Do you know it is a perennial and not an annual verbena? Do you know the species or variety name - just to confirm that it will survive the winter. 

If it is Verbena bonariensis it should be fine to plant now and as long as you plant it at the soil level (not too deep but not too shallow) and use some organic mulch or leaves to put over it, it should take and come up easily next spring.

Feel free to send a photo if you would like help identifying.

Emily