Lemon tree leaves turning yellow

Lemon trees are one of the most popular fruits around the world, beloved for their stunning color and versatility. Great for growing in containers either indoors or out, these trees are ideal for newbies looking to try fruit growing. But most growers end up asking themselves, “Why are my lemon tree leaves turning yellow!”

Unfortunately, lemon trees are prone to quite a few growth problems, one of which is yellowing leaves. There are a number of reasons for this common problem, usually relating to nutrient issues like deficiency or overwatering. Changes in temperature, pest problems and age or seasonal changes are also potential causes, along with less likely issues like lack of sunlight or underwatering.

Take a look at these potential causes to identify which is most likely for your tree. Before making any drastic changes, ensure you know the root cause. Any incorrect alterations in care under stress can lead to even more issues with growth down the line.

Nutrient problems that lead to yellow leaves

Making delicious lemons is not easy work. Trees need tons of sunlight and nutrients in order to maintain growth and produce the fruits we are all after. Considered heavy feeders, lemon trees struggle without adequate nutrients, especially when growing in containers. Lack of certain micronutrients, such as iron or zinc, or even macronutrients like nitrogen will cause the leaves to turn yellow.

To start resolving the problem, conduct a soil test. This will give you a better idea of which nutrients are lacking, allowing you to apply a targeted solution. Use the correct fertilizer containing the right nutrients until balance is restored.

Without completing a soil test first, applying any general fertilizer may only exacerbate the nutrient deficiency or imbalance, making it even harder to resolve down the line.

Overwatering leading to lemon tree leaves turning yellow

The next problem also relates to nutrient uptake, but not due to a lack of those nutrients in the soil. Rather, it is the inability of the plant to draw up the required nutrients due to root damage. This root damage is caused by excess water in the soil, usually from overwatering.

Lemon trees do require consistent moisture to produce juicy, delicious lemons. However, they prefer their roots to remain on the drier side rather than drowning in water. When you water your tree too often, oxygen cannot reach the roots. This can also occur when there is a long bout of rain and limited drainage in the soil.

The extra moisture begins to rot the tough roots below the soil, slowly spreading and stopping any water or nutrients from traveling around the plant, leading to yellowing in the leaves.

Ensure your lemon tree is planted in a well-draining area of the garden where water does not collect. When planting in containers, make sure there are enough drainage holes to prevent waterlogging. Never water the tree when the top layer of soil is still moist to the touch.

Pests affecting lemon tree foliage

One thing almost all lemon tree gardeners have to contend with throughout the years is pests. They seem to love lemons as much as we do, causing serious problems as they feed on the foliage and destroy the fruits.

Yellowing leaves are just one of the many signs of pest damage. This usually indicates an issue with various sap-sucking pests, including aphids and scale, that leave discolored and unsightly marks. When growing indoors, spider mites are quite common, easily spotted by the webs they leave behind.

Small infestations can usually be controlled by knocking the bugs off the plant with a spray of water or gently pruning away affected areas. If the problem is more severe, use a natural insecticidal soap or horticultural oil to suffocate the pests and stop them from returning.

Sudden drops in temperature

Lemon trees, like most citrus, prefer warm temperatures and plenty of sunlight to grow their best. They are not at all suited to cold conditions and don’t grow well in any USDA Zones below 9. If your temperatures frequently dip lower than the sub-tropical climate these plants prefer in winter, their leaves will likely turn yellow suddenly before falling off the plant completely.

When growing outdoors, only plant a lemon tree if you live in USDA Zones 9-11. Those in lower zones can still grow lemons, but will need to grow in containers rather than planting in the ground. This will allow you to bring the container indoors during the cooler months to protect the tree from any temperature extremes, limiting problems with yellowing in the future.

Age of the leaf itself

Small amounts of yellowing leaves don’t always indicate a problem with growth or care. Older leaves on lemon trees can turn yellow and drop off the plant with age or during a change of seasons.

If cold weather has just begun to set in around winter, a few yellowing leaves are nothing to worry about. The same can be said for a couple of aged leaves here and there. Only if the yellowing is sudden and covers a significant portion of the plant should you begin to look at the other potential causes to resolve them.

References

• University of Arizona Cooperative Extension, Irrigating citrus trees
• University of Maryland, Growing dwarf citrus
• University of California, Watering avocadoes and citrus