10/29/2026
“Ask a Master Gardener” often gets questions about why seeds that have been carefully saved from last year’s perennials are not germinating after being planted in the spring. Many perennials require a cold period, or stratification, to germinate. Seeds that have not been given a cold period and planted in the spring will just sit in the soil but may germinate the following year.
Per the U of I Extension, “seed stratification is a temperature-change treatment that breaks seed dormancy and signals seeds to germinate at the proper time.” https://extension.illinois.edu/blogs/good-growing/2022-01-27-seed-stratification-what-seeds-require-cold-treatment This makes fall an ideal time to plant some seeds because winter’s cold temperatures and moisture provide what the seeds need to germinate the following spring. If you have ever planted Rudbeckia, Milkw**d, or Coneflowers, you may notice that they spread all by themselves, no need to reseed as nature takes care of it. Here are some seeds that can be planted directly in late fall: Poppy (Papaver), bee balm (Monarda), columbine (Aquilegia), coneflower (Echinacea), delphinium, black-eyed Susan (Rudbeckia hirta), and milkw**d/butterfly plant (Asclepias). If planting seeds in a bed, wait until after the first hard frost to avoid seeds germinating too early. There is no need to water or fertilize!
If you have seeds and don’t want to prepare a bed this fall, you can provide stratification inside using your refrigerator, mimicking the cold treatment they would get outside. Oklahoma State University has a good step by step on how to do this using milkw**d seeds but can be applied to any seeds requiring stratification. https://extension.okstate.edu/fact-sheets/native-milkw**d-germination-guide As mentioned in the article, if you are doing this indoors, the amount of time required for stratification varies. This information should be on seed packets if you buy seeds, or you can research on the internet. Native plant nurseries are an ideal source for this information. For best results, find a source in your geographical area because this will take into account your climate zone. The Xerces Society has loads of resources for purchasing both native seeds and plants: https://xerces.org/pollinator-conservation/native-plant-nursery-and-seed-directory Also within this link you can find lists of pollinator plants for your state, providing information on plant form, soil, sun, water needs, and bloom times. If you want to try starting native seeds, this is an excellent place to start for basic information. Cornell also provides nice information on saving and treating perennial seeds: https://blogs.cornell.edu/biocontrolbytes/2024/03/19/growing-perennial-wildflowers-from-seed/
A word of warning if starting perennials by seed: they should germinate the first year, but it may take another year or two before they flower. If you are anxious to start a pollinator garden, starting with a few transplants and then supplementing with your seedlings in the spring will provide a healthy resource for pollinators after a few years. Fall is a great time to transplant perennials as well. Cooler temperatures, more rain, less w**d pressure, and fewer pests make it easier for them to establish a healthy root system going into winter. Unlike planting seeds, you will need to make sure plants get adequate water to develop roots.
If you are collecting seeds yourself, you might wonder when are the seeds ripe and ready to be harvested? Seed ripening and timing of harvest will differ by species, environmental conditions and regional adaptation of plants. Signs to look for are seeds that fall easily from a plant, pods that lose their green color and begin to turn brown, seed capsules that are bursting open or stems that are brown, dry and brittle. Most seeds are ripe 4-6 weeks after blooming and will be plump, hard and dark in color. Seeds that are soft and green are not ripe. https://extension.illinois.edu/news-releases/harvesting-native-and-indigenous-perennial-seeds
