Pepper plant leaves curling

Curling Leaves On Peppers: What To Do For Pepper Plants With Leaf Curl

Peppers add heat and a huge range of colors to the vegetable garden, but like their cousins the tomatoes, they can be finicky about growing conditions and sensitive to pest damage. Pepper leaf curl is a common symptom in peppers, as it is in tomato plants. Let’s learn more about leaf curl on pepper plants.

What Causes Leaves to Curl on Pepper Plants?

Pepper leaf curl can result from many different problems, ranging from pests and viruses to environmental stress.


Pests like aphids, thrips, mites and whiteflies cause leaf curl on pepper plants with their feeding activities. Mature leaves may develop spotted or stippled areas, dry out or fall off, but leaves fed on during development emerge randomly curled or twisted, depending on the location of the feeding. Many of these pests produce honeydew, a sticky, sweet substance as a result of their sap-feeding — you’ll notice a shiny clear coating of material near feeding sites.

These pests are easily treated with insecticidal soap or neem oil. Treat your peppers weekly, when ambient temperatures are below 80 F. (27 C.). When you spray, cover tops and bottoms of all the leaves and branches thoroughly, until the soap runs off the plant tissues. Continue treatment regularly until no more evidence of the pests remain.


Viral diseases can cause curling leaves on peppers, among other symptoms like yellow spots, rings or bullseyes on leaves, as well as general unthriftiness. Insect pests carry viral agents between plants, spreading these incurable diseases far and wide. If you suspect a virus, immediately remove the infected plant to help prevent further disease spread and keep pests under control. Viruses aren’t usually present in the soil, so if you catch it early in the season, you may be able to replace the affected plants. Virus-resistant peppers are available from most nurseries for gardens with recurrent virus problems.

Environmental Stress

Environmental problems are often at the root of pepper plants with leaf curl. Pepper leaf curl regularly appears on hot days, during the middle of summer; hot winds combined with low humidity cause leaves to cup in self-defense. If leaves curl only in response to heat, try adding extra water during the middle of the day to keep the plant’s tissues cooler.

Herbicides are sometimes responsible for curling leaves. Always be careful where you spray; make sure that there’s no wind and that run-off won’t end up in your garden. Garden products like compost and mulch that have been treated with herbicide can also cause damage on sensitive plants like peppers. If your plant survives the herbicide exposure, it should produce a small crop despite the damage. Be more careful with herbicides in the future.

If you are puzzled by curling leaves on plants in your garden or landscape, you may need to do some detective work to figure out the cause. Curling leaves can be caused by many problems, including insect damage, disease, abiotic disorders, or even herbicides.


There are several insect pests that cause leaves to curl when they suck plant juices of new or young leaves that are still growing. These include aphids, thrips, and whiteflies.

Peach leaf curl

If you have peach or nectarine trees and see curled, reddish, puckered leaves, your tree likely has a disease called peach leaf curl. This plant fungus affects only peach and nectarine trees.

Abiotic damage

Leaf rolling in vegetable plants like pepper, eggplant, and tomato is very common during wet spring conditions. This isn’t caused by a disease, and no action is necessary.


When spraying for weeds, herbicides (weed killers) can accidently drift onto or come in contact with desirable plants, causing damage. Herbicides containing active ingredients such as glyphosate and 2,4-D can cause leaves to curl.

Determining the Cause

For further help in finding out what is causing leaf curling on your plant, use the UC IPM plant problem diagnostic tool. This easy-to-use tool contains useful photos and will help narrow down and diagnose the problem.

Leaf curling can sometimes be a difficult problem to diagnose. If you’re stumped, contact your local UC Master Gardener Program or UC Cooperative Extension Office.

Pepper Leaves Curling

About Leaf Curl

The term ‘leaf curl’ is often used by gardeners and farmers to describe a common symptom in plants. Peppers and tomatoes are notorious for exhibiting leaf curl when something is wrong.

It can manifest different ways. Sometimes it begins at the top of the plant. Other times it affects all of the foliage. The leaves curl down spiraling in on themselves. Sometimes the tips of the leaves curl up at the same time creating a crumpled look. The leaves may bubble, turn a different color, or eventually die and fall off.

