarthBoxes, and inground.

Also, as a side note, many herbs should be perennial in zone 6, even raised if you can protect it a little. Oregano, thyme, sage, chives, tarragon, sorrel, etc.

I was referring to a potting mix. I use the Miracle Gro with moisture control and I've had good success with it. I fill the box with new soil every year.

I personally wouldn't try rosemary overwintering rosemary outside below zone 7. I've tried the hardiest ones here to no avail.

FataMorgana

Rosemary Arp is hardy to Zone 6b.

Technically, yes. But rosemary is so sensitive that the microclimate of the spot it's planted is major to it's survival. And the drainage too--cold means not draining, and if it's frozen under, with soggy top--hello rootrot. So, while the varietal will technically handle the temp, there's so much more that goes into actual survival.

I actually lost my chives, sage, sorrel and burnet this winter--all hardy for my zone and further, but succumbed still.