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5 Reasons Why Orange Tree Leaves Curl (& How To Fix It)

We have an orange tree that’s declining in health and we noticed it started to get curled leaves. To help fix this, I did some research. Here’s what I found.

Orange tree leaves generally curl when the tree doesn’t get enough water. Simply, the leaves curl to conserve moisture. Other causes include extreme weather, pests, and diseases. To fix curled leaves, only water the orange tree when the top 2-4 inches of soil gets dry, and check the leaves for any spots or pests.

So, while orange tree leaves curl for several reasons, how can you tell which issue is affecting your tree and how can you fix it? Let’s take a further look.

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curled leaves on an orange tree

1. Under-Watering

The most common cause of curling leaves on orange trees is under-watering. When under-watered, the orange tree’s leaves curl to conserve moisture and will eventually fall off.

For best results, only water orange trees when the first 2-4 inches of soil gets dry, and apply 2 inches of compost and 4-12 inches of mulch.

Orange trees commonly use more water than other fruiting trees since they prefer to grow in warmer, tropical climates where there’s more evaporation and humidity. While there’s typically sufficient rainfall in tropical climates, a dry spell could cause curling or drooping leaves.

Many times, it’s difficult to tell if you’re over or under-watering your orange tree, but there’s a good trick to find out.

Push a finger 2-4 inches into the soil under the drip line of your orange tree. If the soil is bone dry, your tree needs more water. If the soil is sopping wet 1+ hours after watering, the tree needs less water (and more drainage). The goal is for the soil to have the same moisture as a wrung-out sponge.

So, before you water your orange tree, push a finger into the soil and check its moisture. By only watering when the soil is dry, you’re ensuring the orange tree gets the appropriate amount of water.

Poor Drainage

If you find that your orange tree’s soil is staying sopping wet 1 or more hours after watering it, amend the soil with 2 inches of each sand and compost to improve drainage. While this can take some time, it’s better than risking transplant shock by digging up mature orange trees.

However, potted orange trees that are waterlogged can be repotted with fresh potting soil as a quick fix.

Once the soil is well-draining, apply 2 inches of compost and 4-12 inches of mulch to the top of the soil, under the tree’s canopy.

Compost greatly improves the soil’s richness and therefore water retention. Every 1% increase in the soil’s richness can hold an additional 20,000 gallons of water per acre (source).

Mulch dramatically reduces evaporation from the soil and protects the soil (and beneficial soil life) from drying out with the sun and wind. This water retention goes a long way, especially in the hotter, tropical climates where orange trees like to grow.

Some good mulches for orange trees are leaves, bark, straw, pine needles, and grass clippings.

When you apply compost and mulch, make sure to keep them at least 3 inches from the tree’s trunk to prevent mold and disease from spreading.

2. Extreme Weather

USDA hardiness zone map
Source: USDA

Orange tree leaves curl with extreme hot or cold weather or major swings in temperature of 30ºF or more. Typically, orange trees grow in temperatures between 35ºF to 90ºF and can get stressed if their temperature falls outside of this range.

For the best chance of growth and preventing leaves curling, keep your orange trees within 60ºF to 80ºF if possible.

Hot Weather

A hot and dry climate affects orange trees by drying out the leaves faster than the roots can send moisture. When this happens, the leaves get scorched and curl to conserve moisture.

If they get too hot for too long, the leaves will die and fall off the tree.

If your area gets too dry and hot for orange trees (commonly over 90ºF), there are some practices you can use to help cool them:

  • Provide shade in the afternoon when the sun is at its hottest. You can shade the tree with an umbrella, shade sail, or other trees. Since we’re protecting the tree from the afternoon sun, shade from the west if possible.
  • Apply 2 inches of compost and 4-12 inches of mulch on top of the soil to make sure it stays moist and doesn’t dry out in the sun and wind. Hot days with strong winds act like a blow dryer and can dry the soil (and tree) out in a matter of an hour.
  • Plant in a north-facing direction if you get too much sun. If you can’t provide some shade for your orange tree, planting it facing north will minimize the sunlight it receives (just make sure it still has at least 4-6 hours to properly grow and fruit).

Cold Weather

Cold weather is less likely to cause leaf curl on orange trees, but it’s still possible. While orange trees are typically hardier than other citrus trees, freezing temperatures can stress the tree and cause curled leaves. This is especially true if temperatures fall below 20ºF.

To help your orange trees during frost, consider some of these cold-weather tips:

  • Insulate orange trees in times of frost. Planted orange trees can be wrapped with cardboard or bedsheets, while potted orange trees can be brought inside or buried in the ground. If you bring it inside, avoid placing it near the central heat as it will dry the tree and its leaves out (this happened to my potted Meyer lemon tree).
  • Plant in a south-facing direction to maximize the sunlight the tree receives.
  • Plant along a southern-facing wall to reflect the sunlight and warmth onto the tree. The wall radiates heat even into the night.

