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Doing the investigative work to find out why the leaves on your sunflower are curling won’t take too long. There are only a few reasons and the clues are easy to spot. Even better, most of the issues you may find – watering and so on – can be put right. Read on to restore help to your sunflower and its curling leaves.
Is the sunflower getting the right amount of moisture?
You could be either over-watering your sunflower plant or under-watering it. In addition, the soil may not be draining sufficiently, letting water pool at the base of the plant. Look at the leaves for a clue as to which of these issues is present: if the leaf is curling upwards then it’s trying to retain water and you’re under-watering it or it’s not getting enough of the water you’re giving it; if it curls downwards, then it’s probably getting too much water.
Next, feel the soil around the plant. Is it thick and clumpy or more loose and granular? Loosen the heavy soil to improve the drainage by digging in some organic compost. This also helps the soil retain the right amount of moisture.
A combination of well-drained soil and a regular watering schedule will overcome your watering problem that is curling the leaves.
Are there aphids on the sunflower’s leaves?
Aphids settle on leaves to eat them. In doing so, they start to destroy the structure of the leaves which distorts how the leaves lay. While sunflowers have a strong resistance to these creatures, it’s worth checking just in case they have made their home on your young sunflower plants. Look on the undersides of all the leaves on your plant for very small white, green or black insects. Sticky spots on the leaves are a giveaway that something has been sucking the sap from them.
To remove the aphids, hose down the plant carefully or spray with insecticidal soap.
Do the sunflower leaves also have brown spots?
Curling yellow leaves coupled with brown spots is a significant clue that your plant has a fungal infection. The most common sunflower disease is Verticillium. Leaves that have this disease also tend to become dry and crispy.
Known also as Vert, this disease is caused by a soil-borne fungus so it usually works its way from the roots to the bottom of the stem of the plant and then goes higher to the leaves. If you first notice your leaves curling about the time the sunflower started flowering, it’s a good bet that this is the disease your plant has.
There’s no cure for this disease. If Vert has only got to a few leaves, carefully remove them but throw them away, don’t compost them. If many leaves are infected, it’s best to pull up the entire sunflower plant and get rid of it. Infected plants become stunted and mature early or die before they flower. Either way, your diseased sunflower plant won’t be as beautiful as it should be.
Other sunflower problems?
We write about the most common sunflower growing problems and give solutions to them (where possible). Please take time to read our other articles: