Lemon Tree Leaves Curling: Causes, Diagnosis, and How to Fix It

There is a particular kind of worry that comes with watching a lemon tree decline. These trees are not just plants to most people — they represent something. A patio project carefully tended. A kitchen garden with real ambition. A tree passed down from a family member who knew how to grow things. When the leaves start curling, something is clearly wrong, and the urgency to fix it feels genuine.

The good news is that curling leaves on a lemon tree are almost always treatable once the underlying cause is identified. The less straightforward news is that several different problems can produce nearly identical symptoms. 

Understanding what to look for — and what questions to ask about your tree’s environment and care — is how you arrive at the right answer. This guide covers every common cause of lemon tree leaf curl, how to distinguish between them, and what to do in each case.

Why Lemon Tree Leaves Curl: The Core Principle

Leaf curling in lemon trees — and in citrus trees generally — is almost always a protective or stress response. When a lemon tree is under pressure, whether from water imbalance, temperature extremes, pests, disease, or nutritional deficiency, the leaves curl inward as a way of reducing surface area. Less surface area exposed to the air means less moisture lost through transpiration. It is, in essence, the tree trying to conserve what it has.

The direction and pattern of the curl, the part of the tree affected, the condition of the rest of the leaf, and the broader context of the tree’s environment all provide clues about the specific cause. Diagnosis is a process of observation — and it is worth taking time with it before reaching for any treatment.

Cause 1: Water Stress — The Most Common Culprit

Water imbalance is responsible for the majority of lemon tree leaf curl cases. Both underwatering and overwatering cause leaves to curl, which is one of the reasons diagnosis requires more than a quick look at the leaves themselves.

Underwatering

When a lemon tree is not receiving enough water, its leaves curl inward — rolling along their length into a narrow tube or taco shape — and may also appear slightly limp or drooping. The soil will feel dry several centimetres below the surface. In severe cases, leaves may develop brown, crispy edges before eventually dropping.

Underwatering is particularly common in container-grown lemon trees, which dry out far more quickly than trees planted in the ground. During summer, a potted lemon tree in full sun may need watering every one to two days in hot weather. Missing even a few days can produce visible leaf curl.

What to do

Water deeply and thoroughly. For container trees, water until it flows freely from the drainage hole, then allow the top few centimetres of soil to dry before watering again. For in-ground trees, water deeply and less frequently — encouraging roots to grow downward rather than shallowly. A consistent watering schedule, adjusted for season, is the long-term solution.

Overwatering and Root Rot

Counterintuitively, overwatering produces similar leaf symptoms to underwatering. When roots are sitting in waterlogged soil for extended periods, they begin to rot. Rotting roots cannot take up water effectively, so the tree experiences drought stress even when surrounded by moisture. The leaves curl, yellow, and often drop prematurely.

The key distinction: with overwatering, the soil feels wet or soggy when you push your finger several centimetres below the surface. With underwatering, the soil is dry at that depth. The soil tells the story that the leaves alone cannot.

Root rot caused by the water mould Phytophthora is a significant cause of serious decline in lemon trees, particularly in heavy clay soils and poorly drained containers.

What to do

Allow the soil to dry out before watering again. For container trees, ensure drainage holes are not blocked and that the tree is not sitting in a saucer of standing water. If root rot is advanced, repot the tree into fresh, well-draining soil, trimming away any black, soft, or foul-smelling roots before replanting. Consider amending heavy garden soil with grit or perlite to improve drainage.

Cause 2: Heat Stress and Sun Scorch

Lemon trees are subtropical plants that love warmth — but they have limits. Prolonged exposure to extremely high temperatures, particularly when combined with low humidity or dry winds, causes leaves to curl upward and inward. This is sometimes called heat roll and is a direct response to excessive transpiration loss.

In very hot conditions, the tree loses moisture through its leaves faster than the roots can replace it, even when the soil is adequately moist. Curling reduces the exposed surface area and slows water loss.

