Just curious, but why are you growing milkweed?

Butterflies - monarchs, maybe?

Al

Yes, milkweed for Monarchs.

Cool! We have lots of milkweed in the meadow behind the house & I usually send the grands a few chrysalises each year to enjoy when they emerge.

Ohhhh boy! What a story I have about us returning from a weekend away. My son had stashed the cocoon of a cecropia moth in his room. My wife's screams had me bounding up the stairs 3 at a time, to find her standing on his bed with her hands tight over her eyes & facing away from the newly emerged moth (wingspan wider than an English sparrow) that was hanging from the door header & slowly pumping fluid into its wings. I was soo surprised that she cared not a whit how intricately beautiful the delicate creature was. Women! ;o)

Al

Here is a link that might be useful: What she saw . . .

I'm sorry, Larry. I got so carried away with my story, I didn't notice your question was still unanswered - please forgive me.

If you're growing common milkweed from seed, they will like a spare soil you can keep on the dry side - they won't like wet feet. There is no reason they shouldn't perform well for you in containers.

Al

Al, thanks so much for your answer and the anecdote, "women" is right but we can't live without them. I have the plants in one gallon containers that I bought from a local nursery, I would like to know how big a container I will eventually need. I imagine any good commercial mixture will do since my understanding is they are not too particular about soil.

Larry

In case you were wondering, the expression "Women!" was offered in totally feigned incredulity. ;o)

I think that if I was going to use a comercially prepared soil, I would really make it spare by adding plenty of one or more of the following: perlite, Espoma Soil Perfector, Turface, Haydite, crushed granite, fine gravel or 1/2 BB size silica - you get the picture. If it's common milkweed (still not clear which species you have) you really cannot afford a saturated layer of soil at the container bottom w/o impacting vitality.

The plant reproduces very easily from buds on spreading roots, and it can fill a container in no time, so 'sky's the limit' on container size (though your soil will certainly impact what is prudent unless you do decide to use a very free-draining soil.

Al