Watch out for the wood poppy if you have ideal conditions for it - it has a reputation for rampant spread. But, apparently it does not like too much light or dry soil conditions and is under threat in its native places due to things like logging/forest clearing. Hopefully those very specific growing condition requirements would make it easier to control (i.e. by eliminating shade so it couldn't grow....)

We just got a mukdenia this sping so have no real experience with that but it looks interesting. (And your post reminds me that I should go check how it's doing - it's in a spot I don't visit very often....)

I grew mukdenia rossii from seed in 2010 and up to now it has proven hardy for me. So far I'm loving this plant. Someone told me to take notice of the flowers and this spring I remembered to do so and took a picture. In the fall the large maple shaped leaves turn a lovely soft orange shade.
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Thanks so much for that picture north53. Excellent.

In what conditions ie sun and moisture do you grow your mukdenia?

One of the advantages of starting perennials from seed is that you can try them in different locations. I have several planted in the shade of mountain ashes. So far they are thriving there in spite of the root competition that challenges other plants. The others have better locations, but all are in the shade for the most part. One gets morning sun, and one gets evening sun. It's too soon for me to say which will be the best spot. The flowers are tiny, but I could see them from across the yard.

'woody'. it is interesting that it can be invasive (under the correct conditions) and yet still be endangered (in certain areas).

I see there is another wood poppy known as the "Chinese Wood Poppy" (Stylophorum lasiocarpum) that is advertised as less aggressive. I am going to pick up one of these plants and with each planted I will compare and contrast.

(And your post reminds me that I should go check how it's doing - it's in a spot I don't visit very often....)

That is a sign to me that your property is nice and big 'woody'...I am jealous ;).

For me, Stylophorum diphyllum is very well behaved. It does set a good number of curiously ornamental pods filled with copious amounts of seed which is carried off almost instantly by ants who are attracted to the elaiosomes. I have not noticed any seedlings yet, and there are no seedlings to be found around my neighbors' more established plantings either.

I do wish mine would multiply, so this year I have been intercepting the pods as they start to turn yellow, right before bursting open. I have been scratching the fresh seed into the soil where I hope some will germinate in the spring.

I have read that even the small seedlings are easy to identify and remove. This plant will not regrow from root fragments left behind once pulled up.

There are many other plants called wood poppy or celandine that can be invasive. The most notorious are Chelidonium majus--a European import that can look shockingly like Stylophorum diphyllum--and Ranunculus ficaria.

Here is a link that might be useful: Confusion over Celandine--Scott Arboretum

rouge - it's not that the property is big but that the spot the mukdenia is in is damp (LOTS of mosquitoes!) and there are roots of a pussy willow tree that I tend to trip over when trying to get down there! We bought the mukdenia at the RBG plant sale in early May. I was still in a cast at that point so I told DH where to plant it - I wasn't entirely sure he fully understood where to put it.... I haven't wanted to risk tripping over the tree roots so I've not gone down to see what's happened to the mukdenia. I just sent DH down to take a picture of it for me. He had trouble finding it at first since he planted it too close to a hosta and it was hidden under the hosta leaves! Clearly it'll need to be moved next spring. But it seems to be doing OK:
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I have noticed a downside to these plants. They are one of those perennials that can't endure any frost. This spring we had a very late heavy freeze and since they are early risers all were severely impacted and were ugly for a while, though they quickly grew new foliage. And of course, in the fall, Their attractive colour transition ends once there is frost. I still like them, but found this disappointing. They are like hostas in their frost intolerance.

Z1b ?!

I can understand why you would want plants that are somewhat "frost tolerant" ;).

(Any idea what the Average Date of the Last Spring and First Fall Frosts for your location?

For my location it is about the 2nd last week of May and the second week of October).

just curious....why is a two year old being revived with a new subject?

North53, when it comes to foliage frost tolerance, I've been rethinking some of my perennial placement, especially within beds nearby to the house. I'd rather select plants capable of enduring hard frosts to carry on looking good until covered by snow. Case in point, choosing semi evergreen ferns over those that turn black with the first nippy morning.

Just an observation: You'll get more responses if you post your questions in a new post. People look at a "stale" (old) date and aren't as likely to read to the bottom to see a new question or issue.

just curious....why is a two year old being revived

A good thread is never too old ;).

There can't be many zone 1 gardeners that frequent this forum.

north53 I would love to hear of your favorite perennials that do well in your garden. (If they can make it there they can make it anywhere ;))

Absolutely not annoyed. Sometimes when people come across a GW topic or question on google etc,; they don't see that a post may be 5 or 10 years old. They spend time answering a question, sometimes at length, asked by someone who hasn't been around for years.

Rouge....yeah, like the "Dog in Elk" urban legend....it resurfaces every few years and disables another generation in laughter.

But seriously, I'm sure you've seen cases like I mention above. Being practical, and perhaps a bit nostalgic, I don't remember this happening with the "old" GW. Some little thing changed in the formatting or archiving that makes it easier for people to pick up ancient threads and not to notice a date.

Also, posting a new question at the end of an existing thread doesn't get the question the respect it deserves! I don't get upset about hijacking like some do, but it doesn't work for the poster so well.

Finally, (hijack) I often like your questions and photos very much! Glad you're around.