Fertilizing sunflower in Minnesota (2023)

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  5. Sunflower fertilizer guidelines

Quick facts

  • Sunflower is highly responsive to nitrogen (N).
  • Nitrogen rates should be adjusted for the type of sunflower grown.
  • Suggested nitrogen fertilizer rates are no longer based on yield goals minus N fertilizer credits, as recent data has not shown a link between the yield of sunflower and N fertilizer requirements.

Recommended N fertilizer rates

Recommended rates of nitrogen (N) should be based on the value of the sunflower seed in price per harvested pound and the unit price per pound of N applied.

The suggested rate of N also varies based on the type of sunflower grown.

  • Nitrogen suggestions for oilseed sunflower are given in Table SF-1.
  • Suggestions for confection sunflower production are given in Table SF-2.
  • Guidelines are based on suggestions for sunflower grown under conventional tillage for Eastern North Dakota, which has similar climate and soils as Northwest Minnesota.
  • Suggested first and second year N credits are listed in Tables SF-3 and SF-4.

The N rates suggested in Tables SF-1 and SF-2 include all known sources of N including the amount of Nitrate-N in a two-foot soil sample and any N credits from previous crops. We suggest sampling for Nitrate-N. Samples can be collected in the fall after the previous crop has been harvested.

For more specific recommendations, North Dakota State University has an interactive sunflower N calculator.

Nitrogen application rate tables


Table SF-1. Total known available N (lb./acre) for oilseed sunflower in situations based on N cost and sunflower harvest price. Total known available N includes soil test N to 2 feet, previous crop credit and fertilizer amendment N rate.

* Chart adapted from NDSU Extension Publication SF713.

(Video) How to Grow Sunflowers Successfully At Home 🌻

Sunflower seed price per pound harvested N use @$.20/lb N use @$.30/lb N use @$.40/lb N use @$.50/lb N use @$.60/lb N use @$.70/lb N use @$.80/lb N use @$.90/lb N use @$1/lb
$0.09/lb 150 lb 135 lb 124 lb 111 lb 96 lb 84 lb 72 lb 59 lb 47 lb
$0.12 150 145 135 125 116 106 96 87 78
$0.15 150 150 143 135 127 119 112 104 96
$0.18 150 150 148 141 135 128 126 115 109
$0.21 150 150 150 146 141 135 129 124 118
$0.24 150 150 150 150 145 140 135 130 125
$0.27 150 150 150 150 148 144 139 135 131
$0.30 150 150 150 150 150 147 143 139 135
$0.33 150 150 150 150 150 150 150 150 138
$0.36 150 150 150 150 150 150 150 150 142
$0.39 150 150 150 150 150 150 150 150 144
$0.42 150 150 150 150 150 150 150 150 146
$0.45 150 150 150 150 150 150 150 150 148
$0.48 150 150 150 150 150 150 150 150 150
$0.51 150 150 150 150 150 150 150 150 150
$0.55 150 150 150 150 150 150 150 150 150
$0.60 150 150 150 150 150 150 150 150 150

Table SF-2. Total known available N (lb./acre) for confection sunflower in situations based on N cost and sunflower harvest price. Total known available N includes soil test N to 2 feet, previous crop credit and fertilizer amendment N rate.

*Chart adapted from NDSU Extension Publication SF713.

Sunflower seed price per pound harvested N use @$.20/lb N use @$.30/lb N use @$.40/lb N use @$.50/lb N use @$.60/lb N use @$.70/lb N use @$.80/lb N use @$.90/lb N use @$1/lb
$0.09/lb 160 lb 107 lb 43 lb 0 lb 0 lb 0 lb 0 lb 0 lb 0 lb
$0.12 160 155 107 59 11 0 0 0 0
$0.15 160 160 145 107 69 30 0 0 0
$0.18 160 160 160 139 107 75 43 11 0
$0.21 160 160 160 160 134 107 79 52 25
$0.24 160 160 160 160 155 131 107 83 59
$0.27 160 160 160 160 160 149 128 107 86
$0.30 160 160 160 160 160 160 145 126 107
$0.33 160 160 160 160 160 160 160 142 139
$0.36 160 160 160 160 160 160 160 155 151
$0.39 160 160 160 160 160 160 160 160 160
$0.42 160 160 160 160 160 160 160 160 160
$0.45 160 160 160 160 160 160 160 160 160
$0.48 160 160 160 160 160 160 160 160 160
$0.51 160 160 160 160 160 160 160 160 160
$0.55 160 160 160 160 160 160 160 160 160
$0.60 160 160 160 160 160 160 160 160 160

Table SF-3. Suggested nitrogen credits for various crops that might precede sunflower in a crop rotation. Use these credits when the soil nitrate test is used.

