One of the most common problems I see when growing citrus trees, including orange trees, is that the leaves start to curl and sometimes even drop. There are a few common reasons, most of which are treatable. In my guide, I going to discuss some of them, including lack of water, too much sun, insect damage from aphids and even Fungal diseases.

Water stress

Are your orange tree leaves yellow and somewhat crispy as well as curling? If so, the problem is probably that you’re under-watering your orange tree. It’s best not to water on a schedule but to wait until your orange plant needs more moisture.

Are the leaves yellowish, still quite plump and curling on the edges? This is a sign of root rot and that arises from over-watering your orange tree. The Orange tree pests and diseases article covers the correct way to water your tree and how to recover from over-watering.

What to do

Check about 3cm down into the soil. If it’s dry at that depth then the plant needs watering. Be sure to water it thoroughly and to drain the excess water off.

Follow the instructions in the article mentioned above for root rot or read my guide on root rot here.

Sunburn leaves

It’s possible for orange trees to get sunburned. This happens when they receive too much daylight or are in too strong a period of direct sunlight (probably noon through the afternoon.) Orange tree leaves curling and turning brown are a sign of this problem.

What to do

Move your orange tree to a more shaded location but be sure that it still receives its allotted six to eight hours of sun per day.

Potassium deficiency

If your leaves are a yellowish colour with the edges bent downwards, your tree may have a potassium deficiency. Other signs of needing this nutrient include slow foliage growth, small leaves and reduced fruit size.

What to do

Apply potassium to the soil in the form of potassium chloride.

Pests and diseases

Infestations of pests and infection by diseases (usually fungal ones) can lead to leaf curl.

What to do

Head over to Orange tree pests and diseases for details on the most common problems in this area and what to do about them. Most insects, including aphids and mealybugs, can suck the sap from orange tree leaves, causing the leaves to curl. They sometimes also leave a sticky substance which I talked about in this guide on why citrus leaves sometimes become sticky.

Nature

Orange tree leaves will sometimes curl downwards in the late autumn or early winter. If you’ve checked all the other problems in this article, then it’s just nature being normal.

What to do

Just take care of your orange tree as normal. See How to grow and care for orange trees for my advice on how to do that.

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