Adding to what’s already been discussed, I’d urge some skepticism about shortcut methods with Trillium seeds. Gibberellic acid and scarification haven’t outperformed plain patience in well-designed trials, and sometimes they’ve actually dropped viability rates (see Cullina’s work at the New England Wild Flower Society). Double dormancy is hard to cheat. I’ve had my best results with classic two-year cold/moist stratification, buried in mesh pots in leaf litter, mimicking wild conditions as closely as possible.
Re: division-avoid working in spring when buds are swelling; mid/late summer after seed drop is much safer. Disinfect knives between every cut, not just per plant. Trillium rhizomes are notorious for spreading Botrytis and Fusarium fast if you skip this. And yes, any organic-rich woodland mix is better with a scoop of duff from an established patch, since the mycorrhizal component seems vital (there’s ongoing debate, but all my healthiest divisions get locally-sourced duff).
Empirically, slow and cautious wins here-“doing less” and copying nature is underrated.