*For harvested alfalfa, if the third or fourth cutting was not harvested, add 20 pounds N per acre to the N credits listed.

(Video) Sunflower Growing Tips
Previous crop 1st year N credit lb. N/acre
Soybean 20
Edible beans, field peas 10
Harvested sweet clover 10
Harvested alfalfa* or non-harvested sweet clover
4-5 plants/ft2 75
2-3 plants/ft2 50
1-2 plants/ft2 25
1 or fewer plants/ft2 0
Harvested red clover 35
Yellow leaves at harvest 0
Light-green leaves at harvest 15-30
Dark-green leaves at harvest 60-80

Table SF-4. Suggested nitrogen credits when sunflower is grown 2 years after a legume crop.

Previous legume crop 2nd year N credit lb. N/acre
Alfalfa (4+ plants/ft2) 35
Non-harvested sweet clover 35
Alfalfa (2-3 plants/ft2) 25
Birdsfoot trefoil 25
Red clover 20

Phosphate, potash and other nutrients


Table SF-5. Phosphate fertilizer guidelines (pounds of P2O5 suggested to apply per acre) for sunflower production based on either the Bray-P1 or Olsen soil methods test reported in parts per million (ppm).

Use one of the following equations if you want a phosphate guideline for a specific soil test and a specific expected yield:

  • P2O5 rec = [0.0225 - (0.0011) (Bray P in ppm)] (Expected yield)
  • P2O5 rec = [0.0225 - (0.0014) (Olsen P in ppm)] (Expected yield)
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Expected Yield Bray-P1
Expected Yield Olsen
0-5 ppm
0-3 ppm
6-10 ppm
4-7 ppm
11-15 ppm
8-11 ppm
16-20 ppm
12-15 ppm
21+ ppm
16+ ppm
1400-1900 lb./acre 55 lb./acre 35 lb./acre 15 lb./acre 0 lb./acre 0 lb./acre
1901-2400 lb./acre 65 45 20 0 0
2401-2900 lb./acre 75 55 25 0 0
2901-3300 lb./acre 85 65 25 10 0
3300+ lb./acre 90 70 30 10 0

Table SF-6. Potash fertilizer guidelines (pounds of K2O suggested to apply per acre) for sunflower production based on the ammonium acetate potassium test reported in parts per million (ppm).

Use the following equation if you want a potash guideline for a specific soil test and a specific expected yield:

  • K2O rec = [0.0410 - (0.00027) (Soil test K in ppm)] (Expected yield)

CAUTION: Do not apply more than 10 pounds N + K2O per acre in contact with the seed for medium to fine textured soils. Starter fertilizer placed on the seed is not suggested for sandy textured soils.

Expected Yield 0-40 ppm 41-80 ppm 81-120 ppm 121-160 ppm 161+ ppm
1400-1900 lb./acre 55 lb./acre 40 lb./acre 20 lb./acre 10 lb./acre 0 lb./acre
1901-2400 lb./acre 75 50 30 15 0
2401-2900 lb./acre 90 65 35 20 0
2901-3300 lb./acre 110 75 40 25 0
3301+ lb./acre 115 80 45 25 0

Research trials conducted in Minnesota have shown that most secondary macronutrients and micronutrients are not needed in a fertilizer program for sunflower production.

The need for sulfur (S) for sunflower has not been evaluated in Minnesota. The likelihood of sulfur deficiency on soils high in clay content (loam soils or heavier) is low if soil organic matter content is 2-3% or greater in the top six inches. The likelihood of an S deficiency is greater for sandy textured soils low in organic matter. If a sulfur deficiency is anticipated, an application of 10 pounds of S in the sulfate form at or before planting or post emergence before the R1 growth stage may be required. We suggest you apply a sulfate or thiosulfate form.

Do not place ammonium thiosulfate (12-0-0-26) in direct contact with the seed. Do not place fertilizers containing boron in direct contact with the seed.

(Video) How sunflowers🌻 #Crossing with Pollen grains... Making Hybrid seeds #Fertilization Part-2

Authors: Daniel E. Kaiser, Extension nutrient management specialist, and Keith Piotrowski, director of the University of Minnesota soil testing laboratory

Reviewed in 2023

Page survey

(Video) Nuseed U.S. & Canada - Collecting Sunflower Pollen in Breckenridge, MN


What rate of fertilizer do sunflowers need? ›

Some N may be applied in combination with starter fertilizers, but the rate should be less than 10 pounds of N per acre. Most efficient use can be obtained by applying N just ahead of planting. However, apply all of the fertilizer before heading (bud stage) to maximize yields and N use efficiency.

