Helianthus annuus, also known as common sunflower, originates from North America and is a part of a genus with around 70 species. The tall yellow bloomer is from the Asteraceae plant family.
It is known for its amazing ability to turn itself towards the sun and has plentiful seeds that can be used for a multitude of products.
The growing conditions for sunflowers are easy to accommodate. It involves knowing the best soil types, watering schedules, temperature preferences, and more.
If you are thinking about growing sunflowers, find out everything you need to know about their care below!
The best soil for growing sunflowers is well-draining with a slightly acidic pH of 6.0 to 6.8. They tolerate clay loam and sandy loam soils well.
Sunflower plants should receive water every 14 days to maximize their yields. You can opt to wait for rainfall, use irrigation, or deeply water using a hose or watering can.
As you may be able to tell by its name, sunflowers enjoy full sun exposure. They enjoy it so much, they purposely seek it out by turning themselves towards where the sun is shining.
Humidity & Temperature
When planting, the temperature should roughly be 46°F to 50°F or 7.78°C to 10°C. When growing, they flourish in ambient temperatures between 70°F and 78°F or 21.1°C and 25.56°C. The plant can withstand fairly humid conditions, but you must always ensure your soil is draining well when humidity is high.
Sunflowers are hungry plants that require a fair amount of nutrient replenishment. They respond well to nitrogen, phosphorus, and potassium.
Commercial sunflower growers apply nitrogen-based fertilizers based on expected crop yields and depending on soil conditions and location.
The average sunflower grower will benefit from using 10-10-10 or 5-10-10 NPK ratio fertilizer. You can opt to apply fertilizer directly after new growth emerges or two weeks out from your last frost date.
Diseases & Pests
Although pests are not a frequent problem for Helianthus annuus, aphids, stink bugs, and caterpillars can affect them occasionally. Although, if you find any of these insects on your plant, use insecticides with caution. They have the potential to harm valuable pollinators.
Fungi-based diseases can occur in Helianthus plants, and typically occur from irrigation and poor soil drainage. Proper soil and watering practices can help prevent common fungi diseases found in sunflowers.
If you frequently deadhead sunflowers, it can encourage healthier and fuller growth. It is also a great practice if you don’t want the plant to drop seeds and self-sow. To deadhead a sunflower, you cut 4″ down the stem from the flower head.
Deadheading your flowers when they are starting to wilt will also allow you to harvest seeds. To do so, place the cut flower into a breathable dry bag upside down.
Helianthus annuus typically blooms in the later months of summer to the early fall season. That is after 90 to 100 days of initial planting.
Sunflower Meaning and Symbolism
The beautiful thing about sunflowers, aside from their appearance, is the deep meaning and symbolism they hold.
Let’s start with how the plant got its genus name, Helianthus. Firstly, the genus name is a combination of two Greek words, which are helios and anthos. The former means sun, and the latter means flower. The name sunflower came to be because of the plant’s ability to face itself towards where the sun is shining.
Additionally, the Greek myth of Apollo and Clytie gives a fantastical explanation as to why the flowers do that. Because of this story, many consider sunflowers to symbolize loyalty and adoration.
Despite the story of Apollo and Clytie, sunflowers represent many things across different cultures.
To Native Americans or Indigenous people, sunflowers represent bounty, harvest, and provision because of its ability to provide valuable byproducts, such as seeds and pigment.
But in Chinese culture, sunflowers are signs of good fortune and vitality.
Because of the flowers’ traditionally yellow coloring, they also represent friendship and are flowers best given to those you have platonic love for. But, there is a slight caveat. Because of their symbolism of adoration, loyalty, and strength from Greek mythology, sunflowers can also be given as third wedding anniversary presents.
Helianthus Life Cycle
There are four development stages within a Helianthus plant’s lifespan. Those are the vegetative stage, reproduction, blooming, and senescence or dieback. These stages happen from the point of planting to harvest.
The vegetative stage or vegetative emergence occurs one to two months after planting and seed germination. In this stage, the plant will be a seedling that has broken through the soil for around 13 days. And once it has grown a leaf that is 4cm long, it has entered and completed part one of the vegetative stage. Part two of the vegetative stage occurs once a second leaf that is 4cm long emerges.
The reproduction phase occurs once a bud forms between the leaf clusters. And once this phase ends, you will see a bright yellow bloom. It can take 30 days for the plant to bloom.
The blooming stage comes at the end of reproduction. It stays in its bright blooming glory for 20 days and allows pollinators to do their job. If you wish to use the flowers for decor, this is the time to do so.
