Which Flower Seeds Need Cold Stratification? Not All Do.

Cold Treatment: Only for Certain Perennials

Most annuals (marigolds, zinnias, petunias) and many perennials (hollyhock, hibiscus, coreopsis, dianthus, achillea, poppies) germinate without chilling.

Some lilies (e.g., Lilium formosanum) and other species with deep dormancy do require stratification. Always check the specific species.

When in doubt, a 30–60 day moist chill in the fridge won’t hurt most seeds and may help.