Is fertilizer recommended for sunflowers? ›

You should fertilize sunflowers to keep the plants healthy and blooming. These plants are heavy feeders, and newly planted sunflowers acclimate more quickly and have a fast growth rate when they are fertilized. It's a good idea to fertilize annual and perennial sunflowers to help the plants reach their full potential.

What is the best way to fertilize sunflowers? ›

Perennial sunflower varieties, such as Helianthus maximiliani, benefit from annual fertilization. Apply a low-nitrogen fertilizer 6 inches away from the plant stems in early summer when new growth begins. Water after fertilizing, so the nutrients can seep into the soil.

Is Miracle Gro good for sunflowers? ›

While sunflowers are not big feeders, you will get more and better blooms if you make sure they get a steady stream of nutrition. A month after planting, begin feeding sunflowers with Miracle-Gro® Water Soluble All Purpose Plant Food.

Do sunflowers need a lot of nitrogen? ›

One of the most important nutrients for sunflowers is nitrogen. Sunflowers cannot survive without nitrogen, but too much can be a problem. Too much nitrogen can actually decrease the oil concentration in seeds, which decreases the quality of the crop.

How often do you apply 12 12 12 fertilizer? ›

Ideal for vegetable and flower gardens, shrubs and landscape plantings. The quick release formula can be applied every 30 days through-out the growing season to provide primary nutrients to promote plant growth. Parts made in the U.S.A.

How much fertilizer do I need for sunflowers per acre? ›

Recent South Dakota fertilizer-N response studies found an economically optimal fertilizer-N rate of approximately 80 lbs N/ac was very common regardless of sunflower yield. It is important to note that sunflowers are sensitive to over application of N.

Do sunflowers like a lot of water? ›

Although sunflowers require a lot of water to germinate, they only require an inch of water per week during the growing season. Use a watering nozzle to easily water once a week until the top 6 inches of soil is moist.

How do I make my sunflowers bloom more? ›

Keep them deadheaded until the end of the season. If you deadhead your sunflowers, they will keep pumping out new blossoms in their will to create seeds and more sunflowers. Don't cut the stalk way back, the next sunflower often forms just inches from the place you deadheaded.

Can sunflowers grow without fertilizer? ›

In fact, sunflowers are known to be extremely heavy feeders throughout the growing season. While it is possible to grow them without feeding sunflower plants, nitrogen, phosphorus, potassium, and a wide range of micronutrients will all need to be present in the soil in order to obtain the best results.

What do sunflowers need the most? ›

To grow well, they need plenty of sunlight (approximately 6-8 hours a day) so it's important to plant them in a spot that gets plenty of sunlight throughout the day. Sunflowers also need plenty of space as they have long roots that need to stretch out so plant them in an area with well-dug, loose, well-draining soil.

Do coffee grounds help sunflowers grow better? ›

Increases Soil Acidity

Coffee grounds aren't good for every plant as they raise the acidity level of the soil, but for acid-loving plants such as sunflowers, they are perfect. What is this? Not only do coffee grounds increase the amount of organic content in the soil, but they also make it perfect for sunflowers.

Is Epsom salt good for sunflowers? ›

Yes! Epsom salts are good for plant health. It helps with flower and fruit production by encouraging blooming. It also enhances green color in the plants and often encourages plants to grow bushier and lusher.

What stops sunflowers from growing? ›

Not Enough Sun

Less than six hours of full sun per day could also result in no blooms at all. Along with selecting a location with ample light, be sure to plant even shorter varieties in spots where larger plants won't throw shade.

What do you add to sunflower soil? ›

Sunflowers thrive in slightly acidic to somewhat alkaline soil (pH 6.0 to 7.5). Sunflowers are heavy feeders, however, so the soil needs to be nutrient-rich with organic matter or composted (aged) manure. Or, work in a slow release granular fertilizer 8 inches deep into your soil.

How often should you fertilize sunflowers? ›

Pour several gallons of properly diluted fertilizer into the moat every week. Sunflower roots can grow to 4 feet below the soil surface. Avoid pouring fertilizer directly on the stems, since this can cause them to rot.

