Lemon trees are treasured for their vitamin-rich fruit and many gardeners love to grow them. However, it’s disheartening when issues arise with your tree.
Leaf curl in lemon trees can happen due to cold snaps or intense heat, as well as pests like scale, mealybugs, mites, or aphids. Too much water can also lead to leaf curling, as can leaf curl disease.
Below, you’ll discover every potential cause of leaf curling and how to address each one.
Not getting enough water can lead to lemon tree leaves curling upwards as the tree tries to minimize the area from which water can evaporate.
You might also notice the leaves turning a lighter shade of green. In extreme cases of drought and heat, the leaves’ edges and tips can start to dry out and curl.
- Make sure your plant gets plenty of water.
- Water the plant once the top 2 to 3 inches of soil feel dry. For lemon trees in pots, try not to let the soil dry out more than 1 inch deep.
- Use 1-3 gallons of water, or however much is needed.
2. Root Rot
Overwatering is a common issue for many plants. Keeping soil wet for too long can deprive roots of oxygen and lead to root rot, disrupting water flow to the leaves.
This may cause leaves to turn yellow and curl downwards, and the tips might shrivel and turn brown. If the tree has fruit, they could start to rot as well.
- Cut back on watering.
- Only water the lemon tree once the top 2 to 3 inches of soil have dried out.
- Ensure the lemon tree has proper drainage.
3. Poor Soil
Since lemon trees are fruit-bearing, they thrive in nutrient-rich soil. Insufficient nutrients can affect both fruit production and the health of the leaves.
When nutrients fail to reach the roots, the leaves can’t properly photosynthesize, leading to yellowing and curling. A common sign of nutrient deficiency is leaves turning yellow with green veins, a condition known as chlorosis.
- Test the soil pH. If it’s too high, aim to adjust it to around pH 6.5.
- Use a slow-release citrus fertilizer that includes nitrogen, phosphorus, potassium, and magnesium.
- Fertilize the lemon tree twice a year, once in spring and again in mid-summer, but avoid fertilizing in winter.
Insects often play a role in causing lemon leaves to curl, with aphids being a prime example. These pests are widespread and tend to target young leaves.
Their feeding activity can make the leaves curl upwards, as aphids are typically found on the underside of leaves, sucking their sap.
- Treat the plant with Neem oil or insecticidal soap.
- Alternatively, introducing ladybugs can help control aphid populations.
5. Extreme Heat
Lemon trees adore warmth and do well in typical summer conditions. However, if temperatures during the growing season swing to extremes—either too hot or too cold—the leaves may suffer and start to curl.
- Slightly up the watering frequency.
- If your lemon tree is in a pot, move it to a spot with partial shade. Once the extreme heat passes, you can move it back to its usual spot.
- For lemon trees planted in the garden, provide temporary shade during the hottest part of the day.
- Applying a layer of compost as mulch can also help protect the roots and maintain soil moisture.
Bacterial blast is a significant disease that leads to lemon tree leaves curling. This disease can attack nearly every part of the tree.
You can tell your tree might have bacterial blast if you see cracked bark on branches, with sap leaking out. Young shoots may blacken, leaves curl and turn red, and eventually, the leaves drop.
Citrus scab is another issue, marked by white bumps on the fruits and leaves. Infected leaves curl and turn yellow in the affected spots.
- Trim away all infected branches and leaves.
- Treat the tree with a copper-based fungicide, applying it multiple times for best results.