Why Are My Sunflowers Closing Up? + [Some Maintenance Tips]

why are my sunflowers closing up

Why are my sunflowers closing up?

When sunlight is inadequate, flower formation is poor, meaning no flowers, drooping, or even closed flowers of a sunflower plant. When it comes to overall care and maintenance, sunflowers are not very demanding. Nonetheless, sunlight isn’t the only requirement for a healthy sunflower that you should uphold.

If you are unhappy, get a sunflower! Sunflowers have tall stems and bright, yellow flowers. Aside from their beauty, the seeds are very nutritious. While sunflowers thrive in full sun, this resilient plant can also survive in dry climates and many soil types.

Remarkably, sunflowers bloom in summer and early fall. Read on to understand more about this plant and make it useful for your daily life.

Also check – Why are my sunflowers turning white?

Sunflower’s Life Cycle

There are five stages in the life cycle of a sunflower. The germination phase is the first step of the sunflower’s life. Following is the vegetative phase when the plant leaves shoot. Immediately after, the reproductive stage kicks in, and the flower bud develops. The blooming phase then comes in when the flower fully blooms. At the end of the season, those interested in the seeds can harvest them for personal use.

Germination Phase

Usually, germination begins right after planting the seeds. In sunflower, the germination phase takes place for a maximum of 8 days. So what happens in germination?

The root system will develop from the seed at this stage while the shoot emerges above the ground. The shoot comes above the soil, searching for sunlight because it’s a basic necessity in every plant growth.

Furthermore, the germination of sunflowers takes place from mid-April-late-May, reliant on the time of planting of the seeds.

Vegetative Phase

When germination is through, and the sunflower is secure in the ground, the vegetative phase begins. However, at this point, your sunflower remains a seedling about 13 days after breaking the ground. This stage is called vegetative emergence.

So, when the plant develops the first leaf about 4cm long, it gets into vegetative stage one. Consequently, when another leaf shoots, and they are now two measuring about 4cm, the sunflower continues to vegetative stage 2 and so forth.

When you decide to plant your sunflower in either April or May, expect the vegetative phase to occur in May or the beginning of June.

Reproductive Phase

The reproductive phase begins when a flower bud shoots among so many leaves. At first, the bud will appear like a star, but after this reproductive phase is through, it will change into the tall stemmed, bright yellow-flowered plant you are so familiar with.

A sunflower takes nearly 30 days to bloom as expected fully. Typically, the reproductive phase starts in June and ends in July or August.

Blooming Phase

This stage consists of the beautiful yellow sunflower for close to 20 days. In the blooming phase, bees and birds enjoy the opportunity to pollinate the flower and fertilize the seeds. Most importantly, you will know the seeds are starting to ripen when the back of the sunflower head becomes yellow.  

If you are planning to use sunflower blooms, the blooming phase is the perfect time for that. So, you can go ahead and cut to vase and decorate with them or even gift them to a loved one.

Harvesting Phase

If you have personal plans to use the sunflower seeds, the harvest phase is the right time to have them. Therefore, you should wait till the sunflower turns brown and droops.

Afterward, cut the stem about 4 inches from the head of the sunflower. Remember to store the sunflower head inverted in a dry and breathable bag.  

Sunflower seeds take around 110-125 days to be ready for harvesting. So, if you planted the seed in May, the sunflower will die back in August for the seeds to be ready by the end of August or early September.

As annual plants, sunflowers require yearly replanting.

What Makes A Sunflower To Die? [Why are my sunflowers closing up?]

When people talk of problems their sunflowers are facing, usually the source revolves around fundamental issues. In short, it will be best to identify the problem before treating your sunflower or any other plant.

Generally, indoor-growing sunflowers using artificial lights are less resilient than those growing outdoors in the bare and direct sun. Perhaps, your fertilizer could be the issue causing toxicity or having a nutrient deficiency. Whatever the reason, you need to establish and understand the problem as the first step.

Below are some common problems that could be ailing your adorable sunflowers. Read on.


There are many causes for plants to die, but the common one is overwatering. Overwatering is a frequent mistake for amateur gardeners because they think that a little extra water is a way of extra care. The truth couldn’t be further from the truth because, in this case, sunflowers hate wet feet.

