I have been able to positively identify dogbane, growing near Lake Monona, in Yahara Park, located here in Madison, Wisconsin. It has milky sap, and the leaves look a lot like milkweed leaves. However, the stems will have a reddish tint, that is not hard to see. Your plant has green stems, so I suspect it is milkweed, not dogbane. When it flowers you should be able to make a positive ID. I grow three types of milkweed in our yard, Asclepias tuberosa, A. incarnata, and A. syriaca.

I would not do it. You likely won't see monarchs until early June. If you want monarchs laying lots of eggs on your plants, you don't want old plants. I'd suggest having your milkweeds seeds sprouting around the 1st or 2nd week of May. The trick is to have young plants that are attractive to egg laying monarchs plus have enough leaves to feed the caterpillars. In my experience, monarchs' favorite milkweeds to lay eggs on are around 2" tall. So when I say they like young plants, I mean YOUNG. Once you get your milkweed established, make sure you check the tiny plants that are coming up later in the year. They will come up from the spreading rhizomes.

"they are now stirring, and preparing for their journey north from Mexico." She asked for help, so that the Monarch population heading north from Mexico, would have enough host plants along the way towards Canada. These days people in the south should cut their Asclepias curassavica, nivea, Gomphocarpus, and Calotropis down to the ground before the Monarchs start migrating south again, so that the Monarchs returning south won't get infected with OE, and they won't be tempted to leave the migration and lay eggs. I've grown Asclepias curassavica and Gomphocarpus physocarpus, so that there would be a lot of leaves for the caterpillars, and I'm simultaneously growing milkweeds native to my area which can take years to mature, and are still too small to feed caterpillars. I don't think Asclepias curassavica and Gomphocarpus physocarpus are listed as invasive in the USA. I think Gomphocarpus is invasive in Australia. I agree that people should focus a lot more on growing nectar plants for the adults, and the lack of flowering plants they can use, may be more crucial than growing the milkweeds at this point. Studies have shown there are enough milkweeds around for them, it's the loss of habitat and nectar plants along their fall migration route that's making their numbers decline. There is a population of Monarchs that stay in the deep south and don't go to Mexico. They have the highest infection of OE. No doubt because many people in the south grow the tropical milkweeds year round and never cut them down, and probably quite a few aren't even aware of OE. Everyone should plant more fall blooming plants for the Monarchs.

Joe, I wintersowed some milkweed seed this year. It's up but still small, I have most of those other plants that are mentioned in this post. Don't forget to plant some Maypop for the Gulf Frits. Yes, I get them here in NE OK. They have had a program going at the botanical garden in Tulsa in past years. Not sure if that's still going on. Also I grew fennel last year and I had a lot of those Monarch caterpillars on it. With fennel, IF they leave you anything, you can use it in cooking or just enjoy the fragrance. But usually they strip the plant down to bare stems. They can be found in dill umbels, too.