Dahlia (Dahlia variabillis)
This dainty perennial flower comes in a sorts of lovely colors. As they grow, Dahlia's form a tuber (like Four O'Clocks from seed do) that you can dig up in fall and replant next spring if you live north of their hardiness zone of 7-11.
How to Grow Dahlia from Seed
Dahlias are tender perennials that do best in full sun to partial shade and thrive in a wide variety of soils. Single Mix Dahlias are easy to grow, but can take a full season to mature to their full flowering potential
For best results, expose seeds to moist, cold conditions (stratification) prior to sowing. For cold stratification, place seeds in moist potting soil or sand and store in a refrigerator for 4-6 weeks. After stratification, sow seeds in containers or direct seed outdoors after the danger of frost has passed. Sow seeds 1/8-1/4" deep and 6-8" apart. Optimal soil temperature for germination is 65-80˚F. Seeds will sprout in 10-28 days. Thin seedlings so that mature plants are 24-36" apart.
Seeds can started indoors and also be direct sown outdoors in the fall where they will stratify naturally and germinate the following spring.