Nothing brings on the brightness of mid-summer to early fall like the colors provided by sunflowers. Sunflowers (Helianthus annuus) have a wide skill set. They are grown for beauty, for pollination services, as cut flowers for arrangements (often pollen-free varieties), as cover crops, and in wildlife food plots to name just a few uses. The scientific name for sunflowers is attributed to the Greek words helios, referring to the sun, and anthos meaning flower. The sunflower is an annual plant that completes its life cycle, from germination to seed production, in one growing season. The seed produced supports various wildlife such as birds and small mammals and makes a nutritious addition to meals and snacks. The showy, small to large-sized flowers are composed of a center cluster of disc florets, that will ultimately produce the seed, surrounded by colorful ray florets that have the appearance of petals. Sunflowers produce flowers abundantly during the long hot days of summer to early fall.
Sunflowers exhibit a physiological condition known as heliotropism. Heliotropism refers to the mechanism in which flowers follow the movement of the sun, from east to west, across the sky. During the nighttime to early AM hours, the flowers will return to face an easterly direction to capture the light of the rising sun once again. As sunflowers become heavy with seed, they may exhibit less noticeable heliotropism.
Sunflowers are not difficult to grow. Seeds can be sown directly outdoors into the ground or containers, once the danger of frost has passed and soils have warmed to above 50°F. Sunflowers prefer well-draining soil with a pH between 6-7.5 for root development and growth. Locations that receive 6 to 8 hours of direct sunlight are preferable. For further assistance with growing sunflowers, see HGIC 1152 Growing Annuals. Sunflowers, especially the multi-flowered, branching type or single, large-flowered cultivars, can be heavy soil feeders. Soil that includes organic matter amendments such as composted manure is best, along with the regular application of a slow-release fertilizer. Large plants may need support as they mature to deal with strong winds or top-heaviness from seed production. Sunflowers generally have few insect pest problems and only the occasional potential bout with downy or powdery mildew.
No matter what purpose sunflowers are grown for, there are tons of cultivars available to fit the bill. Peruse seed catalogs, online seed companies, or local garden supply stores for something that suits your fancy. From mammoth single-color, single flower types to the prolific branched patterns with multiple shades of flowers, it is all out there for the growing. Be astonished by sunflowers, from the 12-footers down to the smaller 2 to 3-foot tall cultivars that fit nicely into smaller garden spaces. Above all, enjoy the elegance of sunflowers, and do not forget to visit a local sunflower festival in your area this year if possible.
The National Garden Bureau declared 2021, The Year of the Sunflower. For more information: https://ngb.org/year-of-the-sunflower/