After a month or two, we had a healthy little bush with a few buds. And not long after, those buds unfurled to reveal scarlet blooms with delicate ruffled edges.
Our hibiscus has been blooming for months now, and even though the weather has turned crisp, we can count on a few more beautiful flowers every morning. The plant I was so determined to trash is now flourishing.
I suppose our hibiscus doesn't technically count as a volunteer, since it was planted by the previous homeowner -- but still, it's such a lovely surprise to have something so beautiful grow up in the last place you'd expect!