Fertilizing A Sunflower – When Should I Fertilize Sunflowers

Fertilizing A Sunflower – When Should I Fertilize Sunflowers

By: Tonya Barnett, (Author of FRESHCUTKY)

Sunflowers are a popular choice for the summer garden. These easy-to-grow flowers are especially loved by kids and beginner gardeners. With so many different varieties to choose, selecting what cultivar to grow may be the most difficult part. Regardless of the selection, many growers are eager to learn more about how to grow the best sunflowers possible. This includes becoming more familiar with sunflower fertilizer requirements.

Should I Fertilize Sunflowers?

Like any plant in the home landscape, deciding how and when to begin feeding sunflower plants will be largely dependent on conditions in the garden. Whether growing sunflowers commercially or in a small row in the backyard, these plants will require ample nutrients. 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 wide range of micronutrients will all need to be present in the soil in order to obtain the best results.

Fertilizing A Sunflower Plant

Many garden soils are healthy enough to support the growth of sunflowers, but having the soil tested can help growers ensure that the sunflowers are grown in nutrient rich medium. When it comes to the fertilization of sunflowers, nitrogen is extremely important.

Fertilization of sunflowers with added nitrogen will contribute to the overall green growth of the plant. Fertilizing a sunflower with nitrogen will increase the height of the plant too. This may be especially important for home gardeners who choose to grow giant varieties of novelty sunflower. Excessive amounts of nitrogen, however, may be detrimental to the plant in that it can limit blooming.

Sunflower fertilizer requirements can be met in a variety of ways. Growers should choose fertilizers which are best suited for their garden. Slow release granular fertilizers are often a popular option, as they can easily be worked into the soil and deliver nutrients to the root zone of the plants.

Garden fertilizers can be applied throughout the growing season according to the manufacturer’s label instructions. With careful research and minimal investment, growers will be rewarded with beautiful sunflowers throughout the summer and into fall.

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Read more about Sunflowers

Growing Sunflowers: Varieties, Planting Guide, Care, Problems, and Harvest

Jennifer is a full-time homesteader who started her journey in the foothills of North Carolina in 2010. Currently, she spends her days gardening, caring for her orchard and vineyard, raising chickens, ducks, goats, and bees. Jennifer is an avid canner who provides almost all food for her family needs. She enjoys working on DIY remodeling projects to bring beauty to her homestead in her spare times.

Have you ever driven past a field of beautiful sunflowers growing in a row and thought, “I want that in my yard!”?

Think of all of the ways you can use a sunflower. They make beautiful bouquets, and they also produce seeds that make tasty snacks. On top of that, they’re perfect for attracting pollinators.

We can’t forget how many colors they add to your garden, as well.

Here’s everything you need to know to grow your own sunflower patch.

Water Do Sunflower Plants Need?

Sunflowers (Helianthus annuus) grow as annuals, with some varieties only living for two months. They thrive in hot weather with full, all-day sunlight, but they require 34 inches of water annually for best growth. Don't allow the soil to dry out completely in the 20 days before and after flowering, if you are growing sunflowers for seeds. Overhead watering wets flowers and foliage, but very little moisture makes it into the soil and to the roots, so water the soil directly instead. Working compost into the site and covering the soil with mulch can help maintain consistent moisture.

How To Grow Sunflower And Get Increased Yields

Sunflower (Helianthus) is an annual plant that belongs to Helianthus genus and Asteraceae family. Sunflower plant is one of the most important agricultural crops in the world. It is a source of vegetable oil with a high content of micro and macroelements, and is the basis for natural feed, excluding the presence of nitrates and pesticides. Besides, fried sunflower seeds are also popular in the food industry. The homeland of the sunflower is the Southern territories of North America, where its useful properties were appreciated by the aborigines, for which it received the status of a sacred plant called “sun flower”.

In addition to being divided into cultural and wild-growing varieties, sunflower also comes in different types, depending on the seed size, agricultural purpose, maturation of the plant, and the nuances of its cultivation. The most common types of sunflower are confectionery, oilseed, and hybrid.

Confectionery sunflower

Confectionery varieties of sunflower are grown for food after frying or fresh. The seeds are distinguished by their significant grain size, easy separation from the shell, and pleasant taste.

The main purpose of growing oilseed sunflower varieties is to obtain vegetable oil.

The features of this sunflower type are small seed size, great taste, and poor shell separation.

Oilseed varieties are not used in the confectionery industry.

Hybrids are annual plants, which is their main disadvantage. However, they show high yields and versatility, which makes most of them suitable for both oil production and food use.