Diagnosing leaf curl is only half the battle. Gardeners must find out what is causing this symptom and address the root problem. It can be a number of different issues.

  • Pests
  • Disease
  • Water Stress
  • Transplant Shock
  • Over-Pruning

Inspect the affected plant for bugs. Pest insects tend to cluster on the undersides of the leaves. Bugs that feed on your foliage will cause leaf curl just from physical damage. If a leaf was fed on as it grew it will develop a twisted and curled appearance. Here are just a few common pepper plant pests.

Aphids are small beetles that can be difficult to see. They come in many colors including green, brown, yellow, red, and black. These bugs excrete a sticky substance that trails along behind them.

Mites can be hard to find because they are so small. They typically look like little brown or black dots that move when prodded.

Plant-eating thrips are small winged insects with long bodies. They can be almost transparent looking. Thrips damage tends to curl and create white patches on leaves. Thrips can carry tomato spotted wilt virus.

The positive aspect of finding bugs on your curling pepper plants is that something can be done about it. The garden is an ecosystem and where there are plant-eating insects there should also be predatory insects. In a highly diverse garden, most pest situations sort themselves out before the plant is badly damaged.

In the event of excess pest damage, consider purchasing colonies of predatory insects like ladybugs, praying mantis, or predatory mites.


A disease issue is the most difficult to diagnose and correct. One reason to keep pest populations down is their ability to spread disease. If you live in a highly agricultural area where commercial peppers are grown, the chances of disease reaching your garden are higher. Take extra care to encourage diversity in the garden. Be observant for the first signs of virus-related problems.

Mosaic viruses can be identified by the mosaic-style pattern left behind on the curled foliage. Different strains affect the plants differently. The curly top disease affects the tops of plants causing leaf curl and yellowing. These diseases are viral not fungal.

Unlike some fungal disease that can be remedied, viruses are incurable. Rule out all other causes of leaf curl before concluding that you have a virus and pulling your plants. If you do have a viral disease, pull the affected plants and sanitize all your garden tools to avoid spreading it.

Water Stress

Over or under watering causes stress to peppers. These fruits are sensitive and require consistent moisture. Keep the soil moist but avoid allowing water to pool. Maintain good drainage in your garden soil and stick to a watering schedule for the healthiest pepper plants.

Transplant Shock

When it’s time to bring starts from the greenhouse or nursery to the garden, make sure they are ready. If plants experience drastic changes, leaves will curl and growth will slow way down. Always make sure that plants are well acclimated before transplanting.

Acclimating seedlings is the process of introducing them to direct light, temperature changes, and wind. Elements they will not be used to if sprouted indoors or in a greenhouse.

Over Pruning

In some cases, gardeners can get carried away with pruning and damage plants. Try not to take more than one-third of the plant’s foliage at any time. Prune a little bit each day over a longer period rather than doing one drastic pruning. The time between cuttings will allow the plant to recover and re-direct energy.

What Causes Curly Cannabis Leaves And How To Cure Them

Cannabis plants can’t vocalise a call for help—but they can send signals to tell you all is not well. If you see leaves either clawing or curling, there is trouble with the trees. Don’t ignore their pleas. This blog will help you identify the causes and cures for curly cannabis leaves.


Overwatering will literally drown your plant’s roots. Excess water will not only rinse most of the beneficial microbes from the medium, a sodden substrate can also become colonised by algae and nasty fungi. Persistent overwatering invariably invites the parasitic Pythium, better known as root rot. Cannabis plants with droopy, claw-like leaves could be trying to tell you they are waterlogged.


“Water mould” microorganisms are just like vampires; you have to invite them in before they can do any harm. Keep them out of the garden by making sure they are not welcome. Maintaining an effective wet-dry cycle is all it takes. If you can pick up your pots, do it. Then you can tell by their weight when it’s time to water.

If you can’t lift the containers, then consider a moisture meter and make sure to carefully monitor post-watering plant behaviour. Try reducing the volume of water. Alternatively, take longer intervals between waterings. Unfortunately, Pythium is virtually incurable and will turn your plant’s roots into brown sludge. If you see droopy, curly cannabis leaves, especially with young plants, look to the roots for answers.


