Yes, they can be planted in fall along with garlic. They can also be planted in spring. Nurseries here offer sets at both times. When you plant just determines when you can harvest - fall planting yields an early summer harvest; spring plantings are harvested in late summer/early fall.

Many plant at both times :-)

In my area fall planted shallots have a tendency to bolt in early summer. I've never had any spring planted shallots bolt.

Fall planted shallots do have more of a tendency to bolt but I have always noticed that the flower stalk gets pushed to the outside of the bulb and doesn't affect their size or their storage abilities, unlike with onions. When I have planted in the spring the shallots have always been smaller for me.

Rodney