Why Are My Sunflowers Dying? [And How to Save Them]

Sunflowers are a beautiful and beloved flower that is visually striking and rich with symbolism. People adore this sun-loving flower for its vibrant petals, edible seeds, and how they follow the sun while reaching dizzying heights above 10 feet or more. However, what if your sunflowers are showing signs that they are dying? When a sunflower begins showing unwanted color changes in their petals and stalk, is suddenly drooping and withering away, or pests are wreaking havoc on leaves and petals, an intervention is necessary. We have researched to find out everything that causes sunflowers to die.

There are more than a few reasons that your sunflowers are dying. Both indoor sunflowers growing in pots and sunflowers in outdoor gardens may be susceptible to the following:

Not enough nitrogen

Not enough space for the root system

Needs more sunshine

Overwatering

Overheated

Pests and Diseases

Poor Quality Soil

When your sunflowers are looking less than their best, complete with dropping petals, stalks and stems turning yellow and brown, or leaves falling off, many gardeners may go into panic mode. Before throwing in the towel, keep reading to learn typical reasons why sunflowers may be dying and what you can do to keep your sunflowers happy, healthy, and lovely.

Why Are My Sunflowers Dying? [And How to Save Them]

Common Problems for Sunflowers

Sunflowers are a pretty easy flower to grow for novice and experienced gardeners, but they are still susceptible to various problems, which can cause them to fall sick and perish. Not only is it vital to give sunflowers enough space to grow established root systems so they can reach toward the sky, but they also need plenty of nutrition, well-draining soil, adequate water, and routine maintenance. Giving sunflowers proper TLC and an environment in which they can thrive may be the difference between a beautiful garden worth envying versus worrying over wilting and dying flowers.

Lack of Nitrogen

To grow tall and healthy, sunflowers demand a significant amount of nitrogen in their soil. The amount of nitrogen in the soil will impact the size of a sunflower, the seed yield, and leaf development. Because sunflowers are a deep-rooted plant, it is advisable to administer fertilizer to keep them well-fed and happy. In addition to nitrogen, sunflowers need potash and potassium.

Balance is critical, as giving sunflowers too much nitrogen can lead to fewer flowers. Look into whether the variety of sunflower you are growing is perennial or annual, and start with a low-nitrogen fertilizer. You will want to add fertilizer to the soil before planting to give your sunflowers a good start. If there is too little nitrogen or you forego fertilizing a sunflower, their leaves may begin to turn yellow and will drop off. Most plants will display stunted growth and thinner stems when nitrogen in the soil is lacking.

Roots Need Space

Unless you are growing a dwarf variety of sunflowers indoors in a pot, you will want to give outdoor sunflowers plenty of space in a garden bed so their roots can spread out and establish themselves. It is critical to check the soil, turn it over, and remove any obstacles before planting. If the root system of a sunflower encounters a problem and is blocked, it can lead to stunted growth, competition for nutrients and water, and lead to health problems. A potted sunflower that is planted with too many competing nearby plants may die if they can't get enough room, water, or food to thrive.

More Sunshine Please

Close up of withered sunflower on the field

Sunflowers, like their namesake, need plenty of sunshine to grow healthy, tall, and vibrant. If you take the chance of growing sunflowers indoors and do not give them enough light each day, or you grow sunflowers outdoors in dense shade, your sunflower might wither away and perish. Sunflowers need anywhere from 6 to 12 hours of strong sunlight to become their best.

Overwatering

Sunflowers are a deep-rooted plant, so they need to be watered deeply and thoroughly. Resist the urge to overwater a sunflower, which can lead to root rot. Also, the base of the sunflower's stem may begin to show signs of rotting or become brown. Make sure that your sunflower is in soil that drains well. Indoor sunflowers should be placed in pots that have drainage holes to reduce the chance of the flower perishing from being drenched.

Too Much Heat

Withered Sunflowers Ripened Dry Sunflowers Ready for Harvesting.

Sometimes there can be too much of a good thing, as sunflowers can suffer from scorched leaves, wilted flowers, drooping, and eventual death if they are exposed to too much heat. Be careful to rotate potted sunflowers, so they get enough sun, but avoid keeping them exclusively in southern or western exposure when temperatures can become excessive. Outdoor sunflowers should be planned regarding their placement, so they receive some welcome relief in the form of partial shade during the day.

Pests & Disease

Pests and diseases can riddle a sunflower and quickly transform it from a blooming beauty into a bewildering sight. When you notice spots or patches on leaves and petals, or the stem and leaves of a sunflower become brown or black because of rot or mold, it's time to intervene. Pests like the sunflower beetle and cutworms can cause holes in leaves. Sunflower borers and sunflower moths are also a pain to sunflowers, damaging the stem and flowerhead of plants.

Poor Soil

It is essential to fertilize the soil for a sunflower or use soil that is quality, filled with organic matter, nitrogen, is not overly hard, so root systems have a hard time developing and have a desirable pH level. Sunflowers can pretty much tough it out in any soil, but it is better if it has a pH level of 6 to 7.5. Also, sunflowers have deep root systems and have a high demand for nutrition to grow to their fullest potential and height for their type.

How Do You Know When a Sunflower is Dying?

Sunflowers can become severely damaged and even die because of mold, mildew, fungi, insects, or abuse. A sunflower will signal that it is dying with stunted growth followed with dropped leaves, the leaves and stem turning yellow, brown, or black, and the petals on the flower head shriveling up. Depending on how severe the symptoms are for the sunflower and the cause of its problems, you might be able to save the plant before it is too late. Sunflowers that die of natural causes can be safely placed in a compost bin and repurposed, but diseased sunflowers should be discarded.

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How Long Do Sunflowers Last?

The bloom of a sunflower typically lasts for two to three weeks, depending on the variety, and when you planted the flowers. Cut flowers may last two to three days or longer. Smaller varieties of sunflowers are usually great for growing indoors and will last for years, but annual varieties of sunflowers will die after a year and not return.

How Do You Revive a Dying Sunflower?

Ripe sunflower flower in the field. Collection of seeds for the production of sunflower oil.

Indoor sunflowers that are struggling to hold on to life may need to be repotted, so they have more space, given water if the soil has been left parched for too long, or be given fertilizer for a boost of nutrients. Outdoor sunflowers and indoor sunflowers should be given an adequate amount of sunlight to thrive, in addition to practicing things like mulching, removing damaged leaves and pests on sight, and removing dead or damaged flower heads from the stem. Ensure that your sunflower is protected in the winter if it is a perennial variety so it can return next year.

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When is the Best Time to Fertilize Sunflowers?

Sunflowers grown outdoors do well when you apply a granular fertilizer that is slow-releasing and reaches the root system deep in the soil. Before planting a sunflower, you should fertilize the soil, and apply fertilizer and water it weekly as needed until it establishes itself. When you are ready to usher sunflowers into a dormant state, you will want to cease adding fertilizer to the soil.

Does My Sunflower Need Protection in the Winter?

Sunflowers can suffer irreparable damage to the stems and root system in the winter if not protected. It is advisable to safeguard sunflower plants and seeds against predators, strong winds, bitter temperatures, and frost so they can produce next year if they are annual and left seeds behind that will germinate, or if you are growing a perennial variety.