A heavy-handed approach to nutrients is ill-advised. Excessive doses of nitrogen-rich vegetative growth base nutes can cause clawing in leaves. Sometimes, they will even canoe. Similarly, overdoing it with the phosphorus and potassium during flowering will cause curly cannabis leaves and scorch the tips. Chlorosis is a common symptom in both cases.

Dial in feeding. Easier said than done right? Wrong! Almost every brand of well-known cannabis fertiliser offers a feeding chart free to download from their respective websites. Granted, not all cannabis varieties will respond in the same way to fertilisers.

It’s better to start low and go slow. You can incrementally increase doses without seeing leaves curling or clawing. But if you dive right in at maximum strength, you can expect plenty of curly cannabis leaves that will probably die and eventually drop-off.
It should go without saying, but we’ll say it again for good measure; make sure the nutrient solution is the right pH. That’s about 6.0pH for soil and a more precise 5.8pH for coco/hydroponics.


Heat stress can occur indoors or outdoors. If you see curling and nasty-looking brown fringing, your cannabis leaves are sending you a distress signal. Cannabis plants can photosynthesise efficiently at moderate temperatures up to 28°C. Anything above 30°C and your plants are in the danger zone. Combine this with low RH and you’ve got real problems. New leaves will grow gnarly and old leaves will curl yellow and maybe even burn to a rusty, brown crisp.

Indoor growers must constantly maintain the optimal environmental conditions. This starts with optimal light distance. The only way to keep the plant canopy in the sweet spot is to measure and adjust until mature plants peak in height during mid-late bloom, depending on the strain. Moreover, indoor growers can utilise air-con and fans to keep the grow-op cool.

Outdoor growers confronted with heat waves and drought conditions have less control than the indoor grower. Constructing a simple screen shade will keep plants slightly cooler and may prevent leaves from fraying and curling further. You can’t really revive scorched leaves and will have to remove older foliage beyond saving. Also, planting in white pots instead of black pots will keep the root zone cooler.


Cold temperatures can cause curly cannabis leaves too. Eventually, all kinds of leaf discolouration will develop. Sure, cooler nighttime temps late in bloom can add a dash of purple charm to buds, but prolonged exposure to temperatures below 10°C will kill your plants. Flowers will be loose and leafy if plants even make it to harvest. Coupled with high RH, buds will be moist and become vulnerable to Botrytis, AKA bud rot.

Indoors, if temps are too low, you can always add more grow lights and turn a negative into a positive. Outdoor growers might consider an early harvest, or if possible, moving plants indoors at night. Cannabis is a hardy plant species, but outside of the optimal 20–28°C temperature range, leaves will curl or claw.


Genetics are the cause of all kinds of cannabis leaf deformities and mutations. Some strains occasionally have a tendency towards curly leaves or other odd traits. Most growers will thin out these plants. All the shrewd cultivator can do is write it off as bad luck.

Sativa strains and many autoflowering varieties are sensitive to high doses of fertilisers. This is a trait that can cause problems for beginner growers. The solution is to research your reefer. Always find out as much as you can about the genetics of a strain before you decide to grow it. Curly cannabis leaves can be completely avoided if you know how to keep your plants healthy.

Leaf Tips Curling Down

Solving Marijuana Plan Leaf Curl/Cupping Problems
OK rule number #1 when you see this happening is flush with 25% nutrients; use 2 to 3 times the pot size to do this. Flushing means lots of run-off. You use 25% because some elements are not mobile without other elements, so if you have a mag lock up flushing with water won’t get the mag out, as it needs nitrogen to be mobile. Your killing your plants with kindness remember they are weeds. Here are more answers for you, you might want to save it for reference later The only time you don’t use rule #1 is in the last 2 weeks of flower when bottom leaves stop being used for photosynthesis.
Unless another marijuana grower inspects the damage a true assessment might not be possible. It’s hard to tell “exactly” what the culprit is. Unfortunately the “solution” the marijuana grower chooses many times is not the right one.
A misdiagnosis only serves to make matters worse by promoting further decline.
The ultimate and correct solution is in the hands of the marijuana grower.
Here are some common problems when marijuana leaves are curling.

