Purple, Showy, Spider, and Poke Milkweed

[pjvanee]

Does anyone have any experience growing Purple Milkweed (Asclepias purpurascens), Showy Milkweed (Asclepias speciosa), Davis Showy Milkweed (Asclepias speciosa 'Davis'), Spider Milkweed (Asclepias viridis), or Poke Milkweed (Asclepias exaltata) in a garden?

I need to know if they clump or spread, how much shade (if any) they will tolerate, and how far apart to space the plants. I think the Showy milkweed may be too spreading for my smaller gardens, but I could not find any information on whether or not the Davis variety has a similar habit.

Any information on any of the above varieties would be greatly appreciated.

[Paul Cherubini]

All those species eventually spread via underground rhizomes that branch out and spread. It takes years for the spread to be a major concern, however, so I wouldn't worry too much. I've planted speciosa and the Davis speciosa variety close together - just an inch apart. They do OK in partial shade but grow faster in full sun. I havn't had a significant problem with spreading.

[dandjtaylor]

I have about 20 purple MW among my 100 plus MW's. They grow much like Swamp. Mainly out from the center root ball. But they do send out an occasional spreading rhizome like Paul says. But nothing like the invasive common. They do put out a beautiful bloom globe though.

D

[Mona Miller]

http://davesgarden.com/guides/pf/go/110313/
Pallid Milkweed, Davis' Milkweed, Humboldt Mountains Milkweed, Cow Cabbage
Asclepias cryptoceras

http://davesgarden.com/guides/pf/go/81058/
Purple Milkweed Asclepias purpurascens

http://davesgarden.com/guides/pf/go/62479/
Green Milkweed Asclepias viridis

http://davesgarden.com/guides/pf/go/54079/
Showy Milkweed, Greek Milkweed Asclepias speciosa

http://davesgarden.com/guides/pf/go/54078/
Poke Milkweed, Tall Milkweed Asclepias exaltata

[pjvanee]

Thanks for all the milkweed links and the sharing of your personal growing experiences. It is getting harder and harder for me to find milkweed in the wild, so I am looking forward to planting these new varieties in my gardens this year. Because I am working hard to get milkweed in as many locations as possible, I started enough plants to share with friends.

[Mona Miller]

Wow, you are on a roll. "Got Milkweed!"

[lvtgrdn]

Hi,
I just got several kinds of milkweed, one of which was the purple kind. I got a tall and a short green milkweed plant. After looking at the link to Dave's Garden, I see that green milkweed is not hardy to my zone, so I"ll have to collect some seeds and figure out how to store and plant them.

Somewhere on the Monarch Watch home page, there are links, and one of them is for milkweed information. I'll have to go back there, too, to look up the ones I bought.

[Mona Miller]

Where did you purchase your plants?

Here's the linck for the Monarch Watch milkweed page:
http://www.monarchwatch.org/milkweed/guide/index.htm

You can create a micro climate by planting plants near rocks and structures. Placing some extra mulch in the winter also helps.

[lvtgrdn]

I had gotten a couple white blooming swamp milkweeds from Earl May Garden Center. I read somewhere here that the plants from garden centers or places where chemicals were used on them should be washed before the caterpillars eat them. We don't have caterpillars yet. Is the rain sufficient?

The other plants, including a pink swamp milkweed, I got from the UNL Arboretum's plant sale. They are pretty small, but I figured that they would just be coming up here anyway.

Thanks for the link to the milkweed information.

[Mona Miller]

Some of the pesticides are inside the plants and don't wash off for ages. Even some organic pesticides can be very long lasting. If your caterpillars get sick, then you will know for sure that your plants have been sprayed with something that doesn't wash off easily.

The caterpillars usually spit up green if they have been poisoned.

[lvtgrdn]

I think I better call the garden center to see if they've used chemicals on the plants.

[Mona Miller]

Supply and demand will be what puts unsprayed milkweeds in nurseries. Last year, I purchased plants from a nursery that wasn't suppose to spray their plants. Part of my caterpillars died before I knew what was wrong. I did communicate with the nursery and they contacted the grower that they purchased the plants from. They had sprayed something for aphids. Many teachers go to that nursery to purchase milkweeds for their school programs. The nursery manager took my concern to heart and found milkweeds that hadn't been sprayed.

[gstell]

Showy Milkweed and Common Milkweed are very closely related. A. speciosa being the western lookalike of A. syriaca (common milkweed). Their growth habits are nearly identical producing vigorous rhizomes and if left unchecked will produce clones 20-30 feet in diameter. Both require (prefer) full sun, and fertile soils. Where the two species meet in western Kamas around Topeka they readily hybridize. We usually think hybrids as vigorous, but these are anything but and to not spread outside of the original locations.
I tried to grow A. speciosa at my place in Auburn, NY but failed. The plants never thrived and eventually died. This as I understand it is typical when moving an Asclepias out of it normal range. Even saying that a friend has told me he knows of a naturalized stand in the Ithaca area. It’s a fun plant and a beautiful flower.
A. purpurascens physically looks like Common Milkweed but typically shorter. It wants rich soils and plenty of moisture. However it will tolerate and often grows along hedge rows provided partial shade. It also spreads with rhizomes, but not vigorously. The clones rarely expand beyond 5 feet in diameter. A. purpurascens is listed in NYS as endangered. A couple of years ago I found it in northern Cayuga County.
Gary Stell
Auburn, NY

[Paul Cherubini]

I tried to grow A. speciosa at my place in Auburn, NY but failed. The plants never thrived and eventually died. This as I understand it is typical when moving an Asclepias out of it normal range.

Gary, I didn't have any problem growing syriaca here near Sacramento, Calif. that grown from seed collected in Minnesota and Missouri. It grew an amazing 6-7 feet tall after 3 years! I like to interplant speciosa and syriaca because the former blooms earlier, hence I can have blooming milkweed plants in my yard over a longer period of time in the summer.

[kcned]

In reference to green milkweed and hardiness, here in KC we are in zone five and it wasn't that long ago that it got down to minus 23. The green milkweed, short and tall didn't blink and were fine, even growing out in the open on a limestone bluff. Nice pretty plants and will bloom when the early ones are done.

[Mona Miller]

Can you give us a latin name?

http://www.monarchwatch.org/milkweed/guide/index.htm
This is the milkweed guide from Monarch Watch.

[cocoonage]

Still looking for the latin name...