For the last decade, the production of sunflowers in the world has increased by 80%. The main producers of sunflowers are Ukraine and Russia, producing almost half of the world sunflower seeds. Ukraine produced over 16 million metric tons of sunflower seeds in 2019 – 2020, and Russia – over 15 million metric tons in the same timeframe. In April 2020, Ukraine exported a record amount of sunflower oil. For the first time in the history of its independence, 717 thousand tons of the product were sent to foreign markets.

Use Crop Monitoring in your country to manage your sunflower field.

Sunflower soil and climate requirements are high, compared to other crops. The minimum temperature for germination is 5 °С. During sowing, the soil temperature should be at least 6 °С. Starting from the second half of May, the average temperature should be 15 °C. Heat requirements are especially high during the periods of rapid growth and flowering before ripening (July – September). The optimum temperature for photosynthesis is 25 °C. Seedlings tolerate late frosts down to -5 °C. For sunflower cultivation, areas with frequent spring frosts are not suitable, as well as those in which harvesting is not done until the end of September.

Sunflower is also very demanding on soil moisture. Well-developed sunflower crops consume from 500 to 600 mm of water during the growing season, and the minimum water demand is satisfied at 350 – 400 mm of precipitation. Plants are especially demanding on moisture during bud formation before flowering.

In regions with a continental climate and heavier soils, like chernozems, sunflowers fully utilize the soil water resources accumulated in winter. Due to this, the plants show relative resistance to drought.

Sunflower soil requirements are primarily determined by the properties of its root system and the need for water. Soils with a deep arable layer, good permeability to roots, without compaction of soil and subsoil, with a high useful moisture capacity, are suitable for growing sunflower. They are able to provide plants with moisture and nutrients during the growing season. These requirements are best met by loess soils, loess and sandy loams. On lighter soils, sunflowers can be successfully grown if the humus content is high enough and the roots can use the groundwater.

In terms of predecessors, grains and corn are the best for sunflower. Potatoes and sugar beets are suitable as predecessors only in cases where organic fertilizers were not used, the soil structure is not severely destroyed during harvesting, and the soil is not very dry.

Use Crop Monitoring to help meet the requirements of sunflower plants while growing.

Here are the main stages of the sunflower growth cycle.

At this stage, hypocotyl with cotyledons emerge from seed and grow towards the soil surface. The stage ends when cotyledons emerge through the soil surface.

This is the stage when the plant’s leaves start unfolding. The stage lasts until at least 9 leaves unfold.

This stage starts when 1 extended internode is visible and lasts until 9 or more extended internodes are visible.

3. Inflorescence emergence

At this stage, the inflorescence becomes visible between the youngest leaves. The stage lasts until the ray florets are visible between the bracts, but the inflorescence is still closed.

This sunflower growth stage starts when the ray florets extend and disc florets become visible in the outer third of the inflorescence. Flowering stage ends when most disc florets have finished flowering, and ray florets dry or fall off.

5. Development of fruit

At this stage, the seeds on the outer edge of the inflorescence turn grey and reach their final size. The stage ends when the seeds on the inner third of the inflorescence are grey and have reached their final size.

At this stage, the seeds on the outer third of the anthocarp turn black and hard until there is about 85% of dry matter.

This is the last of sunflower growth stages. The seeds are over-ripe, with over 90% of dry matter. The plant dries out and dies.

Identify and manage these growth stages in Crop Monitoring.

The main tillage is carried out in autumn and is aimed at accumulating and retaining soil moisture. It depends on the predecessor, the degree of infestation, and the types of weeds.
When growing sunflowers after winter grains and after weeds, it is necessary to start land preparation with disc cultivators stubble after harvesting. Plowing of the soil is done to a depth of 25–30 cm.

When preparing land for farming, traditional tillage can be replaced by no-till farming, which consists in deep loosening of the soil to the depth of 30 – 35 cm with chisel-type implements in combination with a heavy disc harrow. Deep loosening contributes to the destruction of the plow sole, better aeration of the soil, and the accumulation of moisture in the autumn-winter period. Soil tillage before sowing should be minimal: early spring harrowing and 1-2 cultivations depending on the sowing time, the presence of moisture in the soil, and weed seedlings.

Sowing planting time depends on the soil temperature. The optimal period is relatively short. On the one hand, the temperature of sunflower germination excludes an early sowing, on the other hand, late sowing leads to late ripening, which in many regions, even with the cultivation of early-maturing varieties and hybrids, causes a decrease in yield. Sunflower can be sown when the soil temperature reaches 8 °C at a depth of 5 cm. The emergence of seedlings is highly dependent on the temperature of the soil. The required sum of temperatures from sowing to emergence is 70 – 80 °C. With the optimal sowing time, seedlings appear in 10 – 15 days.

