Purple cornflower, or bachelor's button (Centaurea cyanus), is native to Europe and naturalized throughout North America. Originally blueish-purple in color, cornflower is available in violet, pink, white and red. Plant purple cornflower seeds when the soil temperature warms to 60 to 70 degrees F. Cornflower seeds have an 80 perfect success rate, so plant more seeds than wanted to ensure success.
Select a full-sun spot in the garden for the purple cornflower seeds, which also will grow in light shade if necessary.
Turn over the soil with a small trowel. Pull out weeds, rocks, sticks or other debris.
Dig a narrow trench 1/8 of an inch deep with a small trowel. Scatter purple cornflower seeds in the trench following the spacing directions on the seed packet. Cover over the seeds lightly soil.
Water the seeds until the soil is moist. Keep the soil moist at all times until the seeds germinate, typically within seven to 25 days.