Jack in the pulpit will likely need cold stratification (most perennials from non-tropical areas do) and or other treatments. Seeds generally should be planted no more than twice their shortest diameter, except for some seeds that need light to germinate, which are then scattered on the surface. The light-needing seeds are generally very small. Very large seeds can usually be planted about an inch and no more as well. There are always exceptions though. Here's one protocol for seed raising -
http://npn.rngr.net/renderNPNP...
Planting them outside in the Fall can work too. But then you need to know what they (as seelings) and the weeds look like to separate them out.