Look for seedlings at your local nursery in spring. However, if you want to take advantage of the broad range of flower colors and forms available, comb the seed catalogs and start from seed.
Choose a sunny planting site with rich, well-drained soil. Work in plenty of compost or sphagnum peat moss.
Sow seeds indoors 6 to 8 weeks before the last frost date or directly in the soil after your region's last frost date.
Place seedlings 6 to 12 inches apart after your region's last frost date.
Pull plants up after the first frost.