Answer: Many of the wildflowers (and perennials) seeds require a cold period in order to germinate. If you try germinating them at room temperature for several weeks with no results, try chilling them at between 25 and 40 degrees for between several weeks and several months. You can chill the seeds in packets or in pots of soil. Another method some gardeners use with great success is to sow the seeds in pots in late summer or fall and leave them outdoors in a sheltered spot until they germinate in the spring. (If you do this be sure to protect the pots from rodents and other animals.)
Milkweeds generally require 3 months of cold stratification; most rue (Thalictrum) need about three weeks.
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