Senescence or Dieback
Senescence or dieback is when it is time to harvest sunflower seeds. Once the plant has turned brown and droops, remove the flowerhead 4″ down from the stem. Then place the flowerhead downwards in a breathable but dry bag. You can expect your sunflower seeds to be ready for harvest around 110 to 125 days from planting the flower.
Types of Sunflowers (Helianthus)
Despite the common sunflower being the most familiar form of sunflower planted all over the United States, Helianthus is a species of around 70 flowering plants and consists of annuals and perennials that come in various sizes, shapes, and colors.
Dwarf sunflower varieties
Dwarf sunflower varieties are cultivators of the plant that are 3′ tall or less. Below are a few cultivators of the dwarf variety.
- Teddy Bear
The teddy bear cultivator can grow between 24″ to 36″ and 12″ to 24″ wide and it has double petals that have a unique soft and fluffy appearance.
- Double Dandy
The double dandy cultivator can grow between 12″ to 24″ tall and 18″ wide and it has burgundy to deep purple blooms and cream-colored tips.
The elf cultivator of sunflowers is one of the smallest of the dwarf variety; they grow between 14″ to 16″ tall and 4″ to 6″ wide. Aside from their height, they have the appearance of a common sunflower.
- Little Becka
The little becka cultivator grows between 24″ to 36″ tall and 5″ wide, and they have stunning burnt orange to red petals with yellow tips.
- Ms. Mars
The Ms. Mars cultivator of sunflowers grows to 23″ tall and 6″ wide, and its petals are purple with an ombre effect.
Multi-headed sunflower varieties
Multi-headed sunflowers, also known as branching sunflowers, are cultivators that grow more than one flower per stalk. Below are a few varieties of multi-headed sunflowers.
- ‘Shock ‘O Lat’
The shock ‘o lat cultivator of sunflowers is a branching variety with dark brown to red coloring with yellow tips and they can grow to 6’ tall and 6″ wide.
- Wild Sunflower
The wild cultivator of sunflowers can grow 20 flowers or more per stalk. They also grow between 2′ to 8′ tall and 3″ to 4″ wide. This variety has the standard bright yellow petals.
The joker cultivator of sunflowers can grow multiple flower heads and becomes 6′ tall and 6″ to 7″ wide, and it has dark brown to bright red petals that turn to yellow at the ends.
The sonja cultivator is also a branching variety and can grow to a mere 3′ tall and 3″ or wider. They have wide centers with bright yellow petals.
- Lemon Queen
Lemon queen sunflowers are a variety that branches and have the standard bright yellow coloring, and they can reach 5′ to 9′ tall and 4″ to 6″ wide.
Tall sunflower varieties
Tall sunflowers, also known as giant cultivators, are sunflower types that can grow to 8′ or more in height.
The cyclops cultivator reaches 15′ tall and has the typical yellow coloring.
- American Giant
The American giant cultivator can become 14′ tall and 10″ wide, and it has the standard bright yellow coloring.
- Candy Mountain
The candy mountain cultivator is 8′ to 10′ tall and has red centers with yellow petal tips.
- Mammoth Russian
The mammoth Russian cultivator can reach 12′ tall and 4″ to 6″ wide, and it has the common bright yellow coloring.
The giganteus cultivator of sunflowers reaches 10′ in height and 1′ wide, and it has the familiar yellow coloring.
Commercial sunflower varieties
There are typically three varieties of sunflowers grown commercially. They all have different uses. Below is a bit of information about each type.
Oilseed sunflowers are grown for vegetable oil production.
Nonoilseed sunflowers are grown for human and bird food products.
Conoil sunflower plants are primarily for dehull confection and bird foods.
How to Grow Sunflowers for Beginners
Are you new to growing sunflowers? If so, you will be happy to know that they are great to plant for beginners because of their pest-resistant nature, heat tolerance, and astounding growth rate.
Where to Plant
Sunflower seeds can be planted in pots and started indoors or directly into outdoor soil. If planting sunflower seeds outdoors, wait two weeks from your last frost date and ensure that the soil is around 50°F or 10°C and has a pH of 6.0-6.8. The planting location you choose should receive full sun for six to eight hours daily.
How to Plant
It’s important to provide your flowers with enough room to grow if starting them in a container indoors, space the seeds 4″ to 5″ apart. You can transplant them into the ground once the seedlings reach a few inches tall. When planting the seeds directly into the ground or transplanting seedlings from pots, ensure that each seedling has at least 8″ in diameter of individual space. Whether you are starting the plant indoors or directly planting into the ground, the soil must be well draining, and it is best to apply 5-10-10 or 10-10-10 NPK fertilizer.
Growing Sunflowers in Pots
Sunflowers can thrive in pots as they do in the ground; you simply need to choose the right size pot for the variety of sunflowers.
