Lemon tree leaves curl up as a reaction to drought. Excess wind, low humidity, watering too lightly all sap moisture from the leaves causing them to curl to conserve moisture. Aphid infestations feed on the sap of emerging leaves which causes leaves to curl.
Whilst drought stress is the most common reason for leaves curling on your lemon tree, nutrient deficient soil, transplant shock from moving lemon trees indoors and even over watering can cause leaves to curl often with yellowing of leaves and leaf drop.
Keep reading to identify the causes curling leaves, how to prevent it and how to revive your lemon tree…
Under Watering is the Most Common Cause of Curling Leaves
Leaves that have a shriveled and curled appearance most often indicate that the lemon tree is suffering from drought stress.
Lemon trees actually prefer the soil to be on the dryer side compared to a lot of fruit trees but problems occur when the soil dries out completely or there is too much wind that saps moisture from the leaves.
Lemon tree leaves curl because:
- Watering too lightly. Lemon trees prefer the top two inches of the soil to dry out between bouts of watering, followed by a generous soak, around once per week. If the lemon tree is watered too lightly the water does not infiltrate the soil and reach the roots which causes the leaves to curl.
- Pots heat dry out quicker. The soil in pots dries out a lot quicker then the soil in garden boarders. Pots have less capacity for soil and therefore less capacity for moisture. Also lemon trees require full sun which can further exacerbate the drying of pots and cause drought.
- Excess wind. Lemon trees should have some protection from wind as excess wind increases moisture loss from the leaves which is one of the more rapid causes of the leaves curling.
Revive Lemon Trees with Curling Leaves due to Drought
Lemon Trees with curling leaves that have suffered drought can be revived if you adjust some conditions.
- Try to shelter the tree from direct wind. With potted trees this may be as simple as moving the dry to an area with a natural wind break such as shelter from other trees or fences. Be careful not to deprive you lemon tree of sunlight when moving it to more shelter. For lemon trees planted in garden soil try to form a wind break with other plants to buffer the worst of the winds.
- Mist the lemon trees shriveled leaves with a sprayer to increase the humidity of the micro-climate to mitigate water loss from the leaves. Spray the leaves twice a day whilst the lemon tree recovers.
- Use a soaker hose for lemon trees planted in the garden. Leave the soaker hose on for several hours to saturate the ground. It is important to be generous with watering after drought because excess heat and sun bake the soil hard so that water runs off the surface rather then infiltrating to the roots, so ensure that you give the tree a generous soak.
- Increase the frequency of watering for lemon trees in pots. Potted plants dry out quicker, particularly in full sun. Lemon trees prefer the soil to be somewhat dry between bouts of watering but too much sun and heat can cause drought stress. Water as soon as the top two inches of the soil are dry which can be twice a week or more in summer.
For potted lemon trees suffering from drought it can be beneficial to submerge the entire pot in water if possible either in a basin or wheel barrow of water.
Submerging the pot in water allows the moisture to reach the roots without running off the surface of the dry soil and down the side of the pot without reaching the roots.
Once the lemon tree has a good watering and the leaves have been sprayed regularly, the leaves should recover from their curled appearance over the following week.
If it is a hot day I recommend temporarily shading the lemon tree, so that it does not have to contend with blazing sunshine whilst recovering from drought.
(Read my article how to water lemon trees to learn how to establish the optimal watering frequency for your climate).
Indoor Lemon Tree Leaves Curling
Lemon trees are tropical plants that are not cold hardy and therefore grown in pots and taken indoors over Winter for protection from frost.
However there are some specific conditions indoors that tend to cause a lemon trees leaves to curl and even drop off.
The conditions that cause leaf curl for indoor lemon tree are:
- Dryer air with low humidity. Lemon trees are native to tropical climates and prefer some humidity. Indoors the lemon tree leaves have to contend with air currents from air con, forced air and radiators which sap the moisture from the leaves. The lemon tree reacts by curling its leaves to conserve moisture. This often results in a lemon tree losing some of its leaves.
- Sources of heat causing fluctuating temperatures. Indoors in Winter we often turn on the heating at home in the evenings. This is at odds with the daily cycle of temperature change that a lemon tree experiences when outdoors which causes stress that manifests in curled leaves. The sources of heat also increase evaporation from the soil which dries the plant out and results in shriveled leaves.
