These giant coleus are the great-great-great grandchildren of a plant I bought five years ago. Each fall, I snip several cuttings and keep them in a vase of water all winter, where they grow masses of roots. In late spring, I stick the tiny shoots in soil, where they grow, and grow, and grow!
It’s important to share these with friends! One fall, I forgot to take my cuttings and let the plants freeze. Luckily, though, earlier in the same year I had potted up two cuttings for a good friend. When she paid me a visit the next year, she asked me if I would enjoy some of the cuttings she had taken the previous fall. Little did she know how happy I was to receive them and keep the lineage going!
Giant coleus pair well and share similar requirements with impatiens. All of mine get a few hours of morning sun each day. The light helps them develop rich, vibrant color. I kept one in fairly deep shade one year, and it remained pale green for the duration. They enjoy a lot of water, but recover nicely if you forget and let them wilt. I frequently pinch back the inner leaves of the rosette to encourage branching, and sometimes even pluck of some of the larger lower leaves for that purpose as well. If a flower spike should shoot up, it gets ruthlessly clipped too.
Before the first frost (at least most years!) I take numerous cuttings for next year. Mine are generally about six inches long. I strip all but the top leaf rosettes and stick them into a vase of water. Within two weeks, roots form. If the cuttings themselves grow and get leggy, I’ve found that I can take cuttings of the cuttings and successfully root them as well.
I heartily recommend growing and sharing these giants in your gardens!