Natural aging is the primary reason for the yellowing of daffodil leaves (chlorosis).
After daffodils finish blooming, the foliage stays green for several weeks and gradually begins to yellow and wither.
It is crucial to allow this process because, while they are green, the leaves are busy delivering energy to the bulbs for next year’s blooms.
Once this process has finished, you can let the foliage die back completely and remove it.
More on Daffodil Growing and Care here.
What Are Some Other Reasons Daffodil Leaves Turn Yellow?
Yellowing foliage in daffodils has the same reasons for chlorosis as in other plants.
If your daffodil foliage begins turning yellow before or during bloom time or the height of the growing season, you should suspect a problem.
Here are 5 of the leading problem causes of yellowing daffodil leaves:
1. Overwatering and wet soil cause root rot.
This common fungal infection can cause chlorosis in all sorts of plants.
Luckily, prompt action can counter its effects.
If you notice the leaves of your daffodils turning yellow unseasonably, do the following:
- Check for soggy soil.
- Reduce watering and apply a fungicide treatment to the soil.
- If the bulbs are in poor drainage areas, you must move them.
Also, planting bulbs too deeply can cause root rot.
2. Basal rot is also caused by a fungal infection.
This fungus lies dormant in the soil and activates when temperatures above 55° degrees Fahrenheit.
Leaf yellowing is an early indicator of basal rot.
If left untreated, purple/brown discoloration may rise from the bulb, and the fungus will cause the bulb to become desiccated.
Prompt treatment can help prevent the fungus from spreading to other bulbs.
Follow these steps:
- Remove and dispose of any bulbs that show symptoms of basal rot.
- Treat the surrounding soil with a fungicide to further prevent spread.
3. Leaf scorch is another fungal disease that causes the tips of daffodil leaves to turn yellow and then reddish-brown.
If left untreated, the discoloration will spread until whole leaves turn brown, wither, and die.
You are most likely to see leaf scorch in mild, damp weather.
Prompt attention may save the affected plant and those surrounding it.
Here are the following steps to do:
- Trim away affected parts of the leaves with a sharp, sterilized blade.
- If the disease has progressed and affected whole plants, you must dig up and dispose of those bulbs.
- Treat the surrounding soil with a suitable fungicide.
- Rake away any leaves and debris on the soil’s surface surrounding your daffodils. The fungus can live on this debris.
- Dispose of potentially infected vegetation by burning it or putting it in a sealed plastic bag for trash pickup. Don’t compost it.
4. Mosaic viruses (like Narcissus mosaic virus and Narcissus yellow stripe virus) cause yellowing of the stalks and leaves of daffodils.
You can identify these viruses by how the discoloration manifests in the following:
- Streaks
- Stripes
- Spots
Additionally, the virus may cause leaves to grow in a distorted manner.
There is no cure for mosaic viruses. If you believe your daffodils are infected, you must dig up and dispose of all bulbs.
Allow the ground to lie fallow for a year. Then take steps to get pests such as nematodes and aphids under control.
5. Nutrient deficiencies can cause yellowing leaves in all plants.
But it is a less likely problem in daffodils and other plants grown from bulbs that store nutrients.
Because of nutrient deficiencies, very badly neglected, overcrowded daffodils may develop yellowing leaves.
To prevent this, be sure to do the following:
- Provide a dose of fertilizer when you plant your bulbs and each autumn
- Divide your daffodil bulbs at least once every 5 years.