- Sunflower pollen has medicinal, protective effects on bees
- How to Choose the Best Sunflower Varieties for Your Needs
- Cornell University
- Connect With Us!
- Sunflowers for the Insects
- Sunflowers for the Vase
- Sunflowers for the Structure
- Sunflowers for the Seeds
- Know Before You Grow
Sunflower pollen has medicinal, protective effects on bees
The study, conducted by researchers at North Carolina State University and the University of Massachusetts Amherst, showed that two different species of bees fed a diet of sunflower pollen had dramatically lower rates of infection by specific pathogens. Bumble bees on the sunflower diet also had generally better colony health than bees fed on diets of other flower pollens.
The study showed that sunflower pollen reduced infection by a particular pathogen (Crithidia bombi) in bumble bees (Bombus impatiens). Sunflower pollen also protected European honey bees (Apis mellifera) from a different pathogen (Nosema ceranae). These pathogens have been implicated in slowing bee colony growth rates and increasing bee death.
The study also showed a deleterious effect, however, as honey bees on the sunflower diet had mortality rates roughly equivalent to honey bees not fed a pollen diet and four times higher than honey bees fed buckwheat pollen. This mortality effect was not observed in bumble bees.
Jonathan Giacomini, a Ph.D. student in applied ecology at NC State and corresponding author of a paper describing the research, said that bees already seem adept at collecting sunflower pollen. Annually, some two million acres in the United States and 10 million acres in Europe are devoted to sunflowers, he said, making sunflower pollen a ready and relevant bee food.
“We’ve tried other monofloral pollens, or pollens coming from one flower, but we seem to have hit the jackpot with sunflower pollen,” said co-senior author Rebecca Irwin, a professor of applied ecology at NC State. “None of the others we’ve studied have had this consistent positive effect on bumble bee health.”
Sunflower pollen is low in protein and some amino acids, so it should not be considered as a standalone meal for bee populations, Irwin said. “But sunflower could be a good addition to a diverse wildflower population for bees,” she said, especially generalists like bumble bees and honey bees.
The NC State researchers are now planning to follow up on the study to examine whether other species of bees show the positive effects of sunflower pollen and to gauge the mechanism behind the mostly positive effects of sunflower pollen.
“We don’t know if sunflower pollen is helping the host bees fight off pathogens or if sunflower pollen does something to the pathogens,” Irwin said. Future research is aimed at figuring this out.
How to Choose the Best Sunflower Varieties for Your Needs
The ‘Sunrich’ series and ‘ProCut’ series are single-stem sunflower varieties well-suited to beginners and pros alike.
Single-stem varieties, including the Sunrich and ProCut series, are pollenless hybrids, which means they do not drop pollen on furniture, tablecloths, and clothing, as non-hybrid sunflowers do. While pollenless varieties do still produce nectar, and thus sustain nectar-feeding organisms such as butterflies and hoverflies, all bees need both nectar and pollen to survive. Pollenless sunflower varieties planted in proximity to “regular” (bisexual) sunflowers are likely to be visited and pollinated to some extent by pollinators that have visited the regular flowers. And, if left to mature on the stem rather than being cut, they will also be likely to produce some seed.
Continuing on the plus side, many single-stem sunflower varieties are really quick to bloom, needing just 60 days from seeding date to reach harvestability. In addition, there is a good selection of “day-neutral” single-stem varieties that can be grown in a hoophouse early in spring or late in fall. (See our article on how day length affect flowers for more detail.)
Single-stemmed plants are more mutable than branching types in regard to the size of the flower you choose to produce. The plants can either be crowded into a 6″ x 6″ spacing to produce smaller, bouquet-sized flowers; or they can be spaced a foot apart to produce dinner-plate sized flowers. (See our video on planning, spacing, and sequencing tips for sunflowers to learn more about how spacing influences bloom size.)
Single-stem varieties additionally have strong, thick stems and flowers of substance that make a statement and fill out a bouquet, which endears them to florists. And their vase life is amazing, particularly the pollenless ones — up to 2 weeks in plain water.
On the other hand, single-stem sunflowers produce just one flower from one seed. (A few cultivars may send up small secondary flowers in mid-summer, but this is not the norm.) This means you need to succession-plant single-stem sunflowers every 10–14 days, all season, if you want to have a continuous supply. (See our 3 sunflower succession-planting programs for guidance.) If you’re selling your blooms, you would need to charge more for single-stemmed cuts to make a good return on your investment.
10 Recommendations for Single-stem Sunflowers
‘ProCut White Nite’: Petals open with a creamy vanilla tint that turns white within a few days. Excellent choice if you are looking for a variety for weddings or to dye.
