5 Reasons Your Tomato Leaves Are Curling (Plus How to Save Your Plant)

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5 Reasons Your Tomato Leaves Are Curling (Plus How to Save Your Plant)

Curling tomato leaves are definitely not something to ignore. Loads of lush foliage help your plant produce all the deliciously ripe tomatoes you’ve been patiently growing. But when you see leaves curling on your tomato plants, your harvest could be at risk. Those curled up leaves are a sign that something is not right in the environment or within the plant itself. First, take a closer look to figure out why your tomato leaves are curling. Common culprits include not enough moisture, nearby herbicide use, and diseases. Here are the top 5 causes for tomato leaf curl and what to do about each problem.

tomato plant with curling leaves

1. Tough Growing Conditions

Nature can throw a variety of challenges at tomato plants as they grow. Less than ideal growing conditions are the most common cause of tomato leaf curl, according to experts, and also the easiest to remedy. “Leaf curl is primarily driven by hot weather, lack of moisture, and heat stress, ” says Dr. Ajay Nair, Extension Vegetable Specialist at Iowa State University. In overly hot and dry conditions, the leaf margins roll upwards. Nair says that you’ll usually see curling more on the lower leaves.

The science behind this stress-induced leaf curl reveals that it’s a way that plants actively protect themselves. When hot, dry conditions persist, tomato plants are not able to take up as much water as they lose through evaporation. This internal water deficit causes leaflets to curl up. A curled leaf absorbs less of the sun’s energy and loses less water. Leaf curl is actually a self-defense mechanism.

What to do: Reducing environmental stress that causes leaf curl can help the problem and prevent it too. Start with good watering practices. Aim to provide tomato plants with 1 inch of water a week. If plants don’t receive that amount from rainfall, supplement by delivering water right to the root zone with a hose or drip line. Avoid overhead watering to prevent the spread of disease. Add a 2-inch layer of mulch around tomato plants to limit soil moisture evaporation.

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Leaf curl brought on by tough growing conditions usually resolves when the conditions improve. Don’t expect long-term effects. A short battle with leaf curl “does not significantly reduce plant growth or yield,” says Nair.

2. Too Much Pruning

While pruning tomato plants can help promote fruit development, it can cause problems when too much foliage is removed at once. The plant senses the sudden loss of energy-generating leaves and then curls its remaining leaves as a stress response.

What to do: The best remedy for excessive pruning is to water the plant well and give it time to recover. Let new leaves remain. The plant should return to good health in a couple of weeks.

3. Transplant Shock

Moving seedlings or young starts into your garden can stress tomato plants. Temperature fluctuations and root disturbance associated with transplanting cause some tomato varieties to curl up their leaves in self-defense.

What to do: Plants often recover on their own from leaf curl caused by transplant shock within a couple of weeks. Provide plenty of water as your tomatoes settle in. To minimize transplant shock in the future, make sure to slowly acclimate seedlings to garden conditions before planting, and gently handle the root ball. Do your transplanting on a cooler, overcast day or give your newly transplanted tomatoes some temporary shade with a tarp or other material that will block direct sunlight.

4. Weed Killers

A weed-free lawn could be why your tomato leaves are curling. “Off target drift of herbicides such as 2,4-D or dicamba is a frequent offender,” says Nair. If wind blows weed killer onto your tomato plants, the chemicals will affect foliage growth and may even kill your tomatoes. Plants with herbicide injury have leaves that bend downward and the individual leaflets bend upward in a cup-like shape. This looks different than the tightly curled or rolled leaves caused by hot, dry growing conditions.

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Another source of herbicide-related leaf curl is contaminated compost or mulch. Nair says the contamination comes from long-lived pasture herbicides such as picloram, clopyralid, or aminopyralid within the commercially available compost materials. When the compost is spread over the garden, it can impact tomatoes.

What to do: There is no cure of herbicide-induced leaf curl. Take a “wait and see” approach. Some plants will overcome the effects and produce a crop. plants will die without fruiting. In the future, avoid using weed killers near tomato plants. Know the source of your compost and mulch, making sure to purchase from a reputable dealer.

