Sunflowers

5 Things about Sunflowers

Botanical Information

The sunflower's botanical name is Helianthus annuus. The genus Helianthus consists of about 150 different species, mostly from Central and North America. This genus belongs to the daisy or Asteraceae family. Helianthus is derived from the Greek words helios and anthos, meaning “sun flower,” because of its round head with the outside ray flowers that together look like the radiant sun. The species name annuus means “annual.” The round head is made up of many tiny flowers (disk flowers), which is why when the flower head is mature, it contains many seeds. Sunflowers are the only North American species to become a major agronomic crop. The US Forest Service indicates that while the sunflower is found across the United States, its native range is probably the central and southern US and Mexico.

They are available in many different sizes and colors

Sunflowers come in various sizes and colors. Depending on the type, they can range from 2 to 10 feet in height and have yellow, pale white, orange, red, or purple flowers. The Mammoth Russian or Russian Giant sunflower was developed by the Russians and introduced to the United States in 1893.

There are different categories of sunflower varieties. Branching cultivars produce multiple blooms on the same plant over a long period. Examples of branching cultivars are 'Sonja', 'Soraya', and 'Teddy Bear'. Pollenless cultivars are ideal for cut flowers as they do not shed pollen when used in arrangements. Examples of pollenless cultivars are 'Buttercream' (branching) and 'Double Quick Orange' (single-stem, double flower). Dwarf varieties are typically shorter than three feet, with examples like 'Teddy Bear' and 'Sunspot'. Semi-dwarf varieties range in height from three to eight feet, including 'Cappuccino' and 'Chianti'. Lastly, there are giant or tall cultivars that grow taller than eight feet, such as the 'Mammoth Russian' which can grow up to 12 feet tall.

Urban Soils and Heavy Metals

Did you know that sunflowers can help remove heavy metals from soils? If you live in an urban area, you might be worried about heavy metal contamination in your soils. Sunflowers use a natural process called phytoremediation to remove heavy metals from the soil. They are considered hyper-accumulators, meaning they can take up large amounts of heavy metals. However, it's important to note that the seeds produced by these sunflowers should not be consumed as they may contain heavy metals. At the end of the growing season, it's best to bag the plant debris and dispose of it in the trash, rather than composting it, to avoid reintroducing heavy metals back into the garden. If you want to test your soil for heavy metal contamination, you can reach out to other state extension labs as the Virginia Tech Soil Testing Lab does not provide testing for heavy metals. Michigan State University Extension provides a list of other state extension labs that offer heavy metals testing.

Succession Planting for Season Long Flowers

Sunflowers are easy to grow from seed. You can plant them directly into the soil after it has warmed up in the spring. Since birds and small rodents like to eat the seeds, many home gardeners start the seeds indoors to protect them from being eaten and then transplant them outside once they have started growing and have developed the first set of true leaves. Sunflowers thrive in full sun, and their flower heads follow the sun throughout the day, a behavior known as heliotropism. The size of the plants varies depending on the cultivar, so it's best to follow the spacing recommendations on the seed packet. For continuous flowering throughout the season, consider planting multiple varieties of sunflowers with different maturation times or make multiple plantings of the same variety at intervals of 1-2 weeks. Sunflowers usually go from seed to bloom in 50-80 days, depending on the variety, which means there's still time to plant them for beautiful fall blooms!

Enjoy Sunflower Festivals! 

Enjoy sunflower festivals! These are wonderful agritourism events found around the state from summer to fall. Acres of sunflowers make a beautiful backdrop for pictures, and you can get bouquets to take home. Some even have sunflower mazes for you to wander through.