Being annuals, there is little point in attempting to grow cornflowers from cuttings, even if it worked, which I doubt, since they will die after flowering. The cuttings would be the same maturity as the parent and genetically programmed to die. But perhaps you could post a picture so we can ascertain exactly what sort of cornflower this is. Perhaps yours are not the annual Centaurea cyanus but the perennial Centaurea montana?

post a pic or 3 ... leaves with scale ... stem.. and whole plant ...

and include big city location ...

we need a specific ID on the plant.. before we can give you advice ...

the word cornflower might be a regional name.... and to provide you good info.. we need to ID it ...

the cornflowers i grow.. in my MI ... barely make it thru august.. before they are so spent ... they need to be pulled out after spreading some of the billions of seeds on every plant ... so as to generate then again next year ..

ken

Thanks for your reply. I’m in Sydney, Australia, which I think is zone 10 - warm temperate. This plant was from a semi-dwarf polka dot seed mix. All the other plants from this batch flowered in spring and finished as the temperatures rose. We’re now in full summer. This one is still around, but as I said, it never sets seed. i’m hoping that if i can strike a cutting, I’ll be able to keep the plant going indéfinitely. I’ve been able to do this with a sterile nasturtium that is now in its tenth-or-so year. Here are some pix.

Nasturtiums are perennials which root along the stems and are very easy to propagate. They’ll keep going even when consigned to the compost heap. Centaurea cyanus is a true annual, quite a different beast. All you can do is try it. But you’ll be fighting biology. Can’t I see some seed heads in the photo?

I have succeeded in growing zinnias from cuttings. I use rooting hormone and humidity domes.

Those things that look like seed heads are just dead flowers that don’t develop into anything.

yep thats them ... 30 years in my garden.. since i planted seeds way back when ...

second pic here: https://duckduckgo.com/?q=Centaurea+cornflower+seed+pods&t=ffcm&iar=images&iax=images&ia=images

break them open and strew them where you might want them .. unique silvery seedlings are easy to ID ... and can be easily moved at 2nd leaf stage.. perhaps on a rainy day ...

i also think i see a seed pod or two on the first pic.. but it is pretty far away ...

when the plants get ugly nearing fall ... you can just rip them out.. and lay the whole thing where you want seedling in spring.. and it will self sow.. but not all that aggressively ...

ken

Thanks for everyone’s responses. here are a couple of photos showing my situation. this is as close this plant gets to setting seed. The seed pods look normal for a while and then just dry up in a closed shape. As you can see in the second photo, the pod is empty. I’ve saved the seed of cornflowers before but believe me, this one produces no seed at all!

Here’s a close-up photo of the would-be seeds from another ripe pod. They’re all empty and flat.