- Earliest variety: ‘ProCut Orange Excel’
- Best selection for downy mildew-resistance: ‘ProCut Orange DMR’
- Most uniform in appearance and harvest date: ‘ProCut Horizon’
- Perfect for when you want to “grow pale and interesting”: ‘ProCut White Lite’ & ‘ProCut White Nite’
- Best single-stemmed sultry redhead: ‘ProCut Red’
- Most uniform in appearance and harvest date: ‘ProCut Horizon’
- Beloved for its upfacing “lollipop” appearance: ‘Vincent’s Choice’
- Best for winter production in the South; tall and stately, with classical good looks: ‘Full Sun Improved’
- Best for the “3D look” under lower light intensity (early summer, late summer, and greenhouse conditions), drawing the eye from its creamy lemon tips into vibrant yellow petals toward a mesmerizingly dark disk: ‘Sunrich Limoncello Summer’
- Best for banner yields of delicious edible seeds: ‘Royal Hybrid 1121’
Pollen-less sunflower hybrid ‘Arbel’.
- Since sunflowers can be easily grown outside, high tunnel production of the crop only makes sense early in the season, before field production is possible.
- Early sunflowers should be transplanted from greenhouse-started seedling trays.
- Given the large size of sunflower seeds, 72- to 144-cell trays are best for seedling production.
- In moderate greenhouse temperatures (65-75 F), expect to transplant in less than 3 weeks.
- Delayed transplanting of the fast-growing seedlings will result in tall, weak plants that may have impaired growth after transplanting.
- Direct seeding in late summer for a fall crop may take advantage of frost protection afforded by the high tunnel.
The apical growing point of the lower sunflower has been removed (topped or pinched) to increase the number of flowers.
- The modern pollen-less hybrids have growth duration from sowing to harvest of between 55 to 75 days when started in early spring.
- Flower stalk and head size are directly dependent on spacing; for head diameter of 4 to 5 in., plant seedlings 6 x 6 in. in a 4-foot bed, or use a 9 x 9 in. spacing, with two seedlings per hill.
- Pinching out the plant tip after 4 leaves have expanded will double or triple flower number per plant, but these will be small, unless spacing is widened to 12 x 12 in.
- For early high tunnel planting in milder zones (Zones 6 and 7), the short daylength in mid-March will cause early flowering of some varieties such as ‘Sunrich Orange’. These plants will flower early on small stalks, and will show excessive numbers of secondary buds.
- View .pdf of sunflower variety sensitivity to day length.
‘Moulin Rouge’, a tall, late, branching sunflower variety.
- For use as cut flowers, choose varieties that do not produce pollen. These do not stain their surroundings when placed in a vase in the home.
- There is now a large range of flower colors, sizes, degree of branching, earliness available with pollen-less characteristics.
- The most common sunflower colors are orange petals surrounding a dark brown disk, but disk color can also vary to green and gold.
- Varieties that produce only a single stem usually flower over a short period of time, after which the tunnel space can be used for other crops. Branching types can be harvested for several weeks as branches come into flower.
- Sunflowers are generally harvested as cut flowers when the flower is just opening, and the ray flowers are perpendicular to the flower disk.
- The flowers should last at least a week in water at room temperature.
- There are big varietal differences in flower life after harvesting, and these relate to flower color. The standard orange types tend to be long-lived. Varieties with dark flower color, or with dark petal bases tend to shed petals in less than a week.
- Short vase life is also related to premature petal loss when flowers are roughly handled at harvest.
- Harvesting flowers during middle of the day may lead to flower wilting. These should be recut when flowers have been moved to a shaded environment.
For more information, see:
- Flower seed catalogs
- Armitage, A.M. and J.M. Laushman. 2003. Specialty Cut Flowers, 2nd Edition. Timber Press, 586 pp. Available through ASCFG
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PHOTO: Shigemi.J/Flickrby Heidi Strawn June 26, 2015
Every gardener should grow annual sunflowers—but not just for their good looks. Yes, sunflowers are cheery and gorgeous, but there are a lot of other reasons why these beauties should find a permanent a home on your farm. With a broad assortment of flower colors and forms, as well as an incredible diversity of plant heights and growth habits, sunflowers have a broad appeal. These North American natives are low-maintenance and inexpensive to grow, but knowing which varieties are best for your farm means carefully considering exactly why you want to grow them.
Sunflowers for the Insects
The bright blooms of sunflowers are a welcome mat for hundreds of different pollinators and other beneficial insects. Not only are honeybees frequent visitors, but native bee species, butterflies, beetles and other pollinating insects are, too. Vegetable crops greatly benefit from the increased diversity of pollinators encouraged by sunflowers. There are also scores of beneficial predatory insects that use the pollen and nectar of sunflowers as a food source. These good insects—including ladybugs, parasitic wasps, tachinid flies, hover flies, lacewings and many others—help control many common garden pests.