  1. Too much marijuana fertilizer
    The most common cause of marijuana leaf cupping aka leaf margin rolling, leaf margin burn, and leaf tip curl/burn is overzealous use of marijuana plant food. In relationship to factors such as marijuana plant vigour and rate of growth. Leaf burn is often the very first sign of too much marijuana fertilizer.
    A hard, crispy feel to the marijuana leaf frequently occurs as well, as opposed to a soft and cool feel of a happy pot leaf. Back off on the amount and/or frequency of using marijuana fertilizer. Too much marijuana fertilizer can also burn the roots, especially the sensitive root tips, which then creates another set of problems. Note – as soil dries, the concentration of the remaining salts rises further exacerbating the problem.
  2. High Heat
    The marijuana plant is losing water via it’s leaves faster than what can be replaced by the root system. The marijuana leaf responds by leaf margin cupping or rolling up or down (most times up) in order to conserve moisture. A good example is reflected by the appearance of broad-bladed turf grass on a hot summer day, high noon, with low soil moisture levels – the leaf blade will roll upward/inward with the grass taking on a dull, greyish-green appearance. Upon sunrise when moisture levels have returned to normal, the leaf blade will be flat. Lower the heat in the marijuana grow-op and concentrate on developing a large robust root system. An efficient and effective root system will go a long way to prevent heat induced pot leaf desiccation or marijuana leaf margin curling. One short episode of high heat is enough to permanently disable or destroy leaf tissue and cause a general decline in the leaves affected, which often occurs to leaves found at the top of the cannabis plant. The damaged pot leaf (usually) does not fully recover, no matter what you do. Bummer in the summer. One can only look to new growth for indications that the problem has been corrected.
  3. Too much light
    Yes, it’s true, you can give your marijuana plant too much light. Cannabis does not receive full sun from sunrise to sunset in its natural state. It is shaded or given reduced light levels because of adjacent plant material, cloudy conditions, rain, dust, twilight periods in the morning and late afternoon, and light intensity changes caused by a change in the seasons. Too much light mainly serves to bleach out and destroy chlorophyll as opposed to causing marijuana leaf cupping, but it often goes hand-in-hand with high heat for indoor marijuana growers. Turn down the time when the lights on in your marijuana grow room. If you’re using a 24 hr cycle, turn it down to 20 hrs. Those on 18 – 6 marijuana growth cycle can turn their lights down two or three hours. Too much light can have many adverse effects on marijuana plants. Concentrate on developing/maintaining an efficient and robust root system.
  4. Over Watering
    For marijuana growers using soil, this practice only serves to weaken the root system by depriving the roots of proper gas exchange. The marijuana plants roots are not getting enough oxygen which creates an anerobic condition inducing root rot and root decline with the end result showing up as leaf stress, stunted growth, and in severe cases, death. Over watering creates a perfect environment for damp-off disease, at, or below the soil line. Many times marijuana growers believe their cannabis plant is not getting enough marijuana fertilizers (which it can’t under such adverse conditions), so they add more marijuana fertilizers. Making the problem worst. Not better. Often problem 1 and 4 go together. Too much marijuana fertilizer combined with too much water. Creating plenty of marijuana plant problems.
  5. Not Enough Water
    Not only is the marijuana plant now stressed due to a low supply of adequate moisture, but carbohydrate production has been greatly compromised (screwed up). Step up the watering frequency, and if need be, organic marijuana growers may need to water from the bottom up until moisture levels reach a norm throughout the medium. One of the best methods in determining whether a marijuana plant requires watering is lifting the pots. The pots should be light to lift before a water session. After watering the marijuana plants lift the pots to get an understanding how heavy they’ve become fully watered. If the pot feels light to the lift – it’s time to water. Don’t wait until the soil pulls away from the side of the pot before watering. And of course, leach, once in a while to get rid of excess salts. These are the five most common problems marijuana growers encounter when growing cannabis. Correcting the problems early will save the marijuana plants, but may reduce overall yield. With practice and experience these problems are easily overcome which will then enable the marijuana grower to produce fantastic marijuana plants. With heavy yields.

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