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Why Are My Sunflower Leaves Turning Brown

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Sunflowers are stunning plants that play a significant role in the global food economy. Sunflower oil is essential for many food ingredients. So naturally, the oil cake leftover after making oil is an essential component of many animal feeds, including rations for chicken, pork, beef, and lamb.

We humans love sunflowers in our gardens beside their advantages for the food supply. So, if you have a sunflower plant, you must know how to care for them. Occasionally your plant may show brown leaves, which could have you asking, why are my sunflowers dying? Sunflower leaves turn brown for many reasons, and as this occurs, the overall health of the plant can be affected.

In our guide, you can learn more about why your sunflower leaves can turn brown during the growing season. By the end, you’ll know more about how sunflowers grow and what’s needed to help them remain healthy. (Read Will Winter Rye Reseed Itself)

Sunflower Leaves Turning Brown

Why Are Sunflower Leaves Turning Brown?

Your sunflowers are dying for several distinct reasons. This could affect both container-grown sunflowers inside and outdoor garden varieties:

  • Nitrogen deficiency
  • Lack of space for roots to spread
  • Need more light
  • Watering problems
  • Too much heat
  • Pests and disease
  • Poor Quality Soil

When sunflowers lose petals, turn yellow and brown, or lose leaves, many gardeners panic. Keep reading to learn why sunflowers die and what you can do to save them.

Common Sunflower Plant Problems

Sunflowers are easy to grow, although susceptible to various problems that can cause them to die. For example, sunflowers like wetness, yet new plants are vulnerable to fungal withering without enough water. In addition, sunflowers are attacked by soil-dwelling fungi, which spread upward to cause dark brown patches on the stems and leaves of new plants.

Sunflowers need room to grow deep roots, plenty of nutrition, well-draining soil, water, and routine maintenance. Giving your sunflowers some TLC and the right conditions is the difference between a beautiful garden and wilting flowers.

Nutrient Imbalance

All plants need nutrients for growth. Plants, however, struggle whenever there is an excess or a lack of nutrients. Sunflowers need an amount of nitrogen in their soil to grow tall and healthy.

The size of a sunflower, the yield of sunflower seeds, and the number of leaves all depend on how much nitrogen is present in the soil. Sunflowers are a deep-rooted plant, so adding fertilizer should keep them healthy and happy. In addition, add potash and potassium, besides just adding nitrogen.

Balance is critical because too much nitrogen in sunflowers can lead to fewer flowers. Check your young sunflowers to see their variety, such as perennial or annual, and fertilize sunflowers using a low-nitrogen fertilizer.

Add fertilizer to the soil before planting to give your sunflowers a good start. However, sunflowers’ leaves may turn yellow and drop off if insufficient nitrogen is present or you skip fertilizing your plants. When there is insufficient nitrogen in the soil, most plants will exhibit stunted growth and thinner stems. (Learn How To Kill Mushrooms In Mulch)

Sunflower Plant Problems

Roots Need Space

If you aren’t growing a dwarf variety of sunflowers indoors in a pot, give outdoor sunflowers plenty of space in a garden bed so their roots can spread out and establish themselves.

Before planting, the soil must be examined, turned over, and any obstacles removed. A problem with or obstructing a sunflower’s root system can cause stunted growth, competition for nutrients and water, and health issues. A potted sunflower may die if planted by too many competing plants, as they won’t have enough space, food, or water to thrive.

More Sunlight

Like their namesake, sunflowers require lots of sunshine to grow into healthy, tall, colorful plants.

If you take the chance of growing sunflowers indoors and don’t provide them with enough light each day, or if you grow sunflowers outdoors in heavy shade, your sunflower might wither and give.

For the best results, sunflowers require anywhere from 6 to 12 hours of direct sunlight.

Watering Problems

Because sunflowers have deep roots, they require deep watering. However, leaving them sitting in excess water can cause root rot, so resist the urge to supply too much water.

The sunflower’s stem may also rot or turn brown at the base, so ensure the soil has good drainage. Ensure the pots have suitable drainage holes to lessen the chance indoor sunflowers will be overwatered.

The most frequent reason for plant death is overwatering. Of course, beginners harm plants by overwatering, yet you’ll find sunflowers dislike wet feet. When the topsoil is dry, your sunflowers will thank you for watering the roots, not the whole plant.

Too Much Excessive Heat

Sometimes, it’s possible to have too much of a good thing. For example, sunflowers may suffer scorched leaves, wilted flowers, drooping, and death if exposed to excessive heat.

Rotate potted sunflowers to ensure they receive enough sunlight, but avoid keeping them only in southern or western exposure, as these temperatures can get too hot. Sunflowers planted outdoors should be strategically placed to provide relief as partial shade during the day.

They can grow in temperatures as high as 30°C, but the sunflower leaves wilt above that. Use a green shade net or something similar to protect the plant leaves from the sun’s harsh rays. You could also use a fan or an air conditioner to lessen the heat indoors.

Pests & Disease

Sunflowers can be plagued by pests and diseases, which can cause them to change from a blooming beauty into a perplexing sight.

