Hi Venice.. I dont grow one myself but you may find some interesting info on the link below...

Best if you type *How to propagate Romneya * into Google or whatever search engine you use there are 312 links there so plenty of reading on how to go about it.. Best of luck.. Misty

Here is a link that might be useful: Romneya

Just found your posting so hope you are still checking in on this thread.

Romneyas can be propagated by digging up those suckers that are spread all over the place. They are shrubby perennials so you propagate them at the optimum time for any perennial. Best done in late winter/early spring when they are starting to show some signs of life. For every four you lift and pot, you might lose three of them. Best to choose bits at least 1 metre away from the original plant.

The key to success is doing it at the right time of year. You can wash off the soil from the divisions by soaking in a bucket of water for a few minutes. Don't fuss too much about a bit of soil still adhering to the root zone. Then just pop the Romneya divisions into a good quality potting mix that does not contain those water saving crystals. One that contains a high proportion of sand is good, or you could add some coarse washed sand to the mix.

Many of our so-called "Premium" potting mixes now available are appallingly bad as they consist of half rotted bark and decomposed coal. They continue to compost down while the poor plant is trying to grow in this horrible medium. Often the cheaper potting mixes are actually better as you can choose to add water crystals or granulated fertilizer to suit your needs. I never buy any potting mix that does not contain a solid proportion of sandy loam. My favorite comes in a yellow bag, made in Sydney and costs under $5 per bag from Bunnings. I've even found it on special for $3. I add a little sand or a little extra real peatmoss, maybe some water crystals and/or osmacote as well, (but not for a Romneya), to this potting mix depending on what I'm planting in the pot. When you pay $8-9 per bag for potting mix from well known names, you are paying for a lot of their advertising budget and crappy contents.

Do not over water the young Romneya divisions. They like good drainage. In other words, don't kill them with kindness. Put the pots in the spring sunshine, not in a shade house and only water when the potting mix is almost dried out.

As you get the hang of it, your success level will rise until you will have success with three out of four divisions. More Romneyas are killed from over watering and over fertilizing than from any other reason.