Container trees moved suddenly from indoors to a sunny outdoor position are particularly vulnerable. The abrupt change in temperature and light intensity — without time for the tree to acclimatise — can trigger rapid leaf curl, leaf scorch (brown, bleached patches), and significant leaf drop.

What to do

In peak summer heat, move container trees to a position with afternoon shade, or use shade cloth to filter the most intense direct sun. For in-ground trees, mulching the root zone deeply — with 8 to 10 centimetres of organic mulch kept slightly away from the trunk — helps retain soil moisture and moderate root temperature. Avoid transplanting or repotting in peak summer heat.

When moving a tree from indoor to outdoor conditions, do so gradually over one to two weeks — a process called hardening off — to allow acclimatisation.

Cause 3: Cold Damage and Temperature Stress

Cold is the other temperature extreme that causes leaf curl in lemon trees. Lemon trees are not frost-hardy. Most varieties are damaged by temperatures below -2°C (28°F), and many show stress responses — including leaf curling, discolouration, and drop — at temperatures well above freezing, particularly when combined with cold, drying winds.

Cold-curled leaves tend to curl downward and may also appear darker, slightly translucent, or water-soaked before later turning brown. Cold damage often occurs overnight and becomes visible in the morning.

Container trees left outdoors in cold climates during winter are at particular risk. Even brief exposure to temperatures below 5°C (41°F) can stress a lemon tree that has been growing in warm conditions.

What to do

Bring container trees indoors or into a greenhouse before overnight temperatures regularly fall below 5°C (41°F). For in-ground trees in borderline climates, protect the base with a deep mulch layer, wrap the trunk with horticultural fleece, and cover the canopy with frost cloth when a hard frost is forecast. Once cold damage has occurred, wait until spring warmth returns before assessing and pruning any damaged wood.

Cause 4: Pest Infestation

Several common pests cause lemon tree leaf curl through their feeding activity. Understanding which pest is involved requires looking closely at the leaves — both surfaces — and at the growing tips.

Citrus Leafminer (Phyllocnistis citrella)

The citrus leafminer is one of the most common causes of distinctively curled, distorted new growth on lemon trees worldwide. The adult is a tiny moth that lays eggs on young, developing leaves. The larvae then mine through the leaf tissue just below the surface, creating silvery, winding trails visible through the leaf. As the larvae feed and grow, the leaf curls, twists, and contorts — sometimes quite dramatically.

Leafminer damage is almost exclusively on new growth. Older, mature leaves are not typically affected. If you see the characteristic silvery trails inside curled new leaves, citrus leafminer is the likely culprit.

In healthy adult trees, leafminer damage is largely cosmetic and does not significantly impair growth. In young trees and newly established saplings, repeated heavy infestation can slow development. The curled leaves also provide shelter for other pests and pathogens.

What to do

Spinosad-based organic sprays applied to new growth can reduce leafminer damage. Kaolin clay (a fine mineral powder applied to foliage) creates a physical barrier that reduces egg-laying on new leaves. Avoid excessive fertilising that produces a constant flush of soft new growth — which is exactly what leafminers prefer. In most cases, healthy trees manage leafminer pressure without intervention.

Aphids

Aphids — particularly the brown citrus aphid (Toxoptera citricida) and the spirea aphid (Aphis spiraecola) — feed on the soft tissue of new growth, extracting plant sap and causing leaves to curl, pucker, and distort. Infestations are typically found at the growing tips, where the youngest and most tender leaves are clustered.

Look closely at curled new growth: if you find clusters of small, soft-bodied insects — green, black, brown, or yellow depending on species — along with their white shed skins, aphids are present. Ants attending the colony are another giveaway, as ants farm aphids for their honeydew secretions.

What to do

A strong jet of water from a hose dislodges aphids effectively from small trees. Insecticidal soap sprays applied directly to the colony kill aphids on contact without significant harm to beneficial insects. Neem oil spray provides residual protection. Encouraging natural predators — ladybirds, lacewings, parasitic wasps — by reducing chemical use in the surrounding garden is a long-term population management strategy.