- Less light indoors. Lemon trees prefer full sun so they often suffer from shock reacting lower light levels indoors which causes stress.
- Transplant shock. Lemon trees leaves can curl as a reaction to a sudden change in environment as there is a significant contrast between the conditions of the outdoors and your house. It is the drastic and sudden contrast in conditions such as temperature, that is responsible for the leaves curling.
How to Revive an Indoor Lemon Trees with Curling Leaves
Indoor potted lemon trees can recover even if some of the leaves are starting to drop or turn yellow. The key is to address the moisture balance and mitigate shock of being moved indoors.
- Spray the leaves with a mist sprayer. This is one of the most effective ways to revive curled leaves as it effectively increases the humidity to replicate the preferred conditions of the lemon tree. Spray with water as frequently as twice per day to ensure the leaves stay moist whilst it acclimates to your home and to mitigate water loss from the leaves.
- Ensure that the lemon tree is not in any direct airflow from air conditioning or forced air. The lemon tree should be in a sunny window with and out the way of air currents. Mist the leaves regularly.
- Increase the frequency of watering. Lemon tree become habituated to a watering frequency outdoors but their demand for water increases when they are brought indoors which causes the leaves to curl as a sign of stress. Lemon trees prefer the top two inches of the soil to dry out between bouts of watering in the Winter because of the reduced rate of growth, however lots of heat indoors can drive evaporation and cause the pot to dry out more quickly. Monitor soil moisture regularly and as soon as the top two inches of the soil are dry give the tree a good soak.
- Give your lemon tree time to acclimate to indoors. The shock of being moved indoors causes stress to the lemon tree but as long as it is located in a sunny window, watered the according to its conditions and the leaved are sprayed regularly then it should revive.
Some leaves can drop off after they have curled up as this is the lemon trees way of conserving moisture.
Do not worry if this happens as new leaves emerge in the Spring in reaction to more hours of light, if the tree is cared for properly.
(Leaves can drop from lemon trees for several different reasons so I wrote another article on what causes lemon trees to lose their leaves and how to save it).
Over Watering Causes Lemon Tree Leaves to Curl and Droop
Lemon trees prefer dryer soil conditions then most fruit trees any are susceptible to over watering which can also cause leaves to curl as a sign of stress.
Typically curling leaves caused by drought also look shriveled in appearance whereas curling leaves from over watering can lose their green color and turn slightly yellow.
(Yellow leaves on your lemon tree can indicate several problems so I wrote another article on what causes lemon tree leaves to turn yellow).
Lemon trees require well draining soil and prefer the top two inches of soil to be somewhat dry between bouts of watering.
Lemon tree leaves curl due to over watering and too much moisture around the roots when:
- Watered too frequently so that the soil is constantly moist. If the soil is damp the leaves tend to curl and turn yellow as a sign of stress. Damp soil also promotes the conditions for fungal diseases such as root rot which can kill the lemon tree.
- Slow draining soils. Lemon trees do not grow well in boggy areas or heavy clay that retain lots of water. They naturally grow in well draining soil with a high organic content and perhaps some inorganic material such as grit for improved drainage. Slow draining soils mimic the affects of over watering causing the leaves to curl, turn yellow and risk root rot.
- Pots with drainage holes in the base. Some decorative pots do not have proper drainage holes in the base which causes the soil to become saturated causing the leaves to curl, turn yellow and potentially drop off as a sign of stress.
- Trays underneath pots of indoor lemon trees. Trays under pots prevent excess water escaping the pot and cause the soil to become boggy which causes stress to your lemon tree.
How to Revive Lemon Trees with Leaves Curling due to Over watering
- Scale back the watering. Only water your lemon tree when the top two inches of soil is dry. Typically this is about once per week but you should determine how often to water your lemon tree according to your climate, and weather conditions. Wait till the soil is dry to a fingers depth and then give the lemon tree a generous soak.
