9 Causes and Solutions for Tomato Leaves Curling Up In Your Garden

You can’t beat the taste of homegrown tomatoes. They are the most rewarding thing to grow in my garden, as nothing from the grocery store can compare.

Tomatoes are relatively easy to grow and quite hardy once established. However, they are susceptible to various pests, diseases, and environmental issues, one of which is leaf curling. And leaf curling can mean many things. Let’s explore how to diagnose and address this common problem before it becomes a bigger issue.

Overexposure to the Sun or Heat

Ripening tomatoes with tomato leaves curling.
Photo Credit: Envato Elements.

One of the primary reasons for tomato leaves curling is overexposure to sun or heat. While tomatoes thrive in sunny conditions, too much direct sunlight can cause the leaves to curl to protect themselves from excessive heat. When leaves curl upwards, it’s the plant’s way of reducing its surface area to minimize water loss and sun exposure.

If you notice this happening, try providing some shade during the hottest part of the day or moving potted plants to a less exposed area. Using shade cloths can be an effective solution for garden plants. Also, watering your plants early in the morning can help them cope better with the heat throughout the day.

Wind and Other Environmental Factors

Green and red tomatoes ripening.
Photo Credit: Envato Elements.

Strong winds and dust can also damage tomato plants, causing the leaves to curl. Wind can strip moisture from the leaves, leading to curling as the plant tries to conserve water. Additionally, dust particles can block the stomata (pores on the leaves), impairing the plant’s ability to photosynthesize properly.

Ensure your plants are sheltered from harsh winds. Planting them near a windbreak or using a stack of straw bales can help protect them. You can also use row covers or garden netting to shield plants from strong gusts and dust.

Reduced Water Intake

Red and green tomato growing.
Photo Credit: Envato Elements.

Tomatoes need a consistent supply of water, especially when bearing fruit. Inadequate watering can lead to leaf curling. When the plant doesn’t receive enough water, it will curl its leaves to reduce transpiration (the process of water evaporation from the plant surface).

Ensure your plants receive about 1 to 2 inches of water per week, adjusting for container-grown plants and hot weather conditions. Monitoring soil moisture levels around your tomato plants will help them stay happy and healthy. Drip irrigation systems can provide a steady supply of water directly to the roots, minimizing water wastage and ensuring your plants get the moisture they need.

Deficiency in Micronutrients

Green tomatoes on vine.
Photo Credit: Envato Elements.

A lack of essential nutrients can cause tomato leaves to curl and turn yellow. Micronutrient deficiencies, such as calcium, magnesium, and potassium, are common culprits. Calcium deficiency, for instance, leads to blossom end rot, a condition that can be associated with leaf curl.

Adding fresh compost or an organic all-purpose fertilizer can help replenish these nutrients. Rotating your crops and using a soil test kit before planting can also prevent deficiencies. If your soil lacks specific nutrients, consider using targeted supplements like Epsom salt for magnesium or bone meal for calcium.

Signs of Disease

Ripening tomatoes.
Photo Credit: Envato Elements.

Diseases like the curly top virus, spread by leafhoppers, can cause wiry growth and leaf curling in tomatoes. This virus affects the vascular system of the plant, disrupting water and nutrient transport, which leads to stunted growth and curled leaves. Unfortunately, there is no cure for this virus, and affected plants should be removed to prevent spread.

Similarly, the yellow leaf curl virus, transmitted by whiteflies, can reduce tomato yields significantly. This virus causes the leaves to turn yellow and curl upward. Regularly inspect your plants for signs of these diseases and manage insect populations through integrated pest management strategies.

Too Much Nitrogen

Harvested tomatoes.
Photo Credit: Envato Elements.

Excess nitrogen can lead to dark green, curled leaves. Nitrogen is crucial for plant growth, but too much of it can cause lush foliage growth at the expense of fruit production. If you suspect this is the issue, stop fertilizing and let the plant use the nutrients already in the soil.

A soil test kit can help prevent over-fertilization in future planting seasons. Balanced fertilization, with a focus on phosphorous and potassium during the fruiting stage, can help maintain plant health and productivity.

Excessive Pruning

Red tomatoes.
Photo Credit: Envato Elements.

While pruning encourages growth, over-pruning can stress your tomato plants, leading to leaf curling. Pruning removes leaves that the plant uses to photosynthesize and create energy. Without enough foliage, the plant can become stressed and display symptoms like leaf curling.

Ensure your plants have enough foliage to absorb sunlight and avoid pruning young or newly established plants too aggressively. Prune judiciously to remove only the necessary suckers and dead or diseased branches. This will help maintain a balance between foliage and fruit production.

Damage from Herbicides

Red ripe tomatoes.
Photo Credit: Envato Elements.

Tomato plants are sensitive to herbicides. If your plant has been exposed to these chemicals, it can cause the leaves to curl. Herbicide drift from nearby treated areas can affect tomato plants even if they haven’t been directly sprayed. The chemical compounds in certain herbicide products can also have a detrimental effect on the ecosystem and affect beneficial insects like bees.

Avoid using herbicides near your tomato plants. Instead, use natural pest deterrents or companion planting, such as marigolds, to protect them. Marigolds can repel nematodes and other pests that might otherwise harm your tomatoes.

Damage from Pests

Tomato garden.
Photo Credit: Envato Elements.

Pests like tomato pinworms can cause leaf curling by feeding on the plant’s sap. These pests can weaken the plant and introduce diseases. Other common pests include aphids, whiteflies, and spider mites, all of which can cause leaf curling and overall plant stress.

Companion planting with pest-repelling plants like marigolds can help keep these pests at bay. Regularly inspecting your plants and using organic pest control methods, such as neem oil or insecticidal soap, can also help manage pest populations.

Your Best Tomato Year Yet

Smiling girl in tomato garden.
Photo Credit: Envato Elements.

Tomato leaf curling can be caused by various factors, including environmental stress, water intake issues, nutrient deficiencies, diseases, excessive nitrogen, over-pruning, herbicide damage, and pests. Identifying and addressing the underlying cause will help restore your plants to their healthy state. If the leaves are curling downward, it might indicate a different issue, such as root rot or nutrient deficiencies. By understanding these common problems, you can effectively manage and maintain the health of your tomato plants.

Related: 15 Secrets To Growing Killer Tomatoes This Season

Tomato Companions

Dozens of ripening small tomatoes.
Photo Credit: Envato Elements.

Learn More: The Best & Worst Companion Plants For Tomatoes (According to Science)

Benefits of Mulching for Tomatoes

Cooked tomatoes in a bowl.
Photo Credit: Envato Elements.

Learn More: Secrets of Mulching For Your Best Tomato & Pepper Harvests

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