Is that the one that smells so good? I think it would help if it's obviously suffering, but if it looks ok I'd let it grow thick.

I think you mean Asclepias syriaca - that is common milkweed and the flowers do smell fabulous. I've never heard of growing it in a container, but that is great yours is doing well.

It spreads by rhizomes so you probably have more roots growing in your pot each year, and so you are getting more shoots. I don't know if it would make a stronger plant to thin the shoots, but maybe you would get fewer, but larger stalks if you thin them. On the other hand, if you fertilize adequately they might all get large and thick?

My patches get thicker each year, but they are growing in the ground and they start sending out errant stalks here and there.

Do you get Monarch butterflies on your milkweed?

When I went to Maine a couple of years ago, this smelled so good I had to pull over and check it out. I could smell it with the windows up. I think people want it in pots because it does tend to spread a lot.

Thanks for the responses. Yes it is Ascelpia syriaca... I have it in my urban garden, but it never gets enough sun to really show off. I'm hoping this is the year. After reading your posts I'm just going to let it go and see. We do get some caterpillars in the garden but, hey in New York City, it's a jungle out there.

What kind of fertilizer do you use? I thought they liked poor soil?

Well I usually see A syriaca growing in good soil in the wild. And I've got 3 small patches that planted themselves in this yard, and they are all in medium soil. They are drought tolerant once established although I'm not 100% sure of their nutrient requirement.

The potting soil or mix in containers will get depleted of nutrients quickly, so you generally need to fertilize. So I usually use a weak liquid fertilizer in containers (in the ground I use mostly compost, occasionally an organic granule type fert.).

Thanks for the info. They are in a pretty deep pot, well it's a 5 gallon bucket actually... The stems seem much thicker this year. Last year I had 4 stalks and it looks like there are about a dozen this year. I think I'll keep giving it the attention you all recommend and not cut any of the stalks as they seem thicker. It may be that they are in a sunnier spot than last year too.
Fingers crossed, waiting for Monarchs (we have gotten them to stop by before)
Happy Gardening everyone!