Lemon trees with their bright, sunny fruit and fragrant blossoms are a delightful addition to any garden. But if your lemon tree’s leaves start turning yellow, it can quickly turn into an eyesore. Yellowing leaves are a sign that your lemon tree is stressed and unhealthy. Don’t fret — with some detective work and attentive care, you can get your tree back to its vibrant glory. Here is a comprehensive guide to diagnosing and treating yellow leaves on your lemon tree.

Reasons Why Lemon Tree Leaves Turn Yellow

Before you can fix the problem, you need to understand why your lemon tree leaves are yellowing in the first place. There are several common reasons this can happen:

Improper Watering

Too much or too little water is the most common cause of yellow lemon foliage. Lemons are native to warm climates and require consistent moisture. If you underwater your lemon tree, the leaves will start to droop and turn yellow. Overwatering can also lead to root rot and nutrient deficiencies that cause yellowing. Stick to deep weekly soakings during spring and summer, reducing frequency in fall and winter.

Poor Drainage

Lemons hate wet feet. If the soil takes more than a few days to dry out after watering, it likely has poor drainage. This leads to root rot and yellowing leaves. Improve drainage by amending clay soils with compost or planting the tree in a raised bed.

Nutrient Deficiencies

Lack of essential nutrients like nitrogen, iron, zinc, and manganese can cause lemon tree leaves to yellow and drop. This is common in alkaline soils. Test the soil pH and amend it to a level between 6.0-6.5. Fertilize trees monthly during the growing season with a citrus fertilizer.

Cold Weather

Lemons are incredibly sensitive to cold temperatures. If temps dip below 45°F, leaves may start turning yellow. Protect trees from frost and freezing to prevent leaf drop. Move potted trees indoors or cover in-ground trees during cold snaps.

Pests

Insects like aphids, mealybugs, mites, and scales can all infest lemon trees and cause leaf yellowing and drop. Check trees frequently for signs of an infestation and use horticultural oils or insecticidal soaps to treat pests.

Diseases

Fungal diseases like anthracnose, root rot, and citrus greening disease can also lead to yellowing lemon foliage. Use preventative fungicide sprays and prune off affected branches to manage diseases. Remove and destroy any infected trees.

Age

As lemon trees mature over time, a natural loss of interior leaves and yellowing is common. This is not necessarily a cause for concern in older trees as long as new growth looks healthy. Focus on keeping the tree vigorous.

How to Fix and Prevent Yellow Leaves on a Lemon Tree

Once you’ve diagnosed the cause of the yellowing leaves, it’s time to take action to restore your lemon tree’s health. Here are solutions for the most common issues leading to yellow leaves:

Adjust Watering

Carefully monitor soil moisture and only water when the top few inches become dry. Stick your finger in the soil to check – don’t just water on a schedule. Deeply soak the entire root zone until water drains from the bottom of the container or from weep holes at the base of in-ground trees. Allow the soil to partially dry out between waterings.

Add organic mulch like wood chips around in-ground trees to retain soil moisture. For potted trees, make sure there is drainage hole(s) and use free-draining soilless potting mix. Move containers out of hot midday sun to slow soil drying.

Yellowing due to overwatering requires cutting back on frequency. Let the soil dry further between waterings. For underwatered trees, begin a consistent weekly watering regimen. Leach out mineral buildup monthly by heavily watering until excess drains from the bottom.

Improve Drainage

Plant lemon trees in sandy loam or loamy soil enriched with compost. Amend dense clay soils by mixing in organic material like compost, peat moss, or well-rotted manure.

Create raised planting beds for in-ground trees to improve drainage. Make sure any container has holes for drainage. Place a layer of gravel, Styrofoam, or other coarse material in the bottom of pots below the soil to facilitate drainage.

If you suspect root rot, scrape away an inch of soil from the surface beneath the tree’s drip line. If roots are brown or foul-smelling, you likely have a drainage issue.

Test and Amend Soil

Use a home soil testing kit to determine the pH of the soil. Lemon trees thrive best with a pH between 6.0-6.5. If pH is too high, amend the soil with elemental sulfur or aluminum sulfate.

Re-test the soil yearly and fertilize as needed to maintain nutrients within optimal ranges. Choose a fertilizer specifically formulated for citrus. Apply in early spring after the final frost and again midsummer.

You can also do regular foliar feedings by spraying the leaves monthly with liquid kelp or fish emulsion to provide micronutrients.

Protect from Cold

Move potted lemon trees indoors or under protective overhangs when temperatures drop below 45°F. If left outdoors, wrap the container with insulation.

For in-ground trees, bank soil or mulch around the base to insulate roots from cold penetrations. Cover the tree with frost cloth or burlap if hard freezes are expected. String outdoor holiday lights on branches to generate a little heat.

When yellowing is due to cold damage, prune back affected branches and wait for new growth in spring. Keep trees dormant in winter by cutting back on water and fertilizer.

Treat Pests

Check lemon trees routinely for signs of infestation like sticky honeydew residue or tiny insects on the undersides of leaves. Targeted spraying of insecticidal soap or neem oil every 1-2 weeks will control most soft-bodied pests.

For scale, use a soft brush or cotton swab dipped in alcohol to manually remove the bumps. Trim off heavily infested branches. Apply horticultural oil for moderate infestations.

introduce beneficial insects like ladybugs, lacewings, and parasitic wasps that naturally control pests. Hang yellow sticky traps in trees to monitor and trap flying insects.

