Well, you know, rosemary can grow into quite a large plant, and it will always want to get to its potential size.

Perhaps this would be a suitable question to ask on the Bonsai forum. Those people know a lot more about chopping roots and such. For myself, I'm very nervous about interfering too much with any roots, so I'd opt for the larger pot. Make your decision very soon, however. Your plant is (so to speak) a fish out of water right now.

When re-potting, either in the same pot or a larger one, give the plant an all-over haircut (not a drastic one!) to reduce transplant shock.

I would be more inclined to leave the roots and pot it in alone. I would just trim off the extra left behind. I would give it the sunnier position. I have carried over rosemary in too small of containers several different times over the years. With the top and bottom not going through much growth over the next several months I can't help but think you risk more damage to root prune and I wouldn't repot unless I root pruned. If or when you do this do cut back the top portion of the plant by a third or so to help balance out the root to top ratio some. If I did anything now it would be to cut back the top some to help balance the lost roots already.
Best of luck and Happy Growing David

I'm not quite sure I understand what hitexplanter is saying but I think I may be saying the opposite. It is going to be under enough stress indoors without being repotted so I would not increase that by repotting it now. I would just cut off the roots which are poking through the bottom and repot it in the spring before it goes back outside agaian. Otherwise I would leave it well alone until it is growing actively again next season. If you can be bothered I would try to put it outside whenever the weather allows through the winter.

Flora: We are saying the same as to don't repot now. Trim exposed roots. Maybe trim some of the rosemary back for the roots lost when you dug it up. I would give it the sunniest position inside that you can.

I have had several Rosemary's in undersized containers for several years. As long as they don't stay overly wet or overly dry they survive fairly well.

Rhizo has a good point about them attracting spider mites inside if you have them so be mindful of this.

Well, folks, you've all convinced me to leave the rosemary in its current pot, and trim off the roots that are poking out the bottom.

I'm happy that I was able to leave it outdoors into December this year, because that's another month or two that I wasn't trying to keep it going indoors. If I'm lucky, it will be back outside again in March.

Flora, you said:

If you can be bothered I would try to put it outside whenever the weather allows through the winter.

I thought about that. However, I'm concerned about the temperature shock of going from heated indoor temps to Winter outdoor temps. For example, I know a rosemary can easily handle 30F, but I'm not sure how it would do if it was suddenly exposed to that after being indoors at 70F. How warm would it need to be outdoors to make it reasonable for me to send the plant outside for the day?

The sun-burn can be another challenge to going outside after being inside for awhile. I would keep in a semi-shady location during these periods. If you have several days of 50's or above for highs and lows in the 40's I should think you are OK. I do take some of my hibiscus out if I get a warm spell in Jan. or Feb.and they do fine. I don't keep my house at 70 degrees however. Too expensive. 65 during the day and 55 at night. I use a space heater to heat smaller areas as needed. Good Luck and Happy Growing David

leira - do you have somewhere indoors which is not as hot as 70? I believe your rosemary would be much happier in as cool a situation as you can find, short of getting frozen eg unheated porch or garden room etc. At 70 it will be trying desperately to grow as if it were summer and it will not have enough light to do so resulting in sappy, etiolated shoots which are easy prey for bugs. Rosemary wants to doze through the winter - that's what it would be doing in its natural habitat. If you keep it as cool as possible indoors, going outside should not bother it and the air movement and light will help it stay healthy. It is not a tropical plant, so 70 is way too hot for it in winter. In my climate it stays out all year round. We are having a cold snap at the moment and I have no worries about my rosemary in temps hovering around freezing for a few days.

Hi Flora,

If it's not outdoors, I just don't have any other options beyond "the temp we keep the house," which is 70F when we're up & about, 60F when we're away at work, and 65F while we're sleeping.

On the plus side, this plant did survive indoors last year, and it wasn't nearly as healthy when it started, nor was it in the sunniest window available. Because of this, I'm hopeful. It was somewhat pale and spindly-looking by the end of it, mind you, but by golly, it was alive, and several months of outdoor sunshine did wonders for its health. It's positively thriving now.

One of the upstairs rooms might be somewhat cooler, at least some of the time, but there's also the danger of "out of sight, out of mind" and it could get ignored, never get watered, and die that way. I think one of the things that kept it alive last Winter was that it was in the kitchen, poor light and all, but that meant we saw it every day, and if it looked horribly dry, it got watered.

This is a difficult problem, to be certain, but last year's success (my first ever) keeps me optimistic.