I hope it isn't rude of me to resurrect a thread from a few years ago, but I came across this thread while searching for information on controlling asclepias syriaca, more specifically, whether the rhizomes can be contained so as to prevent them from taking over (the seeds I'm not as concerned about). I have a couple of 1 year old syriacas in my garden (planted last year), as well as some new syriaca and purpurascens seedlings I have started indoors. I'm just now realizing/reading about how aggressive established syriaca can be. I have been fighting ongoing battles with Japanese knotweed and bindweed in my garden, which makes me very leery of inviting more rhizome-related trouble! I also have a fairly small garden, which means that if the syriaca begins spreading, it will quickly be popping up in my raised veggie beds on the one side, or in my rose/perennial beds on the other side. That said, is there a way to contain the syriaca rhizomes? Jazzygardener, above, mentions black plastic landscape edging--do others recommend this approach? Perhaps I'm overly cautious because of my J. knotweed experiences--those roots spread far too deeply underground for some black plastic to do much good, but J. knotweed is somewhat notorious for that so it may not apply to syriaca. If black plastic would work, what about large nursery pots sunk into the ground? Or alternatively, might it be a better idea for me to focus on better-behaved asclepias that would be more manageable? As mentioned, I do have some purpurascens seedlings and from my reading, it looks like there are many other asclepias varieties that are better behaved. I don't want to do the butterflies any disservice, but I don't know if I can take on another garden battle! What would you recommend? Thanks all for any thoughts and opinions. :)

"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.

If you can get or grow native Texas milkweeds, good for you! Always good to use the plants native to your area. But if not, don't worry, Tropical Milkweed is native to Mexico, which is our neighbor, not far away. There's been a lot of BS printed about Tropical Milkweed, which is unfortunate. The Monarchs are in a big crisis and have decreased in numbers dramatically. I blame Neonicotinoid pesticides, genetically modified crops, Round-up ready crops that have wiped out milkweed in huge areas of agricultural fields, severe loss of habitat...both in the U.S. and Mexico. The fact is, we need to provide the Monarchs with more milkweed (their only host plants) during the times of year when they are here to reproduce. Also, the Monarch butterflies and especially the caterpillars are sensitive to pesticides and every bit of restraint in that matter makes a huge difference. There's been a groundswell of demand among those who want pesticide-free milkweed to find a reliable supply. But still, most nursery milkweeds being sold have systemic pesticides applied at some point before being offered to the public...systemic pesticide doesn't wash off and will kill the caterpillars. And I might add, if you go to nurseries to buy milkweed, you're unlikely to find any milkweed except Tropical Milkweed. Now, in the town of Medina, there's a nursery where you can find native milkweeds that are safe for Monarchs. It's called Medina Garden Nursery. http://medinagardennursery.com/about-us/ Or you can get seeds and grow your own milkweeds. I've had Monarchs come by three times this year and lay eggs on my milkweed here. I have native Texas Milkweed and Antelope Horns, which are perennials. There are many native Texas milkweeds...they're just harder to get. I also grow Tropical Milkweed and have never had a problem with Monarchs lingering to spend the winter here. It is an annual in most of the country, but can survive winters when temps don't get very low. Since I live in the hills where it's a bit colder, they will often die here if not protected. I haven't seen any Monarchs yet this fall, but the peak month for fall migration is usually October, so they're probably coming through. There's just much much fewer Monarchs than there used to be, so you might have to really watch carefully to spot any. They need our help. The Monarchs that are just passing through headed to Mexico will need to stop and find flowers for nectar, food to help them on their way. There are also usually some reproductive Monarchs headed our way in addition to those. They will use milkweed to lay their eggs on. That way, any of their caterpillars that survive and become butterflies will increase the numbers of Monarchs that head to Mexico to overwinter. https://monarchbutterflygarden.net/raising-monarch-butterflies-ebook/http://www.washingtonpost.com/news/wonkblog/wp/2013/12/03/why-are-the-monarch-butterflies-disappearing/ http://www.cbsnews.com/news/monarch-butterflies-drop-migration-may-disappear/ http://www.monarchwatch.org/

From what I read around the internet, it makes the Monarchs stay because they have food in the winter time. Here are some pros and cons, http://monarchbutterflygarden.net/is-tropical-milkweed-killing-monarch-butterflies/. I don't know if I have the patience or the time to put the seeds in the freezer for 2 or more months. I probably can do the 2 weeks. I have some tropical planted now, about 1 to 2 inches, and I bought some at HomeDepo and Galloway, but for the amount of Monarchs I get, the 10 plants I got is not going to be enough. I also got 1 big and 2 medium of the swan milkweed, which they eat already, and a giant milkweed that's not too big now. The tropical milkweed we just throw in soil and it comes up, never did anything to it. Now I'm reading the directions on the back of some seeds I bought, it says, soak seeds in hot water for 24 hours, then sow seeds on soil surface at 70f and water. That I can do now, need to have more seedlings going. every time I go get a plant, it's 4 to 5 dollars each for smaller ones, and more if they're bigger ones. The swan milkweed I got seeds, and the instructions are the same. Going to put them in water now.