Sunflowers can increase diversity in organic grain crop rotations, which is important for managing fertility, insects, weeds and diseases. They can also contribute to the diversification of farm revenue through access to a variety of markets.
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Fact Sheet Series 22-1
Sunflower Production
Summary
•
Sunflowers can increase diversity in grain crop rotations, which is imortant for managing fertility, insects,
weeds and diseases
•
They can contribute to the diversification of farm revenue through access to a variety of markets
•
Sunflowers are a versatile crop that is adapted to grow in a variety of soil types and climates
•
They can be incorporated into a wide range of organic rotations, including soybean, corn and wheat
WHY ADD SUNFLOWERS TO AN ORGANIC GRAIN
ROTATION?
Sunflowers are a versatile crop that is adapted to
grow in a variety of soil types and climates which can
increase diversity and add value in grain crop rotations.
A diverse crop rotation is especially important in
organic systems for managing fertility, insects, weeds
and diseases. Sunflowers can be incorporated into a
wide range of organic rotations, including soybean,
corn and wheat. With their extensive fibrous and tap
root systems, sunflowers are fairly drought tolerant and
can offer the advantage of increasing rotation length
and attracting pollinators and beneficial insects.
Sunflowers can also contribute to the diversification of
farm revenue through access to a variety of markets.
Three primary types of sunflowers are grown include
oilseed, non-oilseed (also known as confectionary), and
conoil. Oilseed sunflowers are used for vegetable oil
production and there are a few market classes based
on their oil profile including linoleic, mid-oleic (NuSun™)
and high oleic. In the US and Canada, mid-oleic is
planted on the most acreage. Oilseed sunflower can
also be processed into feed. Non-oilseed sunflowers
are grown for human food, such as snacks or nut
butter and bird food. Conoil hybrids, a cross between
oilseed and confection hybrids, are also available. They
are usually used for dehulling, but can be used for oil
or bird food as well. Sunflower marketing usually uses
cash forward contracts, but on-farm storage is also
common. Non-oilseed sunflower and specialty oilseeds
are generally contract grown.
AGRONOMIC DECISIONS FOR SUNFLOWER
PRODUCTION
Growth and Development
Sunflowers, like most crops, are sensitive to soil
conditions at planting. In northern regions of the US,
planting dates range from April 15 – July 10. Germination
can be negatively impacted by cold and wet soil,
which can be a particular concern for organic growers
with respect to damping-off diseases and weed
management. A soil temperature of 50°F to 55°F is
optimal for germination. Sunflower development
requires around 2,500 growing degree days, with
physiological maturity (R-9) reached when the back of
the head has yellowed, the bracts are turning brown
and seed moisture is around 35%. Bract color may not
be a good indicator of maturity in stay-green hybrids.
After physiological maturity, plants require time to dry
down to a moisture level that can be combined. The
industry standard for dry is 10% but starting at 15% will
reduce harvest shatter loss and can be easily air dried.
Variety Selection
Photo credit: Ben Brockmueller
Some key factors to consider for hybrid selection
are maturity, dry down, yield potential for your area,
oil percentage and disease resistance. Frost damage
before physiological maturity can decrease yield, oil
content, and test weight. In more northern regions,
selecting early to midseason varieties that dry down
quickly may be important to consider, although shorter
Fact Sheet Series 22-1
Sunflower Production
season sunflowers can have lower yields. Disease
resistance can also be considered, as traditional
breeding techniques have led to sunflower varieties
that are resistant to downy mildew, rust or Verticillium
wilt.
Soil and Fertility
Sunflowers are adapted for a range of soil types. They
do best in well-drained soils but with good waterholding capacity and a more neutral pH between 6.5
and 7.5. Due to their deep tap roots, sunflowers are able
to scavenge nutrients as deep as 3 to 4 feet.
Nitrogen is generally the most limiting nutrient for
sunflowers with recommendations dependent on
soil type and yield goals. Sunflowers tend to be less
nitrogen (N) demanding than corn, with N rates of 7590 pounds per acre typically applied before planting.
