Each fall, before I shut things down for the winter, I take cuttings of the plants I most want to perpetuate in my landscape for another year. These peperomias fit into that category, and I really need more for some things I have planned come spring.
Not all plants root easily from cuttings. Coleus, impatiens, wax begonias, firebush and vining tropicals normally do. Copper plants, by comparison, have always been more challenging for me.
For all of these, my peperomias included, I use a mix consisting of a lightweight potting soil mix and equal amounts of horticultural grade perlite. I also add 10 percent expanded shale for a little added ballast. These are being rooted directly into 4-inch plastic pots, and from there, I'll transplant them sometime before Christmas into 6-inch terra cotta pots. I'll put at least two of these pots into each of the larger containers, and they'll be 10 or 12 inches across by spring. I use these plants in wall planters, also in plant stands and even to line beds along walks. I'm sure I'll be rooting more than just these, but I need to get busy!
For the record, cuttings of most of the plants you might want to save should be 3 or 4 inches long. Strip off the bottom half of the leaves. Use a thin stick or pencil to make a hole in which you can insert each cutting into the wet potting mix. Use your fingers to pinch the potting soil up around the stem. As soon as all the cuttings have been struck, water them again. For some other, less durable cuttings I took about a month ago, I laid a sheet of dry cleaner's plastic over them to keep the humidity up. These peperomias began to form roots within 15 to 20 days.