- Lemon tree should be planted in well draining soils. If your tree is in an boggy area then ideally you should transplant it to an area of the garden that is more well draining or the lemon tree is likely to die back. A good potting mix or soil recipe for lemon tree growing is 1/3 multipurpose compost, 1/3 garden compost and 1/3 horticultural grit, sand or perlite. This soil mix replicates the soil conditions of the lemon trees natural environment and provides a good balance of soil nutrients and good drainage.
- Potted lemon trees should be grown in pots with good drainage. If your pot does not have drainage holes in the base then transfer to another pot as a matter of urgency as the curling leaves can turn yellow and the plant can die.
- Trays underneath pots should be emptied of water regularly. Whilst trays under pots can be important to prevent watering spilling from your indoor lemon tree there should not be watering pooling underneath the pot for long periods.
With more favorable drainage and good watering practices the soil around the roots of your lemon tree can dry out somewhat between bouts of watering.
This creates the perfect balance of moisture in the soil for lemon trees and allows the plant to recover.
You should start to see improvement in the curling leaves in the following weeks.
However if the soil remains too damp then the lemon tree is likely to develop the fungal disease root rot causing the leaves to curl, turn yellow and drop off and the plant to die back, hence the importance of knowing how to water properly.
Nutrient Deficient Soil causes Lemon Tree Leaves Curling
Lemon trees are heavy feeders and require regular fertilizer applications in the Spring and Summer to meet their nutritional requirements and to produce the best fruit and flowers.
If there is a nutrient deficit, one of the signs of stress can be that the leaves start to curl, droop, turn yellow and potentially drop off.
Potted plants tend to be more susceptible to nutrient deficiencies, especially if they have been in the same pot for years as the roots exhaust the available nutrients.
Magnesium and potassium deficiencies in the soil are likely to be the specific cause of leaves curling with leaves curling inwards more indicating magnesium and leaves curling downwards indicating potassium deficiency in the soil.
Leaves can also droop and turn yellow due to a lack of nutrients which may look like a curling leaf.
You can of course request a soil test where you send a sample of your soil off to a lab to determine the health of your soil.
Or you can use a citrus fertilizer to address the nutrient deficit.
Use a specialized citrus fertilizer (available at a garden center or on amazon) rather then a multi purpose fertilizer as a citrus feed contains all the nutrients that your lemon tree requires at the right concentrations to avoid over fertilizing which can also cause your leaves to curl downwards.
With consistent monthly applications of fertilizer through the Spring and Summer the lemon leaves should begin to look a lot healthier rather then a curled appearance (always follow the manufacturers instructions).
Aphids and Spider Mites can Cause Lemon Tree Leaves to Curl
There are a few insect pests that can attack your lemon tree and cause the leaves to curl.
If you notice small yellow spots as well as curling leaves then this indicates a spider mite infestation.
Spider mites are more common indoors because of they prefer the dryer environment of houses so often affect lemon trees that have been brought indoors for Winter protection.
Misting the leaves regularly is very effective at displacing the spider mites as they dislike humidity and moisture. Washing the leaves with soapy dish water is also a very effective treatment.
Trim back any severely affected foliage and the tree should recover.
Aphids can also be a problem as they seek to feed off the sap in of your lemon tree which has the affect of curling the leaves.
Aphid attacks are not uncommon on lemon trees and they usually attack the more tender younger leaves, but any serious damage is usually mitigated by a good garden ecology.
There are lots of insect predators (such as ladybugs) which prey on aphids as well as birds.
For a serious infestation of aphids the solution is to use an insecticide such as neem oil which is applied to the leaves of the lemon tree and kills the aphids.
Lemon trees usually recover very well from insect infestations if they are treated. Cut back any leaves that are severely affected and any curling leaves should survive.
- Curling leaves on your lemon tree indicates drought stress due to under watering, excess wind, and low humidity which causes the leaves to curl to conserve moisture. Aphids feed on the sap of young emerging leaves which cause them to curl up.
- Nutrient deficient soil, over watering and transplant shock when moved indoors can cause lemon tree leaves to curl.
- Lemon trees require full sun, regular fertilizer, watering when the top two inches of the soil are dry. Spray leaves can help increase humidity which revives leaves and mitigates damage from pests.
- Use neem oil or a insecticide to treat insect infestations that can cause the leaves of lemon trees to curl.