It’s time to act when you see spots or patches on the leaves or petals or when the stem and leaves of a sunflower turn brown or black due to rot or mold. First, remove damaged leaves and pests by removing dead or damaged flower heads and disposing of them rather than throwing them on your compost pile.

Leaves can develop holes due to pests like cutworms and sunflower beetles. In addition, the stem and flowerhead of plants are harmed by sunflower borers and sunflower moths, which are a pain for sunflowers. (Learn How To Tell If Zucchini Is Bad Inside)

Poor Soil Conditions

For a sunflower, it is crucial to fertilize the soil or use good soil rich in organic matter and nitrogen, which is not overly complicated, so that root systems have a tough time developing and have a desirable pH level.

Sunflowers can survive in pretty much any soil, but it is best if the pH ranges from 6 to 7.5. Mulch sunflowers early when the plants reach about 6-8″ in height and use organic matter to help balance the pH.

Why Is My Sunflower dying?

Despite being simple to care for, your sunflower plants’ leaves could suddenly start falling. Sunflowers bounce back from setbacks more typically than you might expect. However, you might need to intervene if you notice the plants wilting and turning yellow without apparent cause.

Sunflowers can die from severe damage from mold, mildew, fungi, insects, or abuse and even pass away. Dying sunflowers can show stunted growth, dropped leaves, leaves that have turned yellow, brown, or black, and shriveled petals on the flower head.

You might save the plant before it is too late, depending on how severe the symptoms are for the sunflower and what the cause is. Sunflowers that die naturally can be composted and used again, but sick sunflowers should be thrown away.

Reasons For Sunflower Leaves Turning Brown

Leaf Disease

There may be a few reasons sunflowers are prone to various diseases, such as high soil pH. Therefore, you must reduce the soil’s acidity to a level your sunflowers need. Plants with the disease may attract pathogens, leading to more problems.

The pathogens stay there until the plant reaches maturity and cause brown spots on the leaves. Then, the entire plant can be infected, which causes irreparable damage. Using an organic fungicide to get rid of pathogens is one way to manage them.

A change in the climate can also bring on leaf diseases. For instance, hot temperatures and high carbon dioxide levels have a detrimental multiplicative effect.

Fungal Wilting

Insufficient watering can give rise to fungal wilting of your plant. On the other hand, a plant without water doesn’t necessarily have fungal wilting, though chances are high.

Monitor your plant, and after a couple of days of adequate watering, if brown spots remain on the leaves, it shows your plant is suffering from fungal wilting.

These fungi can attack a plant from top to bottom, causing brown spots on leaves and stems. To help prevent this, ensure your young sunflower has sufficient water without overwatering.

The only solution for infected plants is to remove them and not use the soil for other plants, which could pass on the infection.

Reasons For Sunflower Leaves Turning Brown

Septoria Leaf Spot On Sunflower

Septoria helianthus can attack your sunflower garden, and you’ll find younger sunflower plants are more prone to this fungus. You can spot the circular and angular, dark brown spots or gray shapes that appear to be water-soaked yet are the fungus.

Check your sunflower seeds before planting, and even dry seeds are susceptible. Once your plants are growing, the fungal growth affects young, over-watered plants and can also start from heavy rains.

It is advisable to prune affected leaves and then wash your hands and equipment before touching healthy ones. You can also apply organic or chemical fungicides.

Beetle Damage

Insects like beetles may turn your sunflower brown in the summer. Closely observe your plant to see moving spots. You can see these insects have brown heads and white bodies. Carrot beetles are typical. This problem is more likely to arise with newly planted sunflowers where leaves and roots are affected.

Use beetle-specific insecticides or broad-range organic insecticides to eliminate this problem. You can also use some dishwashing soap in water with a dash of neem oil to eliminate many pests on the sunflower leaves.

Downy Mildew And Rust

Downy mildew is another fungus on the underside of sunflower leaves, which can also spread to buds and stems.

Gray, purple, and light brown spots show fungal growth. For example, rust is a fungal disease that causes spots on the underside of sunflower leaves, and to treat these; you can use broad-spectrum fungicides.

How Long Do Sunflowers Last?

The length of a sunflower’s bloom varies depending on the variety and when the flowers were planted, but it typically lasts two to three weeks.

Cut flowers may remain fresh for up to three days. Annual sunflowers die after a year and won’t return, but smaller varieties are typically great for growing indoors and will last for years. (Read Citrus Trees Are Angiosperms And Dicots Guide)

How Do You Revive a Dying Sunflower?

Indoor sunflowers that are struggling may need to be repotted, so they have more space, given water if the soil has been parched too long, or given fertilizer for a boost of nutrients. To thrive, outdoor and indoor sunflowers need enough sunlight, mulch, and regular removal of damaged leaves, pests, and dead or damaged flower heads.

Under the leaves, check for pests. Aphids, mealybugs, spider mites, and thrips are common pests. If you find bugs, buy or make a pesticide. Remove damaged leaves and pests by removing dead or damaged flower heads and disposing of them rather than throwing them on your compost pile.

As mentioned, your sunflowers may have problems. The plants will recover if you catch them in time. Without repairs, the plant can deteriorate. If you have a perennial variety, you’ll need to protect it over the winter.

Why Are My Sunflower Leaves Turning Brown