Can sunflowers get too much sun? ›

Yes, sunflowers love the sun. However, it works only if the temperatures are right. Although they grow even if the temperatures hike up to 30°C, they will begin to wilt after that. Use a green shade net or something similar to prevent the plants from scorching sunlight.

What temperature do sunflowers thrive in? ›

Optimal temperatures for growing sunflowers are between 70 and 78 F. Still, they tolerate high heat as long as their moisture needs are met.

Should I put down fertilizer at night or morning? ›

Fertilizing your lawn in the morning enables you to take advantage of cooler temperatures and morning dew to reduce the risk of burning the grass. As you spread the fertilizer and water it in, the nutrients will have the best chance of reaching the roots and being absorbed quickly.

Can you use too much fertilizer? ›

Too much fertilizer (applied too often or too much) can burn or desiccate roots, ultimately killing the plant. Too much fertilizer can also be harmful to the environment. But, fertilizers do a lot of good by providing macro and micronutrients that enhance the health and performance of plants.

What month should I apply fertilizer? ›

Timing: Apply early spring lawn fertilizer once between February and April, when your grass is starting to green up and begin to actively grow (around the time your lawn first needs to be mowed).

What is 10 15 10 fertilizer good for? ›

Famous "7 drops" formula! Schultz® All-Purpose Liquid Plant Food 10-15-10 is a concentrated product designed to feed all kinds of indoor plants, outdoor plants, flowers and vegetables. Perfect for transplanting, repotting and rooting.

What is the average sunflower yield per acre? ›

Typically, the average oilseed sunflower yield of an experienced farmer in fertile soil range from 2.3 to 2.5 t/ha (2050-2230 lbm/acre). These numbers are decreased when the crop grows in dry conditions without irrigation and few rainfalls, reaching 0.7-2.0 t/ha (624-1784 lbm/ac).

Do sunflowers deplete the soil? ›

The only difficulties that surround growing sunflowers are the demand for direct sunlight and the depletion of soil nutrients. Sunflowers deplete nutrients much more rapidly compared to other plants, which may cause some problems if planted in a garden or flower bed.

What month do you plant sunflowers? ›

When to Plant Sunflowers. Plant seeds after the danger of spring frost has passed and the soil temperature is at least 60 degrees. This will be between March and May, depending on where you live.

Do sunflowers like sugar in their water? ›

Add 1 teaspoon of sugar, 2 tablespoons lemon juice, and/or 1 tablespoon of vinegar to the water to keep your flowers looking vibrant and healthy. This helps delay sunflowers from wilting. Make sure your sunflowers are not exposed to direct sunlight, cool drafts or heat.

Do deer eat sunflowers? ›

Are Sunflowers Deer Resistant? Sadly, for those with sunflower gardens, your garden and flowers aren't resistant to deer. These animals love the leaves of sunflowers and if they are hungry enough, they will also devour the flowers.

Should I cut off dead sunflower heads? ›

To prevent reseeding, remove spent sunflower heads before they go to seed. Alternatively, leave the flowers on the plant if you'd like to collect seeds for future planting or to save as food for wildlife. Frequent deadheading results in healthy, full sunflower plants.

Why are my sunflowers flopping over? ›

Not Enough Water. If your big ol' sunflower seed heads are drooping, that is usually a signal of the end of their growth cycle, not a sign of dehydration. But younger seedlings, and even midsize plants, may hunch over because they're not getting enough water.

When should I cut off my sunflower heads? ›

Once your sunflowers have died back completely and the backs of the blooms are brown, it's time to harvest. You'll also notice the seeds are plump and somewhat loose. Cut the stalk with sharp scissors or pruners, about one foot down from the flower head, and place in a container that can catch any loose seeds.

Do sunflowers ever stop growing? ›

When do sunflowers stop growing? Sunflowers stop growing when the flowers begin turning to seed. During this phase, the stalks turn from green to yellow and then brown, and the flower heads start facing the ground instead of east.

Does cutting sunflowers encourage growth? ›

If you want a longer flowering season, plan to deadhead sunflowers. Cutting back the spent blooms encourages new flower shoots to grow. What is this? If you'd prefer to have sunflower seeds for roasting or future planting, do not cut the spent sunflower heads until they are dry and brown.

How do you grow sunflowers in MN? ›

  1. Direct seed sunflowers after all danger of frost has passed.
  2. Plant seeds one inch deep. For varieties that are 2-5 feet tall, leave about 6 inches between them. Space taller sunflowers at least 1' apart and giant sunflowers 2' apart.
  3. Seeds germinate within 7-10 days.

