Why Are My Lemon Tree Leaves Turning Yellow?

It may be alarming when you see the leaves on your lemon tree turning yellow, and often it is a signal from your plant that something isn’t quite right in its growing conditions.

Common reasons for lemon tree leaves turning yellow are overwatering, underwatering, inadequate fertilizer, cold temperatures, lack of sun, or pests/diseases.

Published: December 16, 2022.

If you identify the cause of your yellow leaves, you should be able to make some adjustments that will save your plant from any more distress.

The most important thing is not to ignore the yellow leaves and to try to remedy the problem as soon as possible.

Why Do Lemon Tree Leaves Turn Yellow?

Your lemon tree leaves may be yellowing due to a variety of different factors. Often some yellowing and leaf drop occur as the temperatures turn cooler in the fall, but if you notice more yellow than usual, or if your plant was otherwise thriving, the yellow leaves may indicate a deeper problem.

Lemon trees are not deciduous trees that lose their leaves in the fall.

It may be difficult to identify the problem right away, but with a little knowledge and close attention, you will be able to identify and fix the problem–and get your tree back to its deep-green splendor.

Overwatering

Overwatering may cause lemon leaves to turn yellow and then curl up. If your lemon is soaking in soil, its roots may be damaged, and it will lose its ability to absorb water and nutrients adequately.

If your plant is too wet, put it outdoors to dry if it is warm enough, and make sure to let the soil dry out before rewatering. The top three inches of soil should be dry before you water again.

It may be tempting to try to water a lemon tree on a schedule, such as once a week or twice a month, but the frequency of watering will depend on the growing conditions of the plant and may vary according to season, climate, temperature, and other conditions.

Make sure your pot has drainage holes and it isn't sitting in a tray of water. Lemons like soil that is a little gritty. If your soil is full of clay or organic matter, add a little coarse sand.

Underwatering

Lemon trees like to be kept moist but not soaked. They also don’t do well with drying out completely. Keep in mind that potted lemons will lose moisture much faster than those grown in the ground.

Check the soil daily to see if it is retaining the right amount of water. Water your lemon tree when the top 2-3 inches of soil are dry. If the soil looks damp, do not water, as this will lead to overwatering.

The best way to water a lemon is to soak it completely, and let the excess water drain out the holes. Then don't water again until the soil appears dry at the top.

Keep in mind that changing environmental conditions may be contributing to your lemon’s drying out. During the winter, dry air may cause increased drying. However, in bright summer sun, your plant may dry out as well.

Make sure your plant isn’t near an HVAC vent that might contribute to over-drying or temperature fluctuations.

Inadequate fertilizer

Nutritional deficiency can be the cause of many yellowing problems in citrus leaves. Citrus plants require nutrient-rich soil, so if you aren’t adequately fertilizing, that may be the problem.

You can give lemon trees regular plant fertilizer to give the plant some extra nutrients. The best solution, however, is to give it a fertilizer that is developed specifically for citrus trees. You can get this at a garden store or online.

Many expert growers recommend an NPK ratio in the neighborhood of 6-6-6. This means you have equal parts of nitrogen, phosphorus, and potassium. Lemon trees also need nutrients such as iron, copper, nickel, manganese, boron, and chlorine.

Most growers recommend fertilizing lemon trees every 6 weeks or so during the growing season (spring, summer, and early fall) and then not fertilizing during the winter months. Fertilize when you see signs of new growth. Make sure you follow the instructions provided with your fertilizer.

Iron deficiency

Lemon trees are especially susceptible to iron deficiency. You may notice yellow leaves with green veins or mottling if this is the problem. If you suspect this is the problem, you can add iron chelates to your plant's water and see if the problem persists.

You can purchase chelates at garden stores or maybe even hardware stores.

Citrus may also suffer from zinc or magnesium deficiencies, though these should be remedied with the regular use of general citrus fertilizer.

Cold temperature

Cold temps may be the reason your plant is yellowing and dropping leaves, especially if you have recently moved it to a cooler location. A cold tree will have more trouble metabolizing nutrients, which will cause yellowing.

Lemons and other citrus don’t really like to be moved, as they have a hard time adjusting to swings in temperature. Lemons cannot tolerate frost. Keep your indoor trees above 50℉.

If your outdoor tree is too cold, make sure to block it from wind and cold conditions. You can protect a tree with screens, hedges, or plastic sheeting. Lemons planted closer to the house will often stay warmer and be more protected.

Lack of sun

Is your plant getting at least a few hours of direct sunlight a day? If not, inadequate light might be the problem. Citrus trees love sun and can tolerate long hours of direct sunlight.

If you have recently moved your plant, say outdoors to indoors, then lack of sun might be the problem.
If you don’t have enough sun indoors, you can grow citrus indoors with a grow light.