The longer the period from sowing to emergence, the greater the risk of plant damage by mice, birds, and pathogens. Therefore, it is best to choose not late but not very early sowing dates.

Use Crop Monitoring to help identify the best time for planting sunflower.

Before planting sunflower, it’s necessary to carry out seed treatment to protect the seeds and seedlings from diseases and pests. It will help to obtain healthy seedlings and ensure their uniform distribution over the field to result in high yields.

Plants density varies depending on moisture supply, and by the beginning of harvesting season it should be:

  • In humid forest-steppe regions and adjacent steppe regions – 40 – 50 thousand plants per 1 ha
  • In semi-arid steppe regions – 35 – 45 thousand plants per 1 ha.

When cultivating early-maturing sunflower hybrids, it is recommended to increase their density by 10-15%, but not higher than up to 55 – 60 thousand / ha. The higher the sunflower seed rate, the smaller the row spacing should be. Otherwise, the distance between plants in the row will be too small, which will lead to an increase in plant height and an increase in the risk of lodging.

Sowing of sunflower is carried out with row spacing of 70 cm. The normal sunflower seed planting depth is 4 – 6 cm, 6 – 10 cm in dry conditions, and 5 – 6 cm on heavy soils and in cold spring. The lighter the soil, the deeper you can sow. In more continental conditions, a deeper depth should be chosen.

Identify field productivity zones in Crop Monitoring to distribute sunflower seeds across the field rationally.

Sunflower fertilizer requirements depend on the soil, climatic conditions, productivity of a particular variety, agrotechnical and organizational conditions. Sunflower takes out nitrogen and phosphorus in large quantities in comparison to other crops, and has no equal in terms of potassium use. For the formation of 20 centners / ha of seeds, the plants need 56–58 kg / ha of nitrogen, 22 kg / ha of phosphorus, and 30 kg / ha of potassium. Depending on environmental factors and nutritional conditions of the soil, these values may vary significantly. During the growing season, the sunflower uses nutrients unevenly. A large amount of nitrogen and phosphorus is used before flowering, when leaves, stem, and roots are formed. After that, phosphorus use decreases sharply. Potassium is absorbed by sunflowers almost throughout its whole growing season, but especially before flowering.

Identify filed productivity zones in Crop Monitoring to apply sunflower fertilizers rationally.

In arid steppe regions with deep groundwater, it is recommended to carry out sunflower irrigation in fall to create moisture reserves. The irrigation rate should be 1200 – 1800 m3 of water per hectare. Apart from this irrigation, irrigation during the growing season is necessary for the fullest use of the productivity potential of this crop. The period of the greatest moisture demand of sunflower lasts 40 days. It begins when the diameter of flower buds reaches about 3 cm, and ends when the plants are blooming. It is also preferable to use irrigation installations that provide even distribution of water.

When watering sunflowers, it is advisable to maintain soil moisture during the growing season above 60% of the field moisture capacity, and during the period of increased moisture consumption or in crops with a high expected yield – above 80%.

After the start of irrigation, depending on the need, it should be continued every 8 – 12 days. However, at the beginning of flowering, do not water sunflowers if possible, since there is a high risk of infestation in this phase. After flowering, irrigation can be continued until 50% of green leaves remain.

Here are the most common sunflower pests and the ways to protect the crop from them:

These sunflower worms damage the leaves of young plants, leaving holes or notches in them. However, these pests can cause issues only in case of a heavy infestation.

These pests usually feed on the leaves of older plants. However, the beetles may also damage young plants.

These pests burrow into the plant stems and feed on them, causing severe damage to plants, especially in large numbers.

These pests nibble on the plant foliage. It does not cause severe damage, but large numbers can quickly defoliate plants.

This pest lays eggs inside the flowers. Later, the larvae feed on the flower heads, eventually destroying the plants.

Sunflower pest control

The main step in protecting sunflowers from pests is to keep the field free of weeds and debris. Later planting in June or July can also help. Besides, the use of organic insecticides can be used as well.

Use Crop Monitoring to help access plants health and take measures when necessary.

Here are the most common sunflower diseases and the ways to protect the crop from them:

Alternaria leaf blight

This disease causes dark brown, irregularly shaped lesions on leaves. The plant eventually becomes defoliated and dies. Blight emerges in hot weather and frequent rainfall.

  • Removal of infected leaves
  • Adequate plant spacing
  • Foliar fungicide application

This disease leads to the death of seedlings by causing white cottony growth on leaves undersides. The disease emerges in high humidity.

  • Selection of resistant varieties
  • Seed treatment

This disease usually occurs after flowering and is manifested in large black, irregularly shaped lesions on a stem. Infected plants produce little seed and die prematurely.