Why do sunflowers need so much water? ›

Newly planted sunflowers need damp conditions, especially during germination, but established sunflower plants need about one inch of water per week. Underwatered sunflowers will not grow large or bloom, and the plants may droop and appear wilted. Overwatered sunflowers are susceptible to root rot.

How long do sunflowers live? ›

Quick Guide
Symbolism:Adoration, Longevity
Native Origin:North America
Blooming Season:Summer, Fall
Average Life:1 to 2 Weeks

Do sunflowers like eggshells? ›

Plant out in a sheltered position once the risk of frost has passed. Sunflowers like to grow in a rich soil. Protect them as best you can from slug and snail damage, by using copper bands, broken eggshells, or any other organic slug control methods.

Does milk help sunflowers grow? ›

Got milk? Use it in your garden. The beverage isn't just good for the human body, but it's beneficial for plants, too. Milk serves as a fertilizer for your garden to help plants grow, as well as has antifungal and pesticidal attributes.

Can I use leftover coffee to water plants? ›

It's okay to water plants with leftover coffee or to add coffee grounds to the compost pile but learning when and why to use coffee in the garden will protect your plants. Only use black, unflavored coffee with this method to offer plants a source of nitrogen which can fertilize certain indoor and outdoor plants.

Do sunflowers need a lot of phosphorus? ›

Sunflowers use low levels of phosphorus, so applications of 40 to 60 kilograms of P2O5 per hectare is usually enough to replace off-take by the crop and maintain soil levels.

What helps sunflowers grow faster? ›

Sunflowers need full sun; see 6-8 hours of direct sunlight per day – the more the better if you are trying to grow them to their maximum potential. Choose a well-drained location, and prepare your soil by digging an area of about 2-3 feet in circumference to a depth of about 2 feet.

What is 5 20 20 fertilizer good for? ›

Remember, 5 – 20 – 20 is a starter fertilizer that used to establish a new lawn. This fertilizer contains a small amount of Nitrogen. A new lawn needs extra Phosphorous and Potassium to develop strong roots and resist disease, however these still need a small amount of Nitrogen for growth.

What is 30 10 10 fertilizer good for? ›

A high phosphorus fertilizer that promotes fruiting and blooming on ornamental and fruit trees, flowering plants and vegetables.

What is 25 5 15 fertilizer good for? ›

Best as a continuous feed for heavy feeding plants in moderate to warm temperatures. Micronutrient levels are comparable to peat-lite formulas. Can be used as a nutrient booster for great green-up for almost all varieties.

Do sunflowers like Epsom salt? ›

Yes! Epsom salts are good for plant health. It helps with flower and fruit production by encouraging blooming. It also enhances green color in the plants and often encourages plants to grow bushier and lusher.

Do sunflowers need a lot of water? ›

Although sunflowers require a lot of water to germinate, they only require an inch of water per week during the growing season. Use a watering nozzle to easily water once a week until the top 6 inches of soil is moist.

What not to plant next to sunflowers? ›

Hyssop. Hyssop is also a known plant to avoid pairing with sunflowers. These plants are both large and will likely require too much space and water—taking away from your sunflowers.

Can you overwater sunflowers? ›


Sunflowers, in particular, hate wet feet. They can't stand excess water and are very susceptible to root rot. They do boast of deep roots, though. So it makes sense to give them a deep watering regularly, but providing excess water every day is a sure-fire way to kill them.

What month do sunflowers bloom? ›

When do sunflowers bloom? Annual sunflowers bloom during summer and into autumn. Sow new plants every few weeks and you'll enjoy non-stop flowers until the first frost. Perennial sunflowers bloom for a period of 8-12 weeks with some beginning as early as July and others finishing as late as October.

What month are sunflowers harvested? ›

Harvesting Phase

Your seeds should be ready to harvest within 110 to 125 days after you planted the flower. This means that if you planted your seeds in May, your sunflower will die in early or mid-August and you should have ready-to-harvest seeds in late-August or September.


1. Crop Hour: Weed Control Programs in Sunflowers; Updating Sunflower Fertilizer Recommendations
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2. Nuseed Sunflower Breeding and Marketing
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3. What I've Learned About Cosmos and Zinnias for U-Pick Flowers
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4. Nuseed U.S. & Canada - Sunflower R&D HO hybrids
5. MAC 2021 - Observations About Sunflower Production
(UM - Faculty of Agricultural and Food Sciences)
6. Techniques for Planting No-Till Sunflowers


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