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Why Is My Fern Turning Yellow?

Yellowing of fern leaves is a common problem caused by overwatering, underwatering, lack of nutrients, pests, diseases, or environmental stress.

Ferns are popular houseplants because of their lush green foliage and ease of care. However, it is alarming when you notice your fern's leaves are turning yellow. This article explores why your fern might be turning yellow and provides tips on keeping your fern healthy and thriving.

Signs Your Fern Houseplant Is Sick

Indoor ferns turning yellow is a cause for concern for many plant enthusiasts. Fern plants, such as the Boston fern and asparagus fern, are known for their lush green fronds that can brighten up any room. However, when these fronds start turning yellow and crispy, it is a sign that something is wrong.

Signs that your fern houseplant is sick include:

  • Wilting or drooping leaves

  • Yellowing or browning of leaves

  • Stunted growth

  • Presence of pests or diseases

The Four Most Common Causes Of Yellow Ferns

There are several common reasons indoor ferns turn yellow, but the most common causes include overwatering, underwatering, lack of nutrients, pest infestations, and environmental stress.

1. Overwatering And Underwatering.

Too much water can cause root rot, leading to the yellowing of leaves. On the other hand, underwatering causes dehydration and stress, resulting in yellow or brown leaves.

Ferns prefer consistently moist soil that’s well-draining and you must water Ferns thoroughly, allowing the excess water to escape and prevent waterlogging the root system.

Water ferns on a consistent watering schedule when the top inch of soil is slightly dry to the touch. However, don’t allow the soil to dry out completely. Use pots with generously-sized drainage holes.

Depending on the environment, ferns may require watering once or twice a week. Watering frequency may vary based on factors such as the size of the pot, soil type, and environmental conditions.

Like other houseplants, under- or over-watering ferns is one of the main culprits of yellow leaves. A healthy fern has lush, green leaves.

2. Lack Of Nutrients

Lack of nutrients, particularly nitrogen, causes yellowing of leaves. On the other hand, overfertilization and too much nitrogen can burn the roots and leaves.

Choose a balanced fertilizer specifically formulated for ferns and follow the manufacturer's instructions for application. Typically, you can fertilize ferns once every four to six weeks during the spring-to-fall growing season.

Avoid fertilizing during the winter months when ferns go dormant. You can add perlite or organic matter, like compost or worm castings, to the potting soil to boost its nutrient content. Alternatively, you can always just start again by repotting the fern into fresh, nutrient-rich soil.

3. Pest Infestations

Pest infestations, such as from scale insects, spider mites, or mealybugs, can suck the sap from the leaves and cause yellowing.

To prevent and cure pest infestations in your indoor fern, you can take the following steps:

  1. Move the affected fern away from other plants to prevent the infestation from spreading.

  2. Look for signs of pests, such as webs or sticky residue on the leaves, and identify the type of pest present. 

  3. Use a cotton swab or soft cloth soaked with rubbing alcohol to wipe off visible pests, such as mealybugs or spider mites, from the plant.

  4. Use natural pesticides such as insecticidal soap, neem oil, or a mixture of water and dish soap to treat the infested fern. Follow the manufacturer's instructions for application.

  5. Healthy plants are less susceptible to pests. Ensure the fern gets adequate water, light, and nutrients to boost its overall health and resilience.

  6. Keep an eye on the fern and inspect it regularly to ensure that the infestation is under control.

4. Environmental Stress

Another culprit of yellowing leaves is too much light. While ferns do need bright light to thrive, direct sunlight is harmful and causes the fronds to turn yellow. 

Additionally, not enough light also causes yellowing and stunted new growth. Other environmental stress, such as exposure to extreme temperatures or low humidity, also causes the yellowing of leaves.

Help your fern recover by following these helpful tips:

  • Ferns prefer bright, indirect sunlight and a relatively stable temperature between 60 and 75°F (15 and 24°C). Avoid placing the fern in direct sunlight or near cold drafts, such as near doors or windows.

  • Ferns prefer high humidity levels, around 50 to 60%. You can increase humidity by putting a tray containing water near the plant or using a humidifier.

  • If the fern is exposed to extreme temperatures, move it to a more suitable location. If the air is too dry, use a humidifier or misting the leaves regularly.

  • Keep an eye on the fern and inspect it regularly for signs of stress, such as yellowing or browning of leaves. Adjust the conditions as needed to keep the fern healthy.

Fern leaves near windows with too much direct sun can get scorched.

Frequently Asked Questions

Should I prune the yellow leaves off my fern?

It depends on the severity. In general, if the yellowing is limited to a few leaves and is caused by natural aging or minor damage, simply remove the affected leaves to improve the plant's appearance.

However, if the yellowing is widespread and driven by overwatering, underwatering, or nutrient deficiency, it's important to address the underlying issue first before trimming any leaves.

Additionally, if a pest infestation has caused the yellowing, remove the affected leaves promptly to prevent the pests from spreading to other parts of the plant.

When removing leaves, use clean, sharp scissors or shears and make a clean cut close to the base of the leaf. Avoid tearing or pulling the leaves, as this damages the plant.

Will yellow fern leaves turn green again?

Unfortunately, yellow fern leaves will not turn green again once they turn brown or yellow. Yellowing leaves are a sign that the leaf is dying or has died and no longer produce chlorophyll, which gives leaves their green color.

However, by practicing proper plant care and addressing the underlying issue causing the yellowing, such as overwatering or nutrient deficiency, you can prevent further yellowing and promote the growth of healthy new green leaves.

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