Just clip off some cuttings with a little bit of stem and a few leaves then drop them in a jar of water. I like using glass jars to watch the roots form. Sticking them in water isn't even necessary as they will root fine in moist soil. Once spring arrives either plant your whole coleus plant back in the garden or take cuttings to make more plants to pot outside. Coleus is one of the easiest plants I know to propagate!
If you don't want to mess with cuttings this time of year and the mess that ensues with potting them up later (of course if you are reading this than most likely that doesn't bother you and you are thinking "mess what mess?") collect the seed. Just let the plants go to seed and run your hand along the brown flower stalk with an envelope underneath. Lots of little tiny seeds should fall right in to the envelope. One word of warning though, don't expect the seed to come true to the coleus from which you harvested the seed. Many of the coleus plants we buy in the stores are hybrids which are a mix of other plants and will most likely revert back to one of the parent plants or become something new. Who knows, it might be worth trying just to see something different! To guarantee the exact same plant as the year before you have to propagate vegetatively and not through seed. Yep that's right, it's best to clone them!
Besides, don't you think these coleus cuttings would brighten up any room?
The only drawback is for those of us who think about the dollars spent vs. effort applied idea. A six-pack of these beauties costs less than $2. I bought 4-6 six packs this past spring and planted them along our rock border in the side garden. So I guess if you don't mind spending a few dollars each year propagating coleus over the winter might not be the way to go, but if you are like me and like to save a few bucks than maybe it is!
Will you be taking any cuttings this fall to over-winter indoors?