I came on this forum to ask almost the same question. I have a rosemary that I bought in a 5 gallon container last spring. I transferred it when I got it home into a bigger container(pretty plastic). When it started getting cold out, I moved it into my jacuzzi bathtub(lucky plant!) It is starting to grow, and it looks pretty spindly, and the new growth is pale green. I have it in the warmest, sunniest window in the house. Could it be too big for the pot? Does it need some fertilizer? Am I watering it too much, not enough? I would like to also train it to be more of a standard.... does anyone know how to do this? I will probably post this question on your forum since it does not have much to do with repotting. Thanks!

Most Christmas trees have a conical shape and there is usually a leader at the top. I don't know if Rosemary has single top leader, but with repeated trimming, I suppose it could evenually form into something similar. If grown in a mesh, it may poke stems through enough so that they grow out and then you cannot remove the mesh without damage.

Here, where rosemary is a an evergreen shrub, it's very dry during the winter. Most people who kill an indoor rosemary agree it's usually from overwatering. Since you'll want to let it get very dry between waterings, I would recommend pot weight as your gauge, not just feeling the top of the soil. When the pot feels much lighter, then it's really dry. Water at the sink so it runs out the drain holes, then don't water again until the pot "loses weight." Unless you have a giant pot you can't lift, feeling the weight of a pot is the best way I know to NOT overwater any plants wintering inside. Sand is not good stuff for container plants even if the ground where rosemary does well as a perennial usually contains a lot of it. You don't want a lot of fine particles of any type in a container soil. The fine particles fill up all of the spaces, eliminating necessary air pockets. Also, clay + sand = concrete. So be careful to NOT create that mixture.

You were correct in bringing your rosemary inside if you wanted to keep it. However, rosemary is a pretty picky potted plant, that has very specific needs, mostly related to drainage in the soil. You'll want to be very careful not to overwater over the winter--check the soil with a finger or get a water meter. With the cool temps, it won't be growing as much, and therefore not need as much water. Do some forum searching on rosemary and you'll see lots about keeping it in pots. You're also on the chilly side for lavender. Some of the newer hardy varieties can go to zone 5, but you're probably a bit too cold. It has very similar requirements to the rosemary--watch your watering and soil drainage.