If you wish to grow from seeds, ensure to place seeds 4″ to 5″ apart in a well-draining but moist soil mixture. Once the seedlings reach a few inches tall, it is time to transplant them into bigger containers. There should only be one flower per 8″ container. The container should also be 12″ to 18″ to accommodate the roots.
After that is all said and done, you can follow the typical watering schedule, lighting requirements, and fertilization recommendations.
How to Harvest Sunflowers
Harvesting sunflowers is a rewarding experience. The tall blooming plant can be used for a variety of purposes.
If you wish to use them for centerpieces or decoration, harvest the flowers when they are in their blooming phase, that is when they look their best.
If you want to use the flower for its seeds, you have to wait until the dieback stage. Once you notice the flower browning and drooping, you can remove the deadhead from the stem by cutting 4″ below the flowerhead. Then you will want to place the flower head in a dry but breathable bag upside down. That will allow the seeds to freely drop from the flowerhead and contain them.
Benefits of Sunflowers and Their Seeds
Sunflowers are a commercial crop coveted for their many uses. There are even some health benefits associated with the consumption or use of its seeds and oil.
According to research, sunflowers may have a role in combating bacterial and fungal infections, cardiovascular diseases, skin diseases, chronic inflammatory conditions, and cancers . That is potentially due to compounds, vitamins, and minerals in the plant’s seeds.
The seeds are also used in many commercially sold bird foods.
Sunflower oil has linoleic acid, which helps skin moisture retention. It is a fantastic addition to any winter body skincare routine.
Sunflower oil is also great for making baked goods. It works as a substitute for vegetable oil thanks to its similar flavor profile, consistency, and smoke point.
Sunflower Companion Plants
Sunflowers grow well with a wide variety of plants. Some plants benefit from the shade sunflowers provide, including daisies, snapdragons, cucumbers, squash, lettuce, basil, and kale. Zucchini and cucumbers also benefit from being grown with tall Helianthus plants because they can use the flower’s sturdy stalks to vine upwards. Others benefit from the plant’s ability to attract pollinators or move aphids away from them, including tomatoes, red peppers, and zucchini.
There are also several plants out there that function as great companions to protect the sunflowers. Below you will find the top beneficial plants to grow with sunflowers.
Crimson clover helps crowd out weeds that compete with budding sunflower plants, drive nitrogen down into the soil, and attracts pest predator insects.
The tall stalks and deep roots of corn and sunflowers help each other obtain and maximize the nutrients and water they need.
Garlic and Onion
Garlic and onion both have the ability to drive away pests, thanks to their pungent smell.
The large leaves of pumpkin help keep weeds under control, so the sunflower does not have to compete.
The large vines and leaves help crowd out weeds for young sunflower plants. Sunflowers in turn, increase attraction to the melons from pollinators.
The smell of chives helps keep aphids as well as other pests away.
Sunflower vs Jerusalem artichoke
Jerusalem artichoke is in fact a species of sunflower with its scientific name being Helianthus tuberosus. It differs from common sunflowers because of its underground tubers that have a similar appearance to ginger. Jerusalem artichokes and common sunflowers can reach 10′ in height and have bright yellow flowers. Although, common sunflower heads are bigger than that of Jerusalem artichokes.
Frequently Asked Questions
Whether or not your sunflowers will return in the coming years depends on their variety. For example, firecrackers, teddy bears, and mammoth sunflowers are annuals, meaning they only last a season. And Lemon queen, Jerusalem artichoke, and the western cultivator are perennials, meaning they will come back year after year for three years or more. Despite some varieties of sunflowers being annuals, they may reappear from dropping seeds and self-sowing.
Like many aspects of sunflowers, the variety will determine how tall the plant becomes. Some cultivators can reach 14′ tall. The most common species, Helianthus annuus, reaches 10′ in height.
Sunflowers are considered relatively easy to grow thanks to their heat tolerance, fast growth rate, and pest resistance. Additionally, the plant originates from North America and can adapt to most weather conditions in the continent.
Common sunflowers can produce 1000 to 2000 seeds. These seeds are then used for bird food, oil, and so much more.
Nandha, R., Singh, H., Garg, K., & Rani, S. (2014, March 11). Therapeutic Potential of Sunflower Seeds: An Overview. ResearchGate. Retrieved November 11, 2022, from https://www.researchgate.net/profile/Ruchika-Nandha/publication/275653985_THERAPEUTIC_POTENTIAL_OF_SUNFLOWER_SEEDS_AN_OVERVIEW/links/554342900cf24107d394983a/THERAPEUTIC-POTENTIAL-OF-SUNFLOWER-SEEDS-AN-OVERVIEW.pdf