Sunflowers loath excess water because they are mainly vulnerable to root rot even though they have deep roots. Preferably, deep watering is ideal for their healthy growth but avoid overwatering in the schedule.

Moreover, it would help if you only watered your sunflower when the topsoil feels dry to touch.


Conversely, there are rare cases of a dead sunflower plant due to underwatering. Why is that?

Typically, sunflowers prefer little water for their growth. However, if you leave them without water for an extended period, the plants will die prematurely. So, always ensure you have a backup watering routine if your life involves staying away from the plants for a long time.

Nutrient imbalance

Every plant requires the right type and amount of nutrients to grow. Still, plants also struggle when there is lack, excess, or poor nutrients like humans do. Above all, nitrogen is the essential nutrient in the growth of many plants, sunflower included. What’s more?

With adequate nitrogen, the foliage looks green and lush. But, deficiency in nitrogen causes weak stems that break or bend easily. Also, the leaves discolor to yellow leading to the plant’s death.

Nevertheless, too much nitrogen is also not good. In this case, the leaves overgrow, which inhibits the formation of flowers. This is because the plant spends more energy from the nutrient in making the leaves which the flowers have nothing to grow from.

So, if your sunflower is having problems, check how you feed the nitrogen in case there’s an imbalance that needs correction immediately.

Most importantly, after identifying the problem, you should apply an all-inclusive feed with both macro and micronutrients.


Just like its name and shape suggests, the sunflower must have the sun. Sunflowers crave and live for sunlight every day.

That’s why growing sunflowers indoors is a challenging task since you must provide them with sun-like lighting to achieve the desired growth. However, as difficult as this seems, it is possible.

Still, too much of something is poisonous. So, excess sunlight in combination with high temperatures is also a problem for the sunflowers.

You will find them closing up, drooping, and even wilting, eventually dying.

Excessive Heat

Of course, sunflowers love sunlight. However, this is only healthy with the right amount of temperatures. Although they are tough to endure even extreme temperatures of 30°C, they will not last and start wilting immediately after.  

Ideally, it would be best to prevent your sunflower from the scorching sun that hikes the temperatures by using a green shade net. Similarly, it would also help if you use either a fan or air -conditioner to reduce the heat indoors.


When you see sunflower plants having blooming troubles, you should also examine the presence of insect pests such as sunflower midge. The sunflower midge is expected on the wild sunflowers across the northern Great Plains and South Texas.

However, the pest is now invading planted sunflowers. This delicate adult fly hides in the soil as a larva during the winter season. It emerges in late July to lay eggs on the clusters of growing sunflower sprouts.

The sunflower midge hides under the bud bracts or in the center of the bud. After laying the eggs, the larva hatches out two days later. They grow inside the sunflower blossoms while feeding on them. As a result, the buds start swelling from the inside due to all the larva activity. Still, they can affect the flower head to an extent where no blooms will be present.

How Can You Tell If Your Sunflower Is Dying?

As observed above, several problems can affect your pretty sunflowers. Luckily, prompt identification and treatment of these problems will cause the plants to bounce back. Failure to do this, your sunflower will die right before your eyes.

But, how can you tell if your sunflower is dying? Well, notably, the leaves will start yellowing. This discoloration is due to overwatering, nitrogen deficiency, or even an aging plant.

Also, you will notice stunted growth. The new leaves will appear abnormal and stop growing abruptly. Shortly after, the plant will shed the leaves and even turn brown or black based on the issue.

The water problem is also a reason for your sunflowers wilting or developing root rot. Sadly, the problem is usually too late to rescue with overwatering and underwatering as the damage is already in place.

All you need to know is the proper sunflower care to avoid it from dying in the first place.

Does My Sunflower Need Winter Protection?

Because they love the sun, sunflowers hate the cold, especially winter cold. At this time, it would be best to take the plants indoors if you have them in containers.

If you have your sunflowers planted in the ground, you could mulch around the base to insulate the roots. Preferably, dry leaves are great mulch on the soil. While this might seem light action, your sunflowers will appreciate that extra care and protection to help them endure past winter.


Now that you know why your sunflower is closing up, take the necessary step to save it before it’s too late. Besides, it’s too hard to live without the yellow blooms around as a fan of sunflowers. , ensure the growing requirements, though simple, are correctly in place.

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