Sunflower ~ Helianthus annuus Plant Care Guide
The sunflower (Helianthus annuus) is an annual plant native to the Americas. It possesses a large inflorescence (flowering head), and its name is derived from the flower’s shape and image, which is often used to depict the sun. The plant has a rough, hairy stem, broad, coarsely toothed, rough leaves and circular heads of flowers. The heads consist of many individual flowers which mature into seeds, often in the hundreds, on a receptacle base. From the Americas, sunflower seeds were brought to Europe in the 16th century, where, along with sunflower oil, they became a widespread cooking ingredient. Leaves of the sunflower can be used as cattle feed, while the stems contain a fibre which may be used in paper production.
Botanical name: Helianthus
Plant type: Flower
Sun exposure: Full Sun
Flower color: Yellow
Bloom time: Summer
Sunflowers say “summer” like no other plant.
Sunflowers are annuals with showy, daisylike flowerheads that are usually 2-4 inches across and bright yellow (though occasionally red). Tall and course, the plants have creeping or tuberous roots and large, bristly leaves. Today, varieties have even been developed for small spaces and containers.
Most sunflowers are remarkably tough and easy to grow as long as the soil is not waterlogged. Most are heat- and drought-tolerant. They make excellent cut flowers and many are attractive to bees and birds.
- Sunflowers grow best in locations with full sun; they prefer long, hot summers to flower well.
- Though they’re not too fussy, sunflowers thrive in slightly acidic to somewhat alkaline (pH 6.0 to 7.5).
- If possible, put seeds in a spot that is sheltered from strong winds, perhaps along a fence or near a building.
Planting Sunflower Seeds
- It’s easiest to sow seeds directly into the soil after the danger of spring frost is past. Ideally, the soil temperature has reached 55 to 60 degrees F.
- Plant the large seeds no more than 1 inch deep and 4 to 6 inches apart in well-dug, loose soil after it has thoroughly warmed, from mid-April to late May.
- A light application of fertilizer mixed in at planting time will encourage strong root growth to protect them from blowing over in the wind.
- Experiment with plantings staggered over 5 to 6 weeks to keep enjoying continuous blooms.
- Give plants plenty of room, especially for low-growing varieties that will branch out. Make rows about 30 inches apart. (For very small varieties, plant closer together.)
- When the plants are six inches high, thin them to two feet.
- If you see birds scratching around for the seeds, spread netting over the planted area until seeds germinate.
- Water plants deeply but infrequently to encourage deep rooting.
- Feed plants only sparingly; overfertilization can cause stems to break in the fall.
- Tall species and cultivars require support. Bamboo stakes are a good choice for any plant that has a strong, single stem and needs support for a short period of time.
- Birds and squirrels will show interest in the seeds. if you plan to use the seeds, deter critters with barrier devices. As seed heads mature and flowers droop, you can cover each one with white polyspun garden fleece.
- If you have deer, keep them at bay with a tall wire barrier.
- Sunflowers are relatively insect-free. A small gray moth sometimes lays its eggs in the blossoms. Pick the worms from the plants; if you have an infestation, spray with Bt.
- Downy mildew, rust, and powdery mildew can also affect the plants. If fungal diseases are spotted early, spray with a general garden fungicide.
- To harvest seeds, keep an eye out for ripeness. They’re ready when the bracts begin to dry. Hang the heads upside down until they’re thoroughly dry in a place that’s safe from birds and mice.
- For indoor bouquets, cut the main stem before its flower bud has a chance to open to encourage side blooms. Cut stems early in the morning, when the buds first start showing color and are just beginning to open.
- Arrange sunflowers in tall containers that provide good support for their heavy heads, and change the water every day to keep them fresh.
Everyone is familiar with the huge sunflowers that grow on towering eight-foot-tall stalks. But, did you know that some varieties top off at a modest 15 inches?
- The towering ‘Mammoth’ variety is the traditional giant sunflower. It is excellent for snacks and bird feeds, too.
- ‘Autumn Beauty’: One of the most spectacular cultivars, has many 6-inch flowers in shades of yellow, bronze, and mahogany on branching stems up to 7 feet tall.
- ‘Sunbeam’: A standout bouquet flower, the van Gogh sunflower grows on a 5-foot plant with 5-inch flowers. The big, no-mess, pollenless flowers have rich, golden-yellow rays.
- ‘Teddy Bear’: Just 2 to 3 feet tall, this small flower is perfect for small gardens and containers. The fluffy, deep-gold, 5-inch blossoms last for days in a vase.
- Attracts Butterflies
- Attracts Birds
- Some varieties provide small black seeds that are used in cooking oil, margarine, cosmetics, and animal feed; they are the best sunflower seeds for attracting the greatest variety of songbirds.
- The bigger, striped seeds are grown for snacking and as an ingredient in bread and health foods. They, too, are used for feeding birds, especially larger species such as jays and mourning doves.
- For eating, the seeds must be dried on the plants. Rub the seeds off and soak them overnight in a gallon of water to which a cup of salt has been added, then dry them again in an oven at 250 degrees F for 4 to 5 hours. Store them in an airtight container.
- One way to remove them is to rub the head of the sunflower across an old washboard or something similar. Just grip the head and rub it across the board as if you were washing clothes.
Wit & Wisdom
- Need a bird seeder? Save dry heads and set them out in winter.
- Save thick sunflower stems and dry them for winter kindling.
- Interesting Fact: An anonymous buyer paid over $39 million in 1987 for Vincent van Gogh’s Sunflowers.
- Kansas is “The Sunflower State.”
Here and yonder, high and low,
Goldenrod and sunflowers glow.
–Robert Kelley Weeks (1840–76)
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