Spider Mites

Spider mites (Tetranychus urticae and related species) are tiny arachnids that feed on leaf cell contents, causing stippled, silver-flecked, or bronzed discolouration and, in severe infestations, leaf curling and drop. They thrive in hot, dry conditions — which is why they are a particular problem for indoor lemon trees and for outdoor trees during summer droughts.

Look for very fine webbing on the undersides of leaves and at growing tips. The mites themselves are tiny — barely visible to the naked eye — but appear as small moving dots under a magnifying lens.

What to do

Increase humidity around the plant; spider mites dislike moist conditions. Spray the undersides of leaves thoroughly with water to dislodge mites. Neem oil or horticultural oil sprays applied to leaf undersides are effective treatments. In severe cases, a miticide labelled for citrus may be required.

Cause 5: Nutritional Deficiencies

Lemon trees are relatively hungry plants, and deficiencies in key nutrients can cause a range of symptoms — including leaf curl — alongside other visual signs that help with diagnosis.

Nitrogen Deficiency

Nitrogen deficiency causes older, lower leaves to yellow and eventually drop, while new growth may be small and pale. In chronic deficiency, leaves can curl slightly as the tree fails to produce adequate chlorophyll and cell structure. This is common in trees grown in poor soil or in containers that have not been fertilised for an extended period.

What to do

Apply a balanced citrus-specific fertiliser or one high in nitrogen. Slow-release granular formulas applied in spring and again in midsummer provide sustained nutrition across the growing season.

Magnesium Deficiency

Magnesium deficiency produces characteristic interveinal chlorosis — yellowing between the leaf veins while the veins themselves remain green — typically on older leaves first. Leaves may also curl slightly as cell structure is compromised.

What to do

Apply magnesium sulphate (Epsom salt) as a foliar spray — dissolve 15g per litre of water and apply directly to foliage — or add it to the soil as a drench. This provides a relatively rapid response.

Iron and Zinc Deficiency

Iron and zinc deficiencies both produce interveinal chlorosis on younger, newer growth rather than older leaves. Both are common in alkaline soils, where pH above 7.0 causes these nutrients to become chemically unavailable even when they are present in the soil.

What to do

Test soil pH. If alkaline, lower it gradually by incorporating sulphur or using an acidifying fertiliser. Apply chelated iron or zinc as a foliar spray for a faster response while working on the underlying pH issue.

Cause 6: Disease

Several fungal and bacterial diseases cause leaf curl and distortion in lemon trees, though most disease-related curl is accompanied by additional visible symptoms.

Citrus canker (Xanthomonas citri subsp. citri) produces raised, corky lesions surrounded by yellow halos on leaves, fruit, and stems. Affected leaves may curl and drop. Citrus canker is a bacterial disease that spreads through water splash and wind-driven rain. It is a regulated pest in many countries.

Greasy spot (Mycosphaerella citri) is a fungal disease that causes yellowish-brown blotches on the upper leaf surface and dark, greasy-looking lesions on the underside. Severe infections cause leaf drop. Copper-based fungicide sprays in spring and summer reduce infection.

Phytophthora brown rot affects fruit but can also impact leaf health indirectly through root damage.

If disease is suspected and your tree is not responding to corrective care measures, consult your local agricultural extension office or a certified horticulturist for diagnosis. Some citrus diseases are regulated and reportable in certain regions.

Diagnosis Checklist: Finding the Right Cause

When your lemon tree leaves are curling, work through these questions in order:

Check the soil first. Is it dry? Underwatering. Is it wet or soggy? Overwatering or root rot. Is it adequately moist? The cause lies elsewhere.

Check the timing and pattern. Is the curl affecting only new growth? Likely leafminer or aphids. Is it affecting the whole tree? Likely water stress, temperature issue, or nutritional deficiency. Did it appear suddenly after a weather event? Likely heat or cold stress.