When it comes to insect-supporting sunflower varieties, be sure to avoid the pollen-less types, as they produce no protein-rich pollen for the insects. Skip the pom-pom-like double varieties, too. Their nectaries are hidden beneath a mass of petals, which insects may have a hard time accessing. Instead, here are some excellent, non-hybrid, insect-friendly sunflower varieties to add to your garden:
This heirloom sunflower bears a lot of flowers on multi-branched plants that reach 8 feet tall. Their classic-looking, yellow-petaled flowers have a dark center. Pollinators and other insects can feast on Henry Wild’s pollen and nectar for months, as the plant seems to be in continual flower throughout the growing season.
Boasting a mixture of flower colors, this old-fashioned sunflower produces 6-inch blooms on 7-foot-tall, heavily branched plants. The flowers are a mixture of yellow, gold, red, burgundy and rose-colored petals, all with dark centers. Each blossom is swarming with beneficial insects from first flower until frost.
Grown by the Arikara tribe in North Dakota, this stunning variety has been sown by generations of Native Americans and is praised for its delicious, edible seeds. Plants grow up to 10 feet and produce large, yellow-petaled flowers with dark centers. Some plants are single stalked while others are branched, but all support a broad array of insects.
Sunflowers for the Vase
If you plan to sell or use your sunflowers as cut flowers, you’ll want to look for highly branched varieties. Rather than producing one large flower, these selections produce dozens of blooms per plant. They often yield weeks of fresh-cut blossoms from a single row of plants. Because sunflowers shed a lot of pollen, pollen-less varieties make good cut flowers, as they won’t drop sticky yellow pollen all over furniture and carpets. Here are some sunflower varieties perfectly suited to the vase:
This bi-colored sunflower has a deep, dark middle and reddish-brown petals with yellow tips. It reaches 3 feet tall and produces many side branches.
This lovely variety has pom-pom-like double flowers that reach 6 inches across. Plants are 6 to 8 feet tall and have many short, flowering branches. The flowers are perky orange and look amazing in a vase.
A pollen-less, multi-branched sunflower, Cherry Rose is a bright combination of rose and yellow tones. Some flowers are more pink, while others are wine-colored, but all of them are gorgeous! Mature plants are 5 feet tall, and the flowers reach 3 inches across.
Sunflowers for the Structure
Because of their tall, straight and strong stature, some sunflower varieties make excellent living trellises. In the vegetable garden, they provide support for climbing beans, cucumbers, peas and other vining crops. You can also use them to make living “houses,” tepees and mazes for kids (and grown-ups!) to enjoy. For this purpose, it’s best to pick tall, sturdy varieties.
This gigantic sunflower makes an excellent living trellis for pole beans and winter squash. Planted in groups, they can form a miniature forest or tepee. Reaching a whopping 16 feet tall and producing a single gargantuan flower, American Giant is one spectacular sunflower.
Mammoth Gray Stripe
Grown by many farmers for its delicious seeds, this super-tall selection is also a great structural plant. The seeds are black-and-white striped and have a high oil content. The mature plants top out at 12 feet tall—perfect for making a sunflower maze!
The perfect choice for dense plantings, Holiday forms many thick, sturdy branches on a 5- to 7-foot-tall plant. The flowers are a beautiful orange-yellow, and when planted in a close row, the branches overlap, forming a living wall or fence, perfect for screening neighbors or creating a border around the vegetable garden.
Sunflowers for the Seeds
If you enjoy growing sunflowers for their edible seeds, be sure to grow varieties bred for excellent seed production. Whether you plan to eat the seeds yourself or use them as birdseed, these selections boast massive blooms, filled to the brim with meaty seeds.
If you want to grow seeds for human consumption or for birdseed, this is the variety for you! The seeds are plump and tasty. Reaching 5 to 7 feet tall, the flowers reach nearly a foot across and produce hundreds of seeds.
Among the largest seeded sunflowers in existence, Mongolian Giant produces seeds that are over 1 inch long! Single-flowered plants grow up to 18 feet tall, and yellow flower heads are each 1½ feet wide.
With flowers that are a mind-blowing 2 feet across, Titan produces scores of delicious, large seeds. Plants reach 10 to 12 feet tall and bear classic yellow-petaled flowers. The stems are extremely sturdy.
Know Before You Grow
No matter which sunflowers you decide to grow, sow their seeds outdoors, directly into the garden, after the danger of frost has passed and when the soil temperature reaches about 60 degrees F. Plant seeds 1/2 inch deep and 1 foot apart. Sunflower seeds germinate in 10 to 14 days at optimum soil temperatures. For row plantings, be sure to separate the rows by at least 2 to 3 feet to ensure plenty of air circulation and room for harvesting. Sunflowers grow best in—you guessed it—full sun.