Remove any weeds, debris, or diseased branches around the tree that can harbor pests. Keep the area under the tree canopy clean.

Prevent Diseases

Disinfect pruning tools with bleach between each cut. Sterilize saws before trimming diseased branches. Clean up and dispose of fallen leaves and fruits.

Use preventative fungicidal sprays containing chlorothalonil, myclobutanil, or copper early in the season before disease onset. Improve air circulation and light penetration with proper pruning.

Immediately remove any branches or whole trees showing signs of fungal infection like cankers, rot, wilt, or blight. Never compost diseased plant material.

Prune for Tree Health

Do light annual pruning in late winter to shape trees, remove deadwood, and encourage new growth. Never remove more than 20% of the canopy at once. Sterilize pruning tools after each cut.

Thin out inner branches and leaves to allow sunlight, air circulation, and proper lemon bud development. Keep the center of the canopy open on mature trees.

Remove water sprouts and dense vertical branches. Cut back leggy growth and inward facing branches rubbing on the trunk.

Troubleshooting Specific Nutrient Deficiencies

Nutrient deficiencies usually cause distinct patterns of yellowing on lemon tree leaves. Learn how to identify and correct common deficiencies:

Nitrogen Deficiency

Symptoms: Uniform pale green or yellowing of older leaves first while veins stay green. Stunted growth.

Treatment: Fertilize with a nitrogen-rich citrus fertilizer. Apply compost tea or fish emulsion. Ensure adequate irrigation since nitrogen uptake requires water.

Iron Deficiency

Symptoms: Interveinal yellowing on newest leaves while veins remain dark green. Leaf margins brown and curl upward.

Treatment: Spray leaves with iron chelate supplements or iron sulfate. Maintain soil pH 6.0-6.5 since iron is unavailable at higher (alkaline) pH.

Zinc Deficiency

Symptoms: Broad golden yellow bands inside leaf margins, leaving a dark green V shape in the center along the midrib. Sometimes curling.

Treatment: Spray leaves with zinc sulfate. Mix zinc into alkaline soils. Ensure adequate manganese.

Manganese Deficiency

Symptoms: Pale green older leaves with dark green fine veins. Dead spots and brown necrotic patches on leaves.

Treatment: Apply manganese chelate spray. Lower soil pH below 6.5 to increase manganese availability.

Frequently Asked Questions About Lemon Trees with Yellow Leaves

1. Why are the leaves on my lemon tree turning yellow and falling off?

Yellow, dropping leaves are typically caused by improper watering, poor drainage, nutrient deficiencies, pests, diseases, or cold damage. Overwatering and underwatering are two of the most common causes of lemon leaf yellowing.

2. How can I tell if my lemon tree is overwatered or underwatered?

Check the soil moisture before watering – overwatered soil will be soggy, while under-watered soil will be dry 2-3 inches deep. Drooping yellow leaves often indicate under-watering, while leaf drop and root rot occur with overwatering.

3. What should I do if my lemon tree has yellow leaves from too much water?

Allow the soil to dry further between waterings. Remove the tree from soggy soil, prune off rotten roots, and replant in well-draining soil. Apply compost tea to regenerate healthy root growth.

4. How often should you water a lemon tree?

Lemon trees need deep weekly watering in summer when top few inches of soil become dry. Water 1-2 times monthly in cooler weather. Soil should dry out partially between waterings.

5. Can yellow leaves be caused by nutrients deficiency?

Yes, lack of key nutrients like nitrogen, iron, zinc, and manganese commonly causes distinct yellowing patterns on lemon foliage. Have soil tested and fertilize as needed.

6. What fertilizer is best for a lemon tree?

Use a balanced citrus fertilizer with micronutrients. Apply in early spring, midsummer, and optionally during a lighter dormant winter feeding. Avoid high-nitrogen fertilizers.

7. How can I treat lemon leaf curl?

Leaf curl can be caused by pests, diseases, or environmental stress. Improve growing conditions and spray neem oil. Severe curling may require treatment with fungicides.

8. Is lemon tree yellow leaf drop normal?

Some yellowing and leaf drop is normal on inner canopy branches as trees age or enter dormancy. But excessive leaf loss indicates a water, nutrient, disease, or pest problem.

9. Can yellow leaves recover or do they need to be removed?
   Leaves that have turned completely yellow and fallen off won’t recover. But leaves with partial yellowing may re-green after you correct the underlying issue. Remove only fully yellowed leaves.
10. How do I winterize my lemon tree?
    Lemon care in winter focuses on protecting from frost and avoiding overwatering. Move potted trees indoors above 45°F. Prune lightly, fertilize sparingly, reduce water, and allow dormancy until spring growth resumes.

Conclusion

While lemon tree leaf yellowing can be discouraging, identifying the trigger and making appropriate cultural changes can restore vigor. Monitor soil moisture, drainage, nutrients, and pest pressure. Protect trees from cold damage. With attentive care and good growing conditions, you can keep those lemon tree leaves lush and green.

Summary

• Yellow leaves on a lemon tree are typically caused by improper watering, poor drainage, nutrient deficiencies, cold weather, pests, diseases, or age-related leaf drop.
• To fix the issue, adjust your watering habits, amend soil, control pests, protect from frost, prune judiciously, and fertilize as needed.
• Test and maintain optimal soil pH and nutrient levels. Provide adequate irrigation, drainage, sunlight, and ventilation.
• Address yellow foliage right away to prevent leaf loss and reverse decline. With attentive troubleshooting and care, you can nurse your lemon tree back to health.