Citrus trees are a beautiful and rewarding addition to any garden, providing fragrant blossoms and delicious fruit. However, if you notice your tree’s leaves turning yellow or dropping prematurely, it can be concerning. These symptoms can indicate a range of issues, from nutrient deficiencies to environmental stress. The good news? With the right diagnosis and care, you can restore your citrus tree to full health.
Understanding Why Citrus Leaves Turn Yellow
Yellowing leaves, also known as chlorosis, are a sign that your citrus tree is struggling. The key to fixing the problem is understanding what’s causing it. Here are some common reasons citrus tree leaves turn yellow:
1. Nutrient Deficiencies
Citrus trees require a balanced supply of essential nutrients. If one or more are missing, yellow leaves can develop. Here’s how to recognize specific deficiencies:
- Nitrogen Deficiency
- Symptoms: Older leaves turn pale green to yellow, while new growth remains green.
- Cause: Lack of nitrogen due to poor soil quality or leaching from excessive watering.
- Solution: Apply a balanced citrus fertilizer with higher nitrogen content. Slow-release fertilizers or composted manure can also help.
- Iron Deficiency (Interveinal Chlorosis)
- Symptoms: Leaves turn yellow while veins remain green, often affecting younger leaves first.
- Cause: Alkaline soil (high pH) that binds iron, making it unavailable to the tree.
- Solution: Apply iron chelates or soil acidifiers like sulfur to lower soil pH.
- Magnesium Deficiency
- Symptoms: Yellowing starts at the leaf edges, leaving a green center (also called “green island” effect). It usually affects older leaves first.
- Cause: Lack of magnesium, often due to nutrient imbalance.
- Solution: Use Epsom salt (magnesium sulfate) as a soil drench or foliar spray.
- Zinc Deficiency
- Symptoms: Small yellow spots appear on leaves, and leaf size may be reduced.
- Cause: Insufficient zinc in the soil or competition with other nutrients.
- Solution: Apply a foliar spray with zinc sulfate to correct the deficiency.
2. Overwatering or Poor Drainage
Citrus trees do not tolerate soggy roots. Waterlogged soil suffocates the roots, reducing oxygen availability and leading to yellowing leaves.
- Signs of Overwatering:
- Leaves yellowing from the bottom up
- Mushy, darkened roots (root rot)
- A musty, rotten smell from the soil
- Solution:
- Improve drainage by using well-draining soil.
- Water only when the top 2–3 inches of soil feel dry.
- If growing in a pot, ensure it has drainage holes.
3. Underwatering
Just like too much water, too little water can also cause yellowing leaves.
- Signs of Underwatering:
- Leaves turn yellow and become dry or crispy.
- Curling or drooping leaves.
- Soil is extremely dry and pulling away from the pot edges.
- Solution:
- Deep-water the tree thoroughly and consistently, especially in dry or hot weather.
- Apply a 2- to 3-inch layer of mulch around the base to retain moisture, but avoid direct contact with the trunk.
4. Temperature Stress
Citrus trees thrive in warm climates. Extreme temperatures—both hot and cold—can stress the tree and lead to yellowing leaves.
- Cold Stress (Below 50°F / 10°C):
- Leaves may yellow and drop if exposed to frost.
- More common in potted citrus left outside during winter.
- Heat Stress (Above 90°F / 32°C):
- Leaves may wilt, turn yellow, and fall off.
- Prolonged exposure can cause sunscald on leaves and fruit.
- Solution:
- For Cold Weather: Cover trees with frost cloths or bring potted citrus indoors.
- For Hot Weather: Provide shade during peak heat and increase watering slightly.
5. Pests and Diseases
Pests and fungal infections can weaken citrus trees, leading to yellowing leaves and other symptoms.
Common Citrus Pests
- Aphids
- Symptoms: Small, soft-bodied insects on new growth, causing curled and yellowing leaves.
- Solution: Spray with insecticidal soap or neem oil.
- Spider Mites
- Symptoms: Tiny, almost invisible mites cause speckled yellowing and fine webbing on leaves.
- Solution: Rinse leaves with water and use neem oil or miticides.
- Scale Insects
- Symptoms: Hard, shell-like bumps on leaves and stems, leading to yellowing and sticky leaves (honeydew secretion).
- Solution: Remove scales manually or apply horticultural oil.
Common Citrus Diseases
- Root Rot (Phytophthora)
- Symptoms: Yellow leaves, wilting, and slow growth due to overwatering.
- Solution: Improve drainage and avoid excessive watering. Use a fungicide if necessary.
- Greasy Spot Fungus
- Symptoms: Yellow-brown spots on leaves that eventually turn black.
- Solution: Prune infected leaves and apply a copper-based fungicide.
- Citrus Canker
- Symptoms: Yellow lesions on leaves with brown, corky edges.
- Solution: Remove infected leaves and disinfect pruning tools to prevent spread.
How to Prevent and Treat Citrus Leaf Yellowing & Drop
Once you’ve identified the cause, it’s time to take action. Follow these steps to restore your citrus tree’s health and prevent further damage.
1. Adjust Watering Habits
Watering mistakes—whether too much or too little—are a leading cause of yellowing leaves in citrus trees. Finding the right balance is key.
Proper Watering Techniques
- Deep, Infrequent Watering: Water the tree thoroughly but less frequently to encourage deep root growth.
- Check Soil Moisture: Before watering, insert your finger or a moisture meter 2-3 inches into the soil. If it feels dry, it’s time to water.
- Morning Watering: Water early in the day to reduce evaporation and allow the tree to absorb moisture before the heat sets in.
