Neither requires a cold period to germinate just sow the seed as before.
Do not expect the new plants to be exactly like its parents.

Is that based on plant species? What about dwarf marigolds or Catharanthus rosea? Do most purchased seeds not require that step? Sorry for all the questions, maybe you could direct me to where I could find the information.
Thank you for responding.

Marigolds, catharanthus (vinca) - no stratification necessary.

Stratification is one way of breaking down germination inhibitors more often found in hardy perennials, trees, shrubs - those plants whose seeds contain agents that repress germination, agents naturally eliminated through seasonal weather changes.

Sorry, missed the second part of your question earlier....busy with trick or treaters :)

There are some good online germination guides - Clothiers is great, take time to read through the sowing articles too.....if you were looking for a book, Making More Plants by Ken Druse is very helpful

Here is a link that might be useful: Clothiers Germination Database

Thank you very much for your advice. First time I have harvested my own seeds so I am excited to see what happens. This site is amazing!