I just grow the native milkweed that grows wild. They are not pretty but the Monarchs like them.

Ascelepius incarnata is garden worthy and doesn't sucker all over the place like the one Triott mentions.

I have found a nursery that sells the incarnata plants and will be buying some tomorrow. Does anyone have any experience in growing milkweed in zone 6b? Any advice? Thanks...

You can find details of native varieties for each zone here . http://monarchbutterflygarden.net/milkweed-plant-seed-resources/

The Audubon Society in Pittsburgh gave a talk about this at Phipps a week ago. You might check their website.

I'm happy to say my milkweed is really thriving. I put a temporary fence around it to keep the dog from trampling the baby plants. Some of them are now 4 feet tall, and they are already starting to bloom. I'm sure it's too much to expect to see caterpillars this year, but maybe next.

An interesting thing I learned at the talk was that native milkweeds are better because the tropical varieties nurseries have bloom for too long. The Milkweed starting to yellow and die back is a sign to the butterflies to stop laying eggs and to build and conserve energy for their flight back to Mexico (or California west of the Rockies). The longer bloom time of the tropicals makes them hang around too long and they die before making it to Mexico. Apparently it takes them 5 generations to get here from southern Mexico then one generation goes back.

That's fascinating - thanks for sharing that. My milkweed is the native variety, so I won't be confusing any butterflies.