One of the most stunning and lovely plants we may use to decorate our house and garden is the sunflower plant, also known by its scientific name, Helianthus annuus. Yellowing of sunflower leaves is a common issue, and you are in the right place if you wonder why, you can see leaf yellowing on your sunflower.
Sunflowers are easily grown from seed and are abundant in gardens all around the world. However, there are a few challenges, like with other plants. In our guide, you can find out why your sunflower seedlings end up with yellow leaves.
By the end, you’ll have enough information to quickly fix the problems causing yellowing leaves on your sunflowers and possibly on other plants with the same issues.
What Do Sunflower Leaves Look Like?
Most sunflowers feature triangular or heart-shaped leaves. The leaves are divided into discrete portions by a little spine. Dark green in color, the type of sunflower you are cultivating may have some distinct colored foliage.
As the plant grows taller, sunflower leaves enlarge considerably. They grow and give the sunflowers a lovely leafy appearance. Because of their two cotyledons, sunflowers are categorized as dicots. The leaves develop in pairs at a time.
Why Are Sunflowers Leaves Turning Yellow?
Your sunflower is not getting enough nutrition if its leaves turn yellow (or brown). Ensure it receives adequate sunlight, is not overwatered, and has enough space to flourish.
Check for insects that frequent the plant, as they might prevent essential nutrients from reaching the leaves, leading to discoloration. Here, in more detail, are the reasons you can see leaves turning yellow. (Read 8-10-8 Fertilizer For The Banana Tree)
1. Your Sunflower Doesn’t Receive Enough Nutrients
Because of their intense feeding habits and high nutrient consumption, sunflowers can change the color of their leaves if they don’t receive enough of them.
Nitrogen and phosphorus deficiencies are the most common.
A lack of nitrogen is shown by yellow leaves that remain green in the veins of the leaf surface, but yellow leaves show a deficiency of phosphorus with a purple or reddish hue.
Using fertilizer with additional nitrogen or phosphorus can help you resolve this.
2. You Are Using A Small Pot For Your Sunflower
If you’re growing your sunflower in a pot, ensure the container has enough room for the plant’s root zone to spread out, or it will become root bound. If you’re going to use a pot, seek one at least five-gallon size to ensure that the plant gets adequate soil and nutrients from its deep roots.
To avoid flooding the plant when you water it, you should also ensure the pot has adequate drainage. When growing sunflowers, if you want to repot your sunflower as you do with most plants, do so carefully, quickly, and without disturbing the roots.
After you have repotted it, water it, and then wait until the top is completely dry before watering it again.
3. Your Sunflower Has Too Much Water
If the leaves on your sunflower are starting to turn yellow, these are early signs you have a watering problem, and most often, it is overwatering, or your pot doesn’t drain well enough.
Sunflowers require a significant amount of water during the germination stage. Once they grow, however, 1 to 1.5 inches each week should be adequate for a healthy plant.
While sunflowers require a steady water supply, too much water might cause them to get soggy. Water your sunflower or sunflowers until the top six inches of soil are moist. Then, water once more when the topsoil has dried.
4. Your Sunflower Has A Lack Of Sunlight
Anyone who loves sunflowers will know sunflowers love lots of sun and need at least six to eight hours of unfiltered sunlight per day. However, it might be because it’s dehydrated when you plant sunflowers and wonder why your sunflower’s leaves are turning brown.
A sunflower may wilt if exposed to high temperatures higher than 32 or 33 degrees Celsius for an extended period.
5. Your Plant Could Suffer from Fungal Rot
Fungal rots can harm sunflowers’ base, stem, and crown and cause brown or yellow, wilting leaves or ones that appears dull. Fungi in the soil damages the plant, rising upwards. The first sign of a fungal infection is brown spots on the leaves and stem, or any other symptoms are foliage that yellows without warning.
You may assume your sunflower isn’t getting enough water, but fungus is probably to blame if it’s wilting after being watered and has brown spots on its leaves. Sunflowers can pass this fungal infection to other plants, so remove them and discard them properly.
If you wish to plant sunflowers again, avoid the previously affected soil.
To treat this, remove any seriously afflicted leaves and spray the other leaves with a mixture of baking soda, liquid detergent, vegetable oil, and water.
6. Plants May Have Sunflower Rust
Sunflower rust causes leaves to become reddish-brown and develop yellow halos. Puccinia Helianthi causes this. It needs water on the leaves to flourish; thus, watering the plant’s base can lessen this risk.
Untreated sunflower rust can destroy your sunflower, but early treatment should cause damage. Burn or bag infected leaves to dispose of them.
7. Insect Issues
Unfortunately, a lot of pests love sunflowers as much as you do. Many of these feed on the plant’s sap and starve the leaves for nourishment, causing them to turn yellow or brown.
Beetles: In the spring and summer, target young plants, and every single leaf can be affected. Aphids gather in groups on the underside of leaves and suck the juice.
What does a sunflower leaf look like after Spider mites have invaded? These insects create tiny webs on the plant that give it a white complexion. An organic insecticide, neem oil, or horticultural oil is the best way to deal with these. (Learn How To Get Rid Of Mushroom In Mulch)
8. Is Nature Doing Its Job?
If all the other signs are not why you have yellowing leaves, then you could find that nature has a hand in this. This is normal if the leaves at the bottom of the plant are turning yellow or brown.
