Can you put decorator rocks on top of concrete?

sure you can - here are some ideas

https://www.remodelaholic.com/6-ways-make-concrete-patio/

Hi Marie! A concrete patio is a perfect base for any kind of stones or concrete you might want to add to it. Here's some more info: https://www.baysidepavers.com/blog/2018/5/26/what-to-know-about-installing-patio-pavers-over-concrete

As long as your patio is thick enough to support the weight of "big" rocks. People have different ideas of big so if you are talking boulder size that's different than bowling ball, both would be big to me. Just make sure you have a sufficient foundation. If you want to secure in place, Loctite's Power Grab is a great product. It is slow setting but works very well on stone and in an outdoor setting.

I think it sounds like a great idea!

Our cement patio was constructed in sections, over time there has been some settling. The sections became uneven and dangerous tripping hazards. It was pricey for us to fix it. I would make sure your cement footing is solid before adding large rocks.

Oooo, take a look here at what they did to their patio, beautiful, these are seriously large rocks:

https://www.pinterest.com/pin/32510428537074177/