First, you have to find rock seeds. Try for variety, a mixture of igneous and metamorphic, maybe some sedimentary. Local rivers are good places to look. They're even shaped a little bit like eggs.
Then you plant the rocks...after a few weeks you might notice that the ground is starting to ripple and develop bumps and hummocks. This is a natural progression as the rocks start to grow. But something is missing...
And we wait. You can even walk around the hummocks to see if any of the rocks are peeking though yet. But don't cheat and try to dig them out ahead of time. They might stop growing entirely.
I understand that some of our botanists and biologists are intending to...um...plant plants on these beautiful rocks. I have mixed feelings about this, but they say it will enhance the education of the children who visit the museum every bit as much as the rocks will. I guess time will tell.