Wow, I've started mine from seeds about 5 years ago. They readily self seed and now they are popping up everywhere, including down the street and vacant lots. Just let them go to seed and leave the mature seedheads on the ground where you want them to grow. Yes the birds might snack on a few seeds, but they will still leave plenty to grow in Spring. There's very little you need to do.

You can try dividing the crown. Just slice through the rootball with a sharp knife. If you want to propagate, leave the seedheads on the plant until fully ripen and they turn brown and crispy. Wrap seedheads in a damp paper towel and into a baggie and refrigerate for about 3 months (this simulates winter and stratifies the seeds. They won't germinate unless they get the 'cold treatment'.). Start the seeds in a bright sunny window in peat pots around February. Bare in mind, that if this is a hybrid, you may not get exactly the same variety, but you may be pleasantly surprised.

if it is sensitive to cold I'd be tempted to lift it in the autumn after it has finished flowering. wash the roots clean and then split it into sections as you should be able to see natural sections. pot them up keep slightly damp until it gets really cold and keep them in a cold frame or unheated greenhouse until spring. when new spring growth starts, start watering them again, planting out in late spring.

They are cold hardy, you don't have to do anything. They don't like being disturbed.

I don't grow this variety so looked it up and the sites i found say it is hardy.

according to the RHS site it is a short lived but hardy perennial in the uk
link below.
https://www.rhs.org.uk/Plants/297981/Rudbeckia-triloba-Prairie-Glow/Details

I would have put money on these being a cross of triloba and not true from seed but low and behold! I just found them on Chiltern seeds! So apologies for not at first believing this fantastic plant is easy from seed. Never having previous luck with over wintering them i still think they are like an annual in u.k. but I'm in a new garden now so who knows i might be successful here.

Best of luck then Andrew. Much cheaper from seed!

Probably completely cold hardy, but not fond of cold, wet soil. In it's native habitat the winters are far colder than the UK, and the soil stays frozen all winter.

Thanks we are damp here in u.k. and i used to lose a lot of things so i ended up using lots of containers even with drainage and loam based soil but still would lose these other rudebekia were ok and thrived in containers. Huge difference growing stuff here what we regard as a successful over winter plant would be invasive in the states.