Have you tried the seed exchange forum here? There should be many people willing to trade with you.

Certain milkweeds are harder to grow.
In my experience, asclepias incarnata and asclepias curassavica were easy to grow without cold stratification. Asclepias physocarpa needed cold strat. And asclepias fascicularis didn't germinate for me at all.

I don't know if I would plant wild milkweed in my beds, though. I'd be too paranoid that it would take over.

This is my first year planting milkweed so unfortunately I have no asclepias to share.... yet.

Here is a link that might be useful: Milkweed info

You can order Tropical Milkweed plants (asclepias curassavica) in bulk fairly cheap. It's an annual rather than perennial but Monarchs love it for laying eggs and it's very pretty. I can't recall the Monarch website that sells them cheap. Maybe someone else will know. I think they were less than a dollar apiece if you order a lot.

Monarchs like Swamp Milkweed (asclepias incarnata). It's perennial, but that one might be difficult to keep watered in Colorado.

They will use Butterfly Weed for laying eggs (asclepias tuberosa) but it's not their favorite. Very pretty though, easy to grow from seed, and perennial.

Common Milkweed (asclepias syriaca) has large leaves but it's an aggressive spreader and might eventually be the only thing you have in your garden.

There was a post recently about Purple Milkweed (asclepias purpurascens) which also has large leaves but supposedly not as aggressive as Common Milkweed. I'm giving that one a try this year.

I would suggest ordering some Tropical Milkweed plants for this year and also starting some milkweed from seed that will be perennial. They're pretty easy to grow from seed. Winter Sowing works well for them (starting outdoors in covered vented containers) and it's inexpensive.

Here is a link that might be useful: Winter Sowing Forum

A good mail order nursery for milkweed plants is Pine Ridge Gardens in Arkansas. She has all kinds of MW. I have found it is easier with Purple MW to purchase plants. It takes some MWs several years to get established and bloom.

Hi Wild turnip, welcome to the world of butterfly gardening.

You are a little late to start SEEDS for this season so I would think about getting some milkweed plants and planting seeds outside this fall.

Here's a vendor you can get cheap tropical cuttings from:

http://www.butterflyworkx.com/tropical-milkweed.html

and you probably won't find milkweed plants cheaper than this on OR offline: http://stores.ebay.com/dogwooderitternet/_i.html?_nkw=milkweed&submit=Search&LH_TitleDesc=1&_sid=22706085

Good luck, Tony

Here is a link that might be useful: Milkweed Plants

I have loads of A. incarnata and tuberosa seeds you can have for postage. I've had a butterfly garden for years and recently moved to a shady yard, so I don't have space for much milkweed. I already wintersowed several containers, and they've sprouted, so I can give away all the seed I've saved from last year. Do you need other butterfly friendly plants? How much space do you have? The Monarchs like to have nectar sources in addition to the host plants for the caterpillars. I'll send you an e-mail.

Martha

Your e-mail is not an option on your member page. You can send me an e-mail if you're interested.

Martha

Turnip, I have 2 swamp milkweed plants that you can have for postage, and I could also send along a bunch of tropical milkweed seeds. Email me if you're interested.
Cathy

I forgot to mention that these will get big and bloom this year, so then you will have seeds to start more plants next year. I had them growing in the garden last year. It's the last of my swamp milkweed plants, as I once had 100 and gave them all away because of having to downsize. These two were volunteers. These plants aren't aggressive like Common Milkweed if you're worried about them spreading via rhizomes...they don't.
Cathy

Wow. Am completely blown away by all the great responses. Will look in detail tomorrow. Thank you!