5. Tomato Diseases

Though not very common, some viral tomato diseases could be why you’re seeing curling leaves. If a virus is to blame, you’ll see twisting and twining new growth, as opposed to curled older leaves common for plants stressed by tough growing conditions. Individual new leaflets often curl.

What to do: There is no cure for tomato viruses. Remove the entire plant from the garden to help prevent spread. In the future, choose newer varieties that offer disease resistance to viruses.

Most Popular Flowers & Plants in the USA

RegionPopular FlowersPopular Plants
Northeast (e.g., New York, Massachusetts)Rose, Purple Lilac, Mountain LaurelSugar Maple, American Elm, White Pine
Southeast (e.g., Florida, Georgia)Orange Blossom, Cherokee Rose, Southern MagnoliaLive Oak, Spanish Moss, Saw Palmetto
Midwest (e.g., Ohio, Illinois)Carnation, Violet, Purple ConeflowerBur Oak, Prairie Grasses, Wild Bergamot
Southwest (e.g., Texas, Arizona)Bluebonnet, Saguaro Cactus Flower, Indian PaintbrushJoshua Tree, Agave, Mesquite
West (e.g., California, Washington)California Poppy, Coast Rhododendron, BitterrootGiant Sequoia, Redwood, Manzanita
Rocky Mountain (e.g., Colorado, Montana)Rocky Mountain Columbine, Bitterroot, Indian PaintbrushBlue Spruce, Aspen, Sagebrush
Great Plains (e.g., Kansas, Nebraska)Sunflower, Goldenrod, Purple ConeflowerCottonwood, Bluestem Grasses, Buffalo Grass
Pacific Northwest (e.g., Oregon, Alaska)Oregon Grape, Forget-me-not, Pacific RhododendronDouglas Fir, Western Hemlock, Ferns

This table includes the most popular flowers and plants in the USA by region, which considers a range of botanical species, including native and widely cultivated varieties.

Most Popular Flowers & Plants in Australia

RegionPopular FlowersPopular Plants
New South WalesWaratah, Bottlebrush, Flannel FlowerEucalyptus, Acacia, Banksia
VictoriaCommon Heath, Waxflower, Pink HeathMountain Ash, Silver Wattle, Victorian Blue Gum
QueenslandCooktown Orchid, Golden Penda, Umbrella Tree FlowerMoreton Bay Fig, Macadamia Nut, Queensland Bottle Tree
South AustraliaSturt's Desert Pea, Kangaroo Paw, Eucalyptus BlossomAdelaide Blue Gum, South Australian Blue Gum, Saltbush
Western AustraliaRed and Green Kangaroo Paw, Mangles Kangaroo Paw, Swan River DaisyJarrah, Marri, Karri
TasmaniaTasmanian Blue Gum, Leatherwood Flower, Tasmanian WaratahHuon Pine, Tasmanian Oak, Myrtle Beech
Northern TerritorySturt's Desert Rose, Frangipani, Desert RoseBoab, Gidgee, Spinifex
Australian Capital TerritoryRoyal Bluebell, Australian Daisy, CorreaSnow Gum, River Red Gum, Black Mountain

This table offers a basic overview of popular flowers and plants in each Australian region, focusing on a combination of state flowers, native species, and other characteristic plants. It's important to note that specific species' popularity and prevalence can vary. This table is a simplified representation. Consulting local botanical gardens or regional horticultural societies in Australia would be ideal for more detailed and accurate information.

Charlotte Gammon

By Charlotte Gammon

Meet Charlotte Gammon, our expert and author. She's our true treasure, as she has got 20+ years of experience in gardening, winery and house design. In early 2000s, she worked for today.com magazine and was in charge of the gaardening section. Later on, Charlotte opened her own designer agency and worked as a designer and decorator. We are happy to have Charlotte with us, as she is our good friend. We value her experience and we're sure you will love the articles she created for our blog.