I have several milkweed plants in large planters. Will they survive outside in winter? Is there anything specific I should do to to ensure they live? And yes, the deer ate much of one of the plants !!! Thank you!
Native milkweeds are deciduous perennials and there are several types. Following seed dispersal they die back to the ground. They remain dormant over the winter and reemerge in the spring.
Asclepias tuberosa is late to emerge in the spring.
You may need some winter protection to protect the root systems. In containers the roots are above the ground and surrounded by colder air. Air temperatures get colder than soil temperatures. You may be able to place the container next to your house and cover with pine boughs or shredded leaves for winter protection. Or even better sink the container in the ground to protect the root zone from the cold temperatures.