Why Plants Curl Their Leaves and Why (Most of the Time) You Shouldn't Care

Let me take you back to the summer of 2012, during a brutal drought that scorched much of the Midwest. I was growing a tomato called Italian Heirloom for the first time—and honestly, it looked miserable. The leaves curled inward in tight rolls, and no matter how much I watered, it never looked satisfied.

I decided, long before harvest, that I wouldn’t be growing it again.

But come harvest time, I got a surprise. That sad-looking plant—curled leaves and all—was the only tomato in my entire garden that didn’t show a single sign of blossom end rot.

Italian Heirloom tomatoes in perfect form—no signs of blossom end rot.

Later that fall, at a research conference, I attended a talk by a team of cotton researchers who’d also weathered that year’s drought.  In their yield trials, they had noticed something curious: some of their cotton lines looked like they were really struggling while others were seemingly fine. They started documenting the plant responses quantitatively, collecting data on the plants' exposed leaf area, color, temperature—you name it.

And then came the yield data.

To their surprise, the plants with the most severe-looking leaf curl were the top performers. Far from struggling, they were thriving. The curled leaves weren’t a sign of failure—they were a sign of adaptation.

That was my aha! moment. My tomatoes weren’t struggling either. They were doing what plants do best: adapting to their environment.

Once I thought about it, it made total sense. If I stick out my hand to pet a dog and it bites me, I don’t leave it there—I pull it back. If I’m stranded at sea with no fresh water, I don’t feast on salty snacks—I conserve. Survival isn’t about comfort. It’s about smart responses to stress. And in the case of those curled leaves, that’s exactly what the plants were doing.

Leaf curling in nasturtiums—in this case caused by saturated soil.

So, Why Do Plants Curl Their Leaves?

Plants don’t curl their leaves because they’re trying to frustrate us. They do it because they’re responding to something in their environment. Leaf curl is often a physiological response to stress—heat, drought, wind, pests, even transplant shock. The goal is conservation.

By curling their leaves, plants reduce the surface area exposed to the sun, which in turn limits water loss through transpiration. It’s like putting on a hat and squinting your eyes on a blazing hot day—it’s uncomfortable, maybe even a little unsightly, but it’s not a sign you’re failing at life. The same goes for your plants.

The trouble is, gardeners tend to interpret leaf curl as a sign of distress. And while it can sometimes signal a problem, it’s often just the plant doing exactly what it needs to survive the moment.

When Too Much of a Good Thing Backfires: Leaf Curl from Overwatering

We’re often so worried about underwatering that we forget how damaging overwatering can be. Leaf curl isn’t always a sign of thirst—it can also be a plant’s way of saying, “Hey, my roots are drowning down here.”

When soil stays soggy for too long, it can suffocate the roots, reduce oxygen availability, and lead to poor uptake of water and nutrients. Ironically, the plant may look thirsty—wilting, curling, or even showing yellow leaves—leading well-meaning gardeners to pour on even more water.

One way to avoid this spiral is to feel the soil before you water. Stick your finger a couple inches down—if it’s still moist, skip the watering for now. Leaf curling caused by overwatering may resolve once conditions dry out, but if root damage has occurred, recovery can take time.

Minor leaf curling in Hensley Settlement tomatoes.  This phenomenon is normal and very common for potato-leaved varieties.

Tomatoes and Leaf Curl: A Match Made in Misunderstanding

If there’s one plant that really knows how to keep gardeners on edge, it’s the tomato. Leaf curl in tomatoes is common—very common—and most of the time, it’s completely harmless.

Dr. Carolyn Male, tomato expert and author of 100 Heirloom Tomatoes for the American Garden, writes:

“The most common reason for curling leaves is that the variety carries what is called the 'wilty gene.' This is perfectly normal—most modern hybrids have this gene... Other reasons why leaves curl include a heavy fruit burden, and too cool, too hot, too wet, or too dry growing conditions.”

In other words, tomatoes curl their leaves for just about any reason. It doesn’t necessarily mean they’re thirsty, sick, or malnourished—you probably just looked at them wrong. (Just kidding. Sort of.) There's no need to worry—curled leaves alone have no detrimental effects on plant growth or fruit development.

That said, there are times when you should pay closer attention. If the curling is extreme—like the leaves are forming tight little tubes rather than just rolling or folding slightly—it may be time to investigate. Aphids can cause this type of damage by feeding on the plant’s juices, often hiding on the undersides of leaves. In that case, a treatment is warranted to prevent long-term stress.

But if your tomato plant has curled leaves and is still growing, flowering, and setting fruit? It’s probably fine. Don’t let a few cosmetic quirks send you into a Google spiral. Most of the time, your tomato knows exactly what it’s doing.

Like tomatoes, potatoes and peppers are prone to leaf curling.  These potatoes seem to have found the sweet spot between too wet and too dry.

What About Peppers, Potatoes, and Their Leaf-Curling Friends?

Tomatoes may be the drama queens of the garden, but they’re not the only ones who curl their leaves at the first sign of trouble (or change, or life, really).

Peppers, for example, often curl their leaves when they’ve had too much water, not too little. It’s a common mistake—especially early in the season when we're eager to nurture. Like tomatoes, peppers prefer even moisture but hate soggy feet. If your pepper plants are curling and the soil is wet, hold off on the watering can and let things dry out a bit.

Also worth checking: aphids. These tiny sap-suckers are notorious for camping out on young pepper leaves and causing distortion, especially at the tips. Flip the leaves over and look closely—if you find clusters of soft-bodied insects (or ants farming them), it’s time for action.

Potatoes, being in the same family as tomatoes, have similar tendencies. They’ll curl their leaves in response to hot, dry weather, water stress, or nutrient swings. The good news? Like their tomato cousins, they’re often just adapting. As long as the plants are otherwise healthy and growing well, there's no need to worry.

Cowpea vines with leaf curl caused by herbicide drift.

When Leaf Curl Does Matter

Most of the time, curled leaves are nothing more than your plant saying, “It’s hot,” or “I’ve got this under control.” But occasionally, leaf curl can be a red flag for something more serious—like pests, disease, or chemical exposure.

The trick is knowing the difference between harmless adaptation and genuine distress.

If your plant is otherwise healthy—growing, flowering, setting fruit—curled leaves are usually just a response to the environment. But if you’re seeing other symptoms alongside the curl, it may be time to investigate.

Here’s a quick reference to help you decide whether to take action or simply take a breath:

Leaf Curl Decoder: When to Worry and When to Chill

The Takeaway: Curl Happens

Leaf curl is one of those things that looks worse than it is. As gardeners, it’s easy to assume that every twist or droop is a cry for help—but more often than not, it’s just a sign that your plants are responding to their environment the best way they know how.

So before you panic, diagnose, and treat something that doesn’t need treating, take a step back. Check the whole plant. Look for new growth. Think about the weather. And remind yourself: survival is adaptation.

Not every curled leaf is a problem to solve. Sometimes, it’s just a tomato doing tomato things.

Did you find this article useful?  If so, please leave a comment, then check out our Growing Guides for more helpful gardening tips.