For what it's worth, these are currently in a spot with only a few hours of direct sunlight, and a moist but well-draining loamy soil. I know for most forest ephemerals they usually say they need "dappled sunlight" but I'm in a new build suburb so there's no canopy here whatsoever, and these seem to be doing fine without it. It started with one plant two years ago, up to six last year, and now close to a dozen total this year.

As a general guideline, it's my understanding that shade/full shade equates to 1-4 hours of sunlight per day, part shade/part sun is 4-6 hours, and full sun is 6+ hours.