3. Transplant Shock

If an orange tree was recently planted or repotted, and it now has curled leaves, it’s likely due to transplant shock. Transplant shock occurs when the plant is exposed to a new environment and has to establish a new root system.

Avoid transplanting unless necessary as it can take up to 1 year for recovery.

Like many plants, orange trees are vulnerable to transplant shock. To help avoid this, I like to plant with the following steps in mind:

  1. Have the new ground (or pot) prepared
  2. Remove as much of the tree’s current topsoil as possible, without damaging the shallow roots
  3. Grab the base of the tree’s trunk and wiggle lightly
  4. Using your other hand, scoop up and support the rootball
  5. Lightly place the tree in the new ground (or pot) and fill it in
  6. Make sure the soil is at the same level on the trunk as before
  7. Apply 2 inches of compost and mulch to the top of the soil
  8. Water generously and add more soil as needed

Generally, as long as you avoid damaging and breaking the roots, and you keep your orange tree comfortable during the move, the amount of stress from transplant shock will be reduced or eliminated.

4. Pests

Aphids

a ladybug eating an aphid on a citrus tree
A ladybug eating an aphid.

Aphids are small bugs that suck the sap from underneath the orange tree’s leaves. This loss of sugar and moisture causes the leaves to curl, discolor, and drop. They also deposit honeydew, which attracts ants. If left unchecked, aphids can damage the orange tree’s health and potentially stunt or kill it.

These bugs come in multiple colors including white, yellow, or black, and usually hide underneath the leaves. Typically, aphids won’t cause damage to the fruit, but because they suck sap from the trees, they can compromise its health and therefore reduce fruit size.

The best ways to get rid of aphids on orange trees are by spraying the infected leaves with water or neem oil, or by releasing ladybugs (a natural predator of aphids). Most often, a jet of water is enough to get rid of them, but neem oil is a good second option.

For example, when my potted Kaffir lime tree had aphids, I found that a jet of water was enough to blast them off and prevent them from coming back. All I did was remove the hose nozzle and used my thumb to increase the pressure. Keep in mind that too strong of a blast will damage the leaves.

Citrus Leaf Miners

leaf minor larvae on the leaves of a citrus tree

We recently purchased a young lemon tree from our local nursery, and it soon started to get leaves that curled and dropped. The leaves also had some bumps and white trails. We sent it off to be analyzed and they told us it was leaf miners.

Recommended: How to Fix White Leaves on Citrus Trees

Leaf miners are small white moths that lay larvae to burrow inside of the leaves of citrus trees, causing them to curl and drop. This pest is fairly common in most of California along with Florida and Mexico.

The good news is that leaf minors don’t cause much damage and are only a concern for young orange trees. Once the leaves harden off and mature, the leaf miners won’t be able to penetrate them.

The best way to prevent and manage leaf miners is to encourage natural predators such as beneficial wasps (the non-stinging kind).

You can do this by planting companion plants such as:

  • Fennel
  • Caraway
  • Dill
  • Yarrow
  • Parsley
  • Tansy
  • Zinnia
  • Coriander (cilantro)
  • Queen Anne’s lace
  • Sweet alyssum

Avoid using sprays as they’re not that effective and will cause more damage (instead promoting whiteflies, scale insects, and other citrus pests).

Available insecticides for backyard trees are not very effective and many products leave residues that kill natural enemies, compounding problems.

University of California Agriculture & Natural Resources

Also, avoid pruning leaves infected with leaf miners as the leaves are still functional and feeding the orange tree via photosynthesis. Pruning can cause more damage in this case.

Feel free to prune leaves that are brown as they’re no longer assisting with photosynthesis, but it’s not necessary.

5. Diseases

Bacterial or fungal diseases such as Armillaria root rot and Phytophthora root rot sometimes cause orange tree leaves to curl, yellow, brown, and drop (source).

You can typically spot signs of a disease if the leaves have spots or if the bark is cracking and oozing sap.

To treat these diseases, prune the infected areas and use an organic fungicide.

While diseases can cause curled leaves on orange trees, it’s not nearly as likely as under-watering or extreme weather. However, if you see spots on the leaves or cracked bark, it’s likely a bacterial or fungal infection.

To treat, prune the diseased areas and apply an organic fungicide as directed.

The best time to apply fungicide is right before the tree blooms as the flowers serve as an entryway into the tree’s immune system.

If you do find that your orange tree is affected by a disease, and you’re looking for a good, organic fungicide to use, check out this homemade, non-toxic fungicide by Stefan Sobkowiak – The Permaculture Orchard.

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