A good stand of larkspur was an elusive prize for me until I tried a little trick a fellow gardener suggested. She told me to chill the seeds in the refrigerator for about a week before sowing them to improve the germination rate. It was a great tip that has made it possible to enjoy this delicate bloom every spring.
In my zone 7 garden and other mild winter climates it is best to sow larkspur in mid-fall because the seeds need cool soil temperatures to germinate (50 to 60 degrees F). I try to get the seeds in the ground before November. If you live in a region where winters are cold and the growing season is short you are better off planting pots of larkspur purchased at a garden center in spring rather than trying to grow them from seed.