Sunflowers are also sensitive to N overapplication
with higher N rates leading to greater susceptibility to
lodging, increased susceptibility to disease and lower
oil content. Soil phosphorus (P) and potassium (K) are
recommended in the range of 30-50 pounds per acre
for P and 60-80 pounds per acre for K.
Planting Practices
Sunflower planting dates and growing conditions will
affect yield, oil content and fatty acid composition. Early
planting can lead to higher yield, reduced bird damage
due to earlier harvest date, and reduced losses from
Sclerotinia head rot. Especially in northern regions,
earlier planting can increase yields and oil percentages.
Later plantings often have lower yields, lower oil
content and may require mechanical drying if harvest is
delayed by weather.
When planting sunflowers, even spacing is important to
reduce competition between plants. Corn planters or
air seeders are recommended for planting sunflowers
while grain drills often result in skips and doubles.
Seeding Rates and Depths
Target seeding rate in organic production should be
26,000 seeds per acre for oilseed varieties, depending
on soil type and yield goals. Non-oilseed varieties
can be planted at lower seeding rates (approximately
20,000 seeds/acre). Ideal seeding depth is 1.5-2.0”
depending on seed bed conditions and soil moisture,
with row spacing ranging from 20”-36” depending on
planting and cultivation equipment. A range of seeding
densities can lead to similar yield as the plants adjust
head diameter, seed number per plant and seed size
depending on the plant population. However, head size
can affect drying rate as heads with a smaller diameter
have been found to require shorter drying time.
Weed Management
The first few weeks after planting are critical for
managing competition from weeds to maximize
sunflower yields, but after the plants are well
established, they compete well with weeds. Mechanical
cultivation with a tine weeder pre-emergence and up
to 2 weeks postemergence provides successful weed
control. Targeting blind cultivation towards weeds in
the white thread stage that have yet to emerge is the
most effective. Additional postemergence cultivation
with a row crop cultivator or spring-toothed harrow
can be performed once sunflowers reach the 4- to
6-leaf stage. Once the canopy closes, there is very little
pressure from newly emerged weeds. Mechanical
cultivation can affect the harvest population and a
higher seeding rate may be justified depending on
cultivation strategies.
Pest Management
A variety of pests can affect sunflowers including
sunflower beetle, sunflower bud moth, stem borer,
sunflower stem weevil, thistle caterpillar, sunflower
midge, red sunflower weevil, gray sunflower seed
weevil, sunflower moth, banded sunflower moth,
wireworms, cutworms, grasshoppers, pale striped
flea beetle, and lygus bug. A careful crop rotation is
an important part of an effective pest management
strategy. Planting sunflower in rotation with grasses
and other broadleaf crops is recommended with
sunflower planted once every 3 to 5 years. If there is
significant pest pressure, the rotation can be increased
to 5 to 7 years until the pressure subsides.
Disease Management
Major sunflower diseases include Sclerotinia stalk and
head rot, Verticillium wilt, rust, phoma black stem,
downy mildew and leaf spot. Disease prevalence
can be managed through carefully planned rotations
with non-susceptible crops. For example, to control
Sclerotinia, it is recommended to plant sunflowers
no more than once every 4 years in the same field
in a rotation with grasses or other non-susceptible
crops. Downy mildew can also be managed through
resistant hybrids. Controlling the microclimate at the
soil surface by adjusting row spacing and plant density
is recommended. Thirty-inch rows tend to be wide
Fact Sheet Series 22-1
Sunflower Production
enough to decrease humidity near the soil surface.
This may reduce fungal pressure while maintaining
sufficient cover to reduce weeds.
Managing Bird Damage
Bird flocks can result in serious yield losses and are
best managed with a combination of cultural practices,
habitat management, and harassment tactics. Cultural
practices include (1) keeping unplanted trails to enable
access to the fields to scare birds away (2) early weed
control to help prevent birds from being attracted to
the fields in the first place, as they will first feed on
the weeds and then the sunflowers and (3) delaying
land preparations after crops in other fields until
after sunflower harvest to provide an alternate food
source for the birds. Managing blackbird roosting sites,
especially cattail marshes, can also help reduce bird
pressure. Harassment tactics include (1) pyrotechnic
devices, which can be effective but should be used
with caution (2) electronic frightening devices, which
are not as effective due to their limited broadcast range
and (3) drones, which can be somewhat effective
especially if combined with other harassment tactics.
