When is the best time of year to plant sunflowers in North Carolina?
Sunflowers (Helianthus annuus) are relatively easy to grow. Sunflower seeds can be sown outdoors any time after the danger of frost has past (this should be early or mid April in Nashville).
Choose a location with well-drained, rich soil. A sheltered location is preferred if you want to avoid staking, but sunflowers need full sun to flower well. Sow the seeds in 1 inch deep holes about 12-18'' apart. If you stagger sowing batches of seed about 2 weeks apart then you will get a continuous display of flowers in the summer.
In hot weather, water the plants well about once a week but do not allow the soil to get soggy. Note that there are numerous cultivars of sunflowers available with a range of plant size and flower characteristics, The Seedsavers website has an extensive list.
Courtesy of NYBG Plant Information