Since the single flowers are larger the implication is you have another, single-flowered form mixed with the double in the same clump. Otherwise one might assume the double had reverted to single.

I'd rather have the plus-sized single type so I'd just remove the double-flowered portion.

I have to agree with bboy. I've always thought the single version more elegant and attractive than the double, not to mention far less common (over here at least).

i disagree with both ...

it is stunning in mixed form ... why not enjoy both ...

i would not call it invasive.. popping up everywhere ...

i would call it somewhat clumping ... and a bit meandering ...

what moves around is very shallow rooted.. and can usually be grabbed and pulled out.. almost back to mom ...

and then shared with friends...

at the old house.. a neighbor had them as an understory plant to very high pruned trees .. bright with good soil but shade.. they where very whimsical ...

i brought some of those to the new house .. and planted them in mineral sand.. in full blistering sun ... with mulch ... and they survive.. but they are pretty ratty looking by late summer.. are about half the size.. etc ...

yours may or may not like the spot you have them in ... but you will be hard pressed to kill it ... move it in fall.. if you decide its in too much sun ... [proper water is probably my biggest problem ...]

ken

Thanks for the info everyone. Although I was at first disappointed to see that it wasn't what I paid for, I went out again this morning and really do like the single flowers. But as Ken suggested I am probably going to let it go with the mixed look.

Ken, this is on the north side of our house and gets only a few hours of morning sun. I hope it does well (but not too well, lol!) as I absolutely love the vibrant color of this one!

Vickie

Perhaps, if a single flowered plant is not actually mixed in, you have a 'sport'. A mutated cell became a branch, over time. The double-flowered sort probably came as a sport on the normal sort, somewhere, sometime long ago.
I agree that the single bloomed branch is elegant.
Kerria seems to thrive in light shade from tall trees.

as per boggy.. then take 'propagation of kerria' to google.. and find out how to root each piece .. and see if you can 'capture' both ... or either ... just to experiment ...

they are not grafted plants.. so its possible.. the question is just how easy .. and whether you need greenhouses.. misters.. heat mats ... etc ....

ken

Kerria is very easy to propagate. You can just trace a stem to the ground and pull hard to get a rooted piece. Then just transplant where you want it. No fancy gear required.

My daughter just asked me today if she could get a start of it. So I guess I will have to try to get a start for her.

Thanks for the help with propagation.

Vickie