It shows these leaves have completed their task of establishing the plant and are being shed by the sunflower so it may concentrate on developing flowers. In this situation, there is nothing you need to do; they will pass away naturally.
What’s Wrong with My Sunflower Plant?
1: Droopy Leaves:
Usually, a sunflower’s wilting leaves show that plant is thirsty. Weirdly, wilting may also be a sign of excess water. For the best outcomes, try to keep track of your watering and rainfall.
2: Yellow Leaves:
You can see your sunflowers leaves turning yellow if it receives too much water from rain or watering or if there is poor drainage. Yellow leaves or the flower head may also show a lack of nitrogen.
3: Curling Leaves:
Verticillium infection can cause the appearance of leaves to become spotted with yellow, green, and crispy brown spots.
4: Holes In Leaves:
Keep an eye out for pests that might harm sunflower seeds, particularly caterpillars, which store or eat.
5: Missing Leaves:
It’s possible that a larger animal, such as a deer, groundhog, or rabbit, is creeping through your yard and nibbling on your plants.
Keep your sunflower in the ground if it was bitten above the cotyledon. Soon, see two fresh shoots emerging, one on each side. Even when the sunflowers may become smaller, all is not lost!
Several animal types can eat sunflower seeds falling from the flower head.
6: Crispy Brown Leaves:
This is the last predicted behavior of the leaves if the sunflower seed head has been left on the plant so that seeds can mature.
Sunflower Leaves Yellowing – Why Are Sunflowers Turning Yellow
Now that we’ve covered the sunflower plant’s life cycle, we can get to the meat of our inquiry. The sunflower leaves turning yellow can leave many gardeners baffled. Causes and solutions for yellowing sunflower leaves are here.
How to Fix Sunflower Leaves Yellowing Because of Nutrient Deficiencies
Although sunflower uses significantly more potassium (K) proportionally, this will return to the soil if the crop leftovers are integrated into it, as the sunflower plant has a great capacity to drain soil nutrients, especially phosphorus (P) and nitrogen (N).
Fertilization is crucial to the plant’s growth; thus, we must pay close attention to both the flowering and seed maturation stages, mainly if the oil is extracted from the seeds.
As we’ve already established, nutritional deficiencies, notably phosphorus, nitrogen, and potassium, are a leading cause of foliage yellowing of sunflower leaves and fewer blooms, among other factors.
Sunflower Leaves Turning Yellow Because of Overwatering
Sunflowers can turn their leaves yellow if they get too much moisture. Because fungi thrive in damp environments, the leaves of sunflowers will turn yellow if they are overwatered.
However, if you overwater your sunflowers, the roots will rot, and the plant will decay, which will cause the leaves to turn yellow.
Sunflower Leaves Turning Yellow Because of Excess Heat
The excessive heat is causing the leaves of the sunflower to turn yellow. Sunflowers love warm temperatures, yet their leaves turn yellow when they soar for extended periods, and the plant’s health suffers.
Sunflowers thrive on warm days with plenty of sunshine; if exposed to extreme heat for extended weather, the sunflower may perish. When sunflowers have been exposed to high temperatures for several days during the growing season, they must receive adequate irrigation.
Sunflowers should ideally be watered very early in the morning or late in the evening when the sun’s intensity has decreased. Remember that you should not end up over watering sunflowers either; if you do, mold may form because of the excess humidity, the roots of the sunflowers may rot, and all the leaves may turn yellow. (Read Will Roundup Kill Pine Trees)
Sunflower Leaves Yellowing because of Pest and Diseases
Because of diseases and pests, sunflower leaves are turning yellow. As we’ve already mentioned, excessive irrigation can cause fungus to grow on sunflowers. Additionally, pests like aphids and spider mites harm sunflowers.
Our sunflower’s sap is consumed by aphids, mites, and spider mites, which deplete the plant of nutrients and cause the sunflower to develop yellow leaves.
Is the sunflower getting the proper nutrients?
The plant may suffer from not receiving nutrients or the wrong amount or type of nutrients. Even though sunflowers often do not require fertilizer, soil with inadequate integral nutrients should be supplemented with the proper nutrients and fertilizer to allow for the firm and healthy growth of the sunflower.
Nitrogen is the most crucial ingredient for sunflowers. The stem becomes weakened, the leaves turn yellow, and the plant begins to die from a nitrogen deficiency.
The fertilizer for these plants is water soluble all-purpose plant food, yet you can find beautiful results using tomato feed. However, be cautious, as too much nitrogen in the soil causes the sunflower to produce more leaves than blossoms.
As you can see, there are several reasons your sunflower plant’s leaves can turn yellow. The most crucial thing to remember is that, in most situations, there is a way to address the issue and promote healthy growth once the plant starts turning and you know the cause of the issue.
The worst cases, such as severe fungal rot, can be fatal for your flowers, and you might have to move on and get rid of them. Sunflowers are low-maintenance, easy-to-grow plants that may be grown in various conditions.
They will fill your yard with a ton of color and are ideal for beginning gardeners.