Inspect the leaves closely. Look for insects, webbing, silvery mining trails, spots, lesions, or unusual discolouration. What you find narrows the cause considerably.

Consider recent changes. Was the tree recently moved, repotted, fertilised, or exposed to unusual weather? Recent changes are often directly connected to new symptoms.

General Care Tips for a Healthy Lemon Tree

Prevention is always more effective than treatment. These practices reduce the risk of leaf curl and keep lemon trees resilient.

• Water deeply and consistently, adjusting for season and container versus in-ground. 
• Fertilise regularly during the growing season with a citrus-specific formula. 
• Maintain slightly acidic soil pH between 5.5 and 6.5. 
• Mulch the root zone of in-ground trees. 
• Inspect new growth regularly for early pest activity. 
• Protect from temperature extremes at both ends. 
• Prune to maintain good airflow through the canopy, which reduces fungal disease pressure.

Frequently Asked Questions

Why are only the new leaves on my lemon tree curling? 

New growth curling with silvery winding trails inside the leaves almost always indicates citrus leafminer. Curled new growth with insects present at the tips indicates aphids. Both are common and manageable.

Can lemon tree leaves uncurl once the problem is fixed? 

Leaves that have curled due to water stress often partially or fully uncurl once watering is corrected and the tree stabilises. Leaves damaged by pests, disease, or physical stress tend not to uncurl — they may remain distorted but will still contribute to photosynthesis. New growth emerging after the problem is resolved will be normal.

My lemon tree is indoors — why are the leaves curling? 

Indoor lemon trees most commonly suffer from low humidity, inconsistent watering, insufficient light, or spider mite infestation. Ensure the tree receives at least six hours of bright light daily (supplemented with a grow light if necessary), mist occasionally or use a pebble tray for humidity, and check carefully for spider mites on leaf undersides.

How often should I water a lemon tree in a pot? 

During summer, every one to two days in hot weather. During spring and autumn, every three to five days. During winter, once a week or less, depending on how quickly the soil dries. Always check the soil with your finger before watering rather than following a fixed schedule.

Is leaf curl on a lemon tree contagious to other plants? 

Leaf curl caused by water stress, temperature, or nutritional deficiency is not contagious. Leaf curl caused by pests or certain diseases can spread to nearby plants. If a pest or disease is involved, treat promptly and monitor neighbouring citrus trees closely.

Final Thoughts

Curling leaves on a lemon tree are a signal — not a sentence. In the large majority of cases, the cause is identifiable and the tree is recoverable with the right response. The key is to resist the urge to treat without diagnosing. Applying pesticide to a tree that is simply underwatered does nothing useful. Increasing watering on a tree suffering from root rot makes things worse.

Look at the soil. Look at the leaves — both sides. Think about what has changed recently in the tree’s environment. The answer is almost always there if you take the time to find it.

Lemon trees, when healthy, are generous and rewarding plants. A little attentive care in the right direction goes a long way toward bringing a stressed one back to health — and keeping it there.

References

1. University of California Agriculture and Natural Resources — Citrus: Solving Leaf and Fruit Problems. https://ipm.ucanr.edu/PMG/GARDEN/PLANTS/DISEASES/citruslf.html
   
2. University of Florida IFAS Extension — Citrus Leafminer (Phyllocnistis citrella). https://edis.ifas.ufl.edu/publication/IN155
   
3. Clemson University Cooperative Extension — Citrus Problems: Diseases, Pests, and Nutritional Disorders. https://hgic.clemson.edu/factsheet/citrus-diseases/
   
4. University of Arizona Cooperative Extension — Growing Citrus in the Home Garden. https://extension.arizona.edu/sites/extension.arizona.edu/files/pubs/az1492.pdf
   
5. Texas A&M AgriLife Extension — Home Citrus Production. https://agrilifeextension.tamu.edu/solutions/home-citrus-production/