Rosemary's roots are easily waterlogged and require sandy/gravelly limey, well drained soil, especially in a container. But drought tolerance of rosemary is misleading -- you let a container-grown rosemary dry out and you're done. It won't recover. Rosemary is drought tolerant
in the ground only because it grows extremely long roots in search of water. This also means it can get pot bound very easily in a container.
In my experience, rosemary is tricky to overwinter indoors. I managed to overwinter for the first time last winter (tried 3 times and killed them dead). It needed 1C of water every day in a cool SW facing window sill, purposefully left sitting BETWEEN the window glass and the curtain at night to stay in the trapped pocket of cold air. In the spring when I repotted (I used crushed oystershells as the "gravelly" element), I discovered that there were 4 plants in a 6" pot styled as a Christmas tree though and extremely pot bound, so keep that in mind too. Not so pot-bound plant in a roomy pot may not need as much as 1C per day. The plastic pot was heavy after watering; light enough for the whole thing to topple over 24 hours later. Each morning, I gave 1/2C from the saucer, then poured the other 1/2C through the foliage in addition to misting all over with filtered water. I've read that rosemary is a coastal shrub (Rose-
marinus) and, contrary to popular belief, wants moisture on its leaves (I reasoned that morning "dew" was closest to nature). This container rosemary plants don't have a cultivar name (labeled as Rosemarinus officinalis) , but since they're from a nursery in southern California, I'm assuming they're not hardy in my area. I divided them into two pots with two plants each, and acclimated them outside as soon as temps rose above freezing -- I think 35ºF+ but I'll have to check my notes -- and they spent the season outdoors. I've been keeping them under a heavier spun-bonded garden cover (less light) for the past two weeks, and I'll be bringing them back indoors today since forecast for this week is low in the upper 30's. Two containers now, so I'll have double the chance to keep them alive this winter.
The hardiest rosemary variety is still a bit iffy in zone 6. This is my 2nd year trying to grow R. 'Arp' in the garden. Last year, I bought a plant in August and planted it, but it didn't survive the winter. Thinking that it didn't have time enough to establish a good root system, this year, I bought a couple of plants in early spring (ended up with a bargain as they were badly root-bound leftovers from the previous season that the local herb lady didn't think would sell among the fresh new rosemary plants) and planted them in the ground right away, in somewhat more sheltered locations than the last one. They have grown very well through the season. We'll see how they fair this winter. I'm planning to mulch them well.
Good luck with yours!
My most recent one looked fine for about two weeks and then it proceeded to crisp up to a pile of droopy, dried leaves.
. Keeping my fingers crossed, because they are slow growing and starting over from seed every year doesn't get you a lot of rosemary!
So let's all gloat about our upper 80's and low 90's weather and the luscious tomatoes, juicy peppers, and cool cucumbers that are just entering peak production right now to gumbo while we can ! 