Frost Damage
Sunflowers seedlings are initially tolerant of frost,
but this decreases as they develop. The disk flowers
are particularly sensitive to frost with frost damage
resulting in undeveloped seed. However, frost
tolerance increases after pollination and once the
sunflowers mature, the risk of frost is minimal. For
oilseed sunflower, frost damage can result in lower
test weight and lower oil percentage. For non-oilseed
sunflower, frost can cause quality problems for both
the confectionary and birdseed markets.
Harvesting, Drying and Storage
Optimal harvest timing is important for sunflower seed
yield and quality. Physiological maturity is reached
when seed moisture is around 35%. When seed
moisture is less than 20%, sunflowers can be combined,
but 10-15% moisture is preferable. If seed moisture
is above 20%, it can result in scuffing during harvest.
However, if seeds are too dry, they can shatter in the
combine and have poor oil content. Higher yield can be
achieved by harvesting sunflowers at higher moisture
due to less field loss to bird damage and reduced
exposure to cold weather, but mechanical drying will
be required. Low-temperature bin, high-temperature
bin, batch flow, continuous flow, and natural air dryers
can be used. Sunflowers can be combined using a corn
head with roller knives or other row crop headers.
Platform headers are not recommended. Most organic
corn growers will need no additional equipment to
harvest the crop.
For storage, seed should be cleaned to remove excess
residue. It is recommended that seed moisture not be
above 10% during the winter and 8% during the summer
for oilseed sunflower and should not be above 11%
during the winter and 10% during the summer for nonoilseed sunflower. During storage, regular temperature
monitoring and adjustments are needed to reduce the
possibility of deterioration due to insects or mold.
AUTHORS
Mike Garland1, Claire Stedden2, Erin Silva3
1. Crop Development Manager, Purdue Agribusiness; 2. Outreach
specialist, Organic Grain Resource and Information Network (OGRAIN)
Program, University of Wisconsin – Madison; 3. Associate Professor,
Organic and Sustainable Cropping Systems Specialist, University of
Wisconsin – Madison
REFERENCES AND FURTHER RESOURCES
1.
2.
3.
4.
5.
Kandel, H., Endres, G., & Buetow, R. (Eds.). 2020. Sunflower
Production Guide. https://www.ag.ndsu.edu/publications/crops/
sunflower-production-guide
Darby, D.H., Halteman, P., & Harwood, H. 2019. Oilseed Production
in the Northeast. https://www.uvm.edu/extension/nwcrops/
oilseed
Agricultural Marketing Resource Center. Sunflower Profile.
https://www.agmrc.org/commodities-products/grains-oilseeds/
sunflower-profile
Tips and Tricks for Sunflower Harvest. 2020. Manitoba Crop
Alliance. https://mbcropalliance.ca/news/tips-and-tricks-forsunflower-harvest
Putnam, D.H., Oplinger, E.S., Hicks, D.R., Durgan, B.R., Noetzel,
D.M., Meronuck, R.A., Doll, J.D., & Schulte, E.E. 1990. Sunflower.
Alternative Field Crops Manual. https://hort.purdue.edu/
newcrop/afcm/sunflower.html
Factsheet 22-1. Released January, 15, 2023
The OGRAIN (Organic Grain Resource and Information Network) program provides resources and support for new, transitioning,
and experienced organic grain farmers throughout the upper Midwest. OGRAIN is housed in the Organic and Sustainable
Agriculture Research and Extension Program within the UW-Madison Department of Plant Pathology under the leadership of
associate professor Dr. Erin Silva. For more information visit our website at ograin.cals.wisc.edu. To contact us, email Erin at
emsilva@wisc.edu, or call (608) 890-1503. Learn more at https://ograin.cals.wisc.edu/.