Improving Drainage
- For Potted Citrus Trees: Ensure your pot has drainage holes, and use a well-draining mix containing perlite or sand.
- For In-Ground Citrus Trees: If your soil has poor drainage, plant your tree in a raised bed or amend the soil with organic matter to improve aeration.
✅ Tip: If you suspect overwatering, hold off on watering for a few days and allow the soil to dry before resuming a proper watering schedule.
2. Feed Your Citrus Tree Properly
Citrus trees require a balanced diet of nutrients to stay healthy, produce fruit, and maintain green leaves. A deficiency in key nutrients can lead to yellowing and leaf drop.
Choosing the Right Fertilizer
Look for a citrus-specific fertilizer that contains:
- Nitrogen (N) – Essential for leafy green growth and overall tree vigor.
- Phosphorus (P) – Supports strong root development.
- Potassium (K) – Helps with fruit production, disease resistance, and overall health.
- Micronutrients: Ensure the fertilizer includes iron, magnesium, and zinc, as deficiencies can cause leaf yellowing.
Fertilizing Schedule
- Spring & Summer (Active Growth Season): Feed every 4-6 weeks.
- Fall & Winter (Dormant Season): Reduce feeding to prevent excess growth when the tree’s energy is focused on survival.
✅ Tip: Apply fertilizer around the drip line (outer edges of the canopy) rather than near the trunk to encourage root uptake.
3. Protect Against Extreme Weather
Citrus trees are sensitive to temperature fluctuations. Both cold snaps and extreme heat can stress the tree, causing yellowing and leaf drop.
Cold Protection
- If frost is expected, cover your tree with frost cloths, burlap, or old blankets overnight.
- For potted citrus trees, bring them indoors or into a greenhouse during cold weather.
- Apply mulch around the base of in-ground trees to insulate roots from temperature fluctuations.
Heat Protection
- Provide Afternoon Shade: If temperatures exceed 90°F (32°C), place shade cloth or use nearby structures to protect the tree from direct sun.
- Increase Watering: Water deeply during heat waves to prevent dehydration.
✅ Tip: Avoid fertilizing during extreme heat or cold—this can put unnecessary stress on the tree.
4. Keep Pests and Diseases in Check
Pests and fungal infections weaken citrus trees, making them more susceptible to leaf yellowing and drop.
Pest Control
- Inspect leaves regularly, especially the undersides, where pests like aphids and spider mites tend to hide.
- Common Citrus Pests to Watch For:
- Aphids – Cause curling and yellowing of new leaves.
- Scale Insects – Appear as tiny bumps on leaves/stems and secrete sticky honeydew.
- Spider Mites – Cause speckled yellowing and fine webbing on leaves.
- Solutions:
- Use insecticidal soap or neem oil to control pests.
- For severe infestations, introduce beneficial insects like ladybugs.
Disease Prevention
- Root Rot (Phytophthora): Often caused by overwatering—ensure proper drainage.
- Greasy Spot Fungus: Appears as yellow-brown spots—treat with a copper-based fungicide.
- Citrus Canker: Causes yellow lesions—prune affected areas and disinfect tools.
✅ Tip: Keep the area around the tree clean and free of fallen leaves to reduce disease risk.
5. Prune Your Tree Correctly
Pruning helps remove dead or diseased leaves, allowing for new healthy growth. However, excessive pruning can stress the tree.
When & How to Prune
- Best Time: Late winter to early spring before new growth starts.
- Remove:
- Dead, diseased, or yellowing leaves.
- Overlapping branches to improve air circulation.
- Suckers (small shoots from the tree base) to direct energy toward fruiting branches.
✅ Tip: Always use sharp, sterilized pruning shears to prevent spreading diseases.
6. Repot Potted Citrus Trees When Necessary
If your potted citrus tree is developing yellow leaves, it may be root-bound—meaning the roots have outgrown the pot.
Signs Your Citrus Needs Repotting
- Roots are growing out of the drainage holes.
- Water drains too quickly, leaving the soil dry.
- The tree appears stunted, with fewer new leaves.
How to Repot Correctly
- Choose a pot 2-3 inches larger in diameter than the current one.
- Use fresh, well-draining potting mix designed for citrus.
- Gently loosen the root ball and trim any circling roots before replanting.
- Water thoroughly after repotting and place in a partially shaded area for a few days to minimize transplant shock.
✅ Tip: Repot every 2-3 years to prevent root binding and replenish soil nutrients.
When to Worry: Signs of a Serious Problem
If your citrus tree continues to decline despite your efforts, look for these warning signs that indicate a more serious issue:
- Rapid Leaf Drop: If your tree loses a large number of leaves in a short time, it may be experiencing severe stress.
- Wilting Along With Yellowing: This could indicate root rot or a pest infestation.
- Brown or Black Spots on Leaves: Could be a sign of fungal disease that requires treatment.
- Cracked or Peeling Bark: Indicates severe dehydration or disease.
If you notice these symptoms, act quickly by adjusting care routines, applying treatments, or consulting a local horticulturist for advice.
Final Thoughts
A citrus tree with yellowing leaves or excessive leaf drop may seem alarming, but in most cases, the issue can be resolved with proper care. The key is to diagnose the problem early and take the necessary steps to correct it. By providing the right balance of nutrients, water, and protection from environmental stressors, your citrus tree will thrive and reward you with lush green leaves and delicious fruit for years to come.
Take the time to monitor your tree, make adjustments as needed, and enjoy the beauty and bounty of healthy citrus trees in your garden!