Temperature swings or shock

If you just moved your tree, or if your spring or fall temps are fluctuating rapidly, the tree will probably improve on its own. Make sure you don’t move your tree too much, as shock can cause the leaves to turn yellow.

If the situation doesn’t improve when the temperature evens out, your plant may be too cold, or there may be another reason for the yellowing.

Root bound in the pot

If your lemon tree is growing in a pot that is too small, its roots will not be able to absorb water and nutrients, and it will not thrive. If you haven’t repotted your lemon tree in a while, it may be time to let it stretch out.

Use good soil that is around 10% compost, and that has silt for good drainage, and put your tree in a slightly larger container.

Pests

It is possible that pests such as aphids, mealybugs, scales, or mites are causing the yellowing or browning of your citrus leaves. Inspect your plant regularly for mites. Make sure you look under the leaves for evidence of critters.

If you do find mites, you can spray the tree with dish soap in water, diluted pesticide (from your garden center), or diluted rosemary oil. For minor cases, you may be able to spray the tree with simple water to remove the majority of pests.

Make sure you apply sprays in the early morning or evenings when it isn’t too hot, and the sun is not intense. This will protect your tree’s leaves from any potential damage from fertilizer. Make sure your plant gets enough water after fertilizing as well.

Disease

If you are regularly fertilizing your tree and it has been responding well, the problem may be related to root rot. Root rot is a fungal condition that attacks the roots of a healthy tree, killing them off and making them soft, mushy, black, or smelly.

The best way to prevent pest infestation and disease is by keeping your plant healthy, so it can fight off these conditions on its own. Keep it adequately watered (don't overwater) and give it fertilizer as needed to keep its soil healthy.

Crowding

Lemon trees don’t like certain companions and won’t do well when crowded with other trees or weeds. If that is the case with your tree, try to clean away any cluttering weeds to improve airflow and light around your lemon tree.

You don’t need to mulch around a lemon, and make sure any grass around your tree is trimmed or removed.

How do you Fix Yellow Leaves on a Lemon Tree?

You will have to figure out which cause above is the problem with your lemon tree. It may be good to try one solution at a time so you have a better idea of what the problem is.

If it is summer and your tree isn’t over- or underwatered, you should probably try some fertilizer. If it is winter, make sure your plant is warm enough and getting enough sun. Citrus needs full sun.

Can Yellow Leaves Turn Green Again Lemon Tree?

The older leaves that turn yellow may just turn brown and drop without turning green.

However, if you have identified the cause of the yellow leaves and solved the problem, you should see new growth in spring and summer, and the plant should stop dropping leaves.

Why Are My Lemon Tree Leaves Turning Yellow and Curling?

If you notice curling along with yellowing on your lemon tree, the first thing you should check is whether you are overwatering your tree. This is easy to do. Only water when the first 3 inches or so of soil is dry.

This may mean you are only watering once a month or so in the winter months, depending on your climate (most plants need less water in the dormant season).

How do you Tell if a Lemon Tree is Overwatered or Underwatered?

If your leaves are curling in on themselves and don’t improve after watering, it is most likely that you are overwatering your tree. These leaves will eventually turn colors and will drop from the tree. You may also notice that flowers or fruits turn black.

Let your soil dry out, and then cut back your watering. Water whenever you notice the top several inches of soil are dry.

If your leaves are drying, browning, or curling but are still green or are turning pale green, it is more likely to be underwatering. This would be true if your soil is completely dry several inches below the surface or if your lemon tree pot is lighter than usual due to a lack of water.

Other Issues with Potted Lemon Trees

Sunburn

If your leaves are turning brown or have brown spots, your plant may be getting too intense sun. This may be true in high-altitude places or climates with very intense sun. Move your plant to a spot where it gets very bright light but not a full day of sun.

Compact soil

If you haven’t repotted your citrus tree, the soil may have become compacted, which will not allow the roots to access nutrition and water. If you notice the roots curled around the bottom of the pot, this is a sign that your tree needs a little more space.

In addition, if you notice that the water is not reaching the roots but instead is just pouring around the root ball and out the side of the pot, you will need to repot into a larger pot.

As a rule of thumb, most gardeners recommend repotting a lemon tree every three to four years.

The best solution is to repot with fresh potting soil. Use good soil, include a little compost, and make sure that your pot has at least one drainage hole so that your plant doesn't sit in water.

You can buy soil specially designed for citrus trees, or you can use regular good-quality potting soil. Make sure your soil has a lot of coarse material for good drainage.

Conclusion

If you see some yellow leaves on your lemon tree, don’t panic.

If you pay attention to the tree’s conditions, you should be able to identify the problem with some trial and error and then find a solution. It may take a little patience, but don't give up!