From my very limited success with Trillium seed (except rivale which always seems reliable) it seems to me the important thing is never to let them dry out so the "under the soil" thing Ian uses would most likely be best. Having said that, it seems some at least can just sit there until the conditions are right. I have some coming up now, sown 7 or 8 years ago, and they too have been covered, with eucalyptus leaf litter which doesn't rot but does make a wet mat, so I suppose that's more or less the same as putting some compost on top of them, enough litter having accumulated, except the litter is on top of the grit.