  • Crop rotation
  • Selection of resistant varieties
  • Control of stem weevil populations in the field

This disease affects all of the above-ground parts of a plant. Black fungal fruiting bodies become visible on the plant and the infected leaves turn yellow and dry. Disease emergence in high humidity.

  • Adequate spacing between plants
  • Removal of debris after harvest
  • Foliar fungicides application

This sunflower disease affects lower leaves of the plant, causing the leaf tissue between veins turn yellow and brown. The leaves eventually wilt, dry out, and die. The disease is usually spread through contaminated irrigation water or the infested soils.

  • Selection of resistant varieties
  • Avoiding planting in fields known to have been infested

Use Crop Monitoring to help track plants health and act accordingly when needed.

Choosing an optimum sunflower harvesting time is essential for its efficient cultivation. The sunflower ripening phase lasts for several weeks and can be identified by the following criteria:

  • Yellowing of the ray floret
  • Wilting and falling of reed flowers
  • Hardening of the kernel
  • Drying of most leaves.

According to the moisture content of the seeds and the color of the ray floret, there are three degrees of maturity: yellow, brown, and full. In yellow maturity, the leaves turn lemon-yellow, and the biological ripeness of the seeds is 30 – 40%. In brown maturity, the moisture content of the seeds is 12 – 14%. In full ripeness, the moisture content of seeds is 10 -1 2%, the plants are dry, brittle, and the achenes crumble.

Harvesting sunflowers with combines should start when 85 – 90% of plants have reached brown maturity.

Use Crop Monitoring to help determine the best time for harvesting.

An average sunflower yield per acre is around 68 – 75 bushels. The world record sunflower yield of 184.68 bushels per acre was harvested in 2016 in the Kabardino-Balkarian Republic.

The main factors affecting sunflower yield are:

  • Climate and place of planting
  • Irrigation
  • Fertilization
  • Pests, weeds and diseases control
  • Seed quality
  • Sunflower variety

An average price of sunflower per hundred weight (CWT) is $17 in 2019. The main advantages of sunflower cultivation are the stable and high demand for it and its relatively high prices on domestic markets of its producers. Such relative stability and minor fluctuations in the market value of sunflower give the future prospects for its cultivation and affect its price.

Here are the main practices that will help to increase the yield of sunflower

The best strategy is to start planting as soon as the soil is ready, based on the tests you have carried out.

2. Knowing the seeds yield potential

Choose the seeds with the highest yield potential for planting.

3. Carrying out field scouting

Scouting gives you a chance to assess soil conditions, notice the spread of weeds and diseases, and check that the crops are growing healthily.

Fertilization helps to provide the seeds with essential nutrients, facilitate plant growth, and protect them from pests and diseases, which will result in higher yields.

5. Planting high-quality seeds

Consider using hybrid seeds that are naturally inclined to be stronger, grow faster, and with greater efficiency.

Use Crop Monitoring to manage your field and increase sunflower yield.

Harvesting Sunflowers & Their Seeds

How you harvest your sunflower and its seeds will depend on what you plan on doing with them. For the most part, people like cutting sunflowers for bouquets or harvesting the seeds.

Cutting Sunflowers for Bouquets and Vases

  • Do this in the morning. You don’t want to do so in the afternoon because the heat will cause it to wilt.
  • Cut the main stem then immediately dip it into water.
  • Make sure to be careful and gentle with them. This reduces the risk of bruising or damage.
  • Ideally, you want to use a tall vase or container so that it supports their stem.
  • Enjoy your bouquet. They should last a week or a little longer than that

Harvesting Sunflower Seeds

The best time to do this is at the end of the season. Here, you have a few choices on what you want to do with the seeds, they include

Eat them as a snack

This requires the most work since you’ll need to rinse and dry them before being able to do anything with the seeds.

  • Wait until your flowers’ heads dry and start turning down to face the ground.
  • Cut off the flower head along with about 6 inches of stem.
  • Lay the head on a flat surface, then start removing the seeds.
  • Finally, hang them up to dry. If you’re hanging them outdoors, make sure to keep them protected from birds. You can likewise hang them indoors.

Replanting Sunflower Seeds

To replant them, you’ll want to store them in an airtight container and keep them away from moisture. Somewhere like your pantry where it’s dry and cool would be a perfect place to put them until you’re ready to plant them in the ground.

Using Sunflower Seeds as Bird Feed

Using the seeds a bird feed involves the least amount of work. That’s because you can just leave them for the birds to come feed on them.

Watch the video: Fertilizing Sunflower with Phosphorus, Potassium, and Micronutrients