Why are Leaves Curling or Clawing? (“The Claw”)
The following symptoms are for when your cannabis leaves are “clawing” or curling up or curling down. Sometimes known as “The Claw”. I’ll give a short explanation with pictures of each problem, plus links to the solutions! Fix this common (but hard to diagnose) marijuana problem today!
A Nitrogen toxicity is the result of the plant getting too much Nitrogen (usually from too high levels of nutrients overall, or by using a Vegetative nutrient in the flowering stage). It causes dark green leaves and curled tips (“the claw”).
One of the main symptoms of a Nitrogen toxicity is curled tips (“the claw”)
A plant with a Nitrogen toxicity tends to be dark green all over
Caused by too much wind. You’ll notice that the leaves further from the fan don’t have symptoms.
Example of too much wind on your leaves
Bad Soil / Overwatering / Underwatering
You can help prevent over and under-watering your cannabis plants by always starting with good soil or coco coir.
Bad soil is usually thick and muddy. Plants in poor soil will droop (often with unhappy curly leaves) no matter your watering practices.
Avoid thick soil that stays wet for a long time and doesn’t drain well
Overwatering makes leaves fat with water, and they tend to curl down and droop
Overwatering (especially when combined with heat) can also cause leaves to curl up
This plant was grown in muddy soil, and the curling, unhealthy leaves kept getting worse and worse over time!
Underwatering causes symptoms that often look like overwatering, but you’ll know it’s underwatering if the plants perk up each time after you water them.
Although often caused by overwatering, once the roots are sick you’ll see symptoms for a little while even after you start watering your plants properly.
Unhealthy roots can cause all sorts of problems including curling and clawing!
Unhealthy Roots in Soil/Coco
This plant’s roots were damaged from being overwatered and too hot for several days. As a result, the leaves took on a strange, blistery appearance.
This plant suffered from heat combined with overwatering for several days. This damaged the roots and gave it this odd leaf curling.
Root rot is something marijuana hydroponic growers can suffer from if pathogens attack the roots. It is often triggered by heat and/or lack of bubbles near the roots.
Root rot can cause curling leaves and brown patches as well as sometimes other nutrient deficiencies
If a plant stays in the same container for too long, the roots will eventually start wrapping around the edges of the pot. This is known as being “rootbound” and causes symptoms similar to other root problems.
A rootbound plant has been in the same container for too long. Roots wrap around the edges and “choke” the plant.
Rootbound plants often droop, appear yellow, get nutrient deficiencies, and stay small. Even if you’re caring for them perfectly!
If you see tons of white roots when transplanted, that means the plant was in that container too long
When this happens, the main solution is to transplant the plant into a bigger container. Another solution is to grow in fabric pots or air pots. These types of pots let air in from the sides, killing the circling roots (“air-pruning” them) and prevents the plant from getting rootbound for months.
To help a rootbound plant, transplant to a bigger container with fresh potting mix
Or start with air pots or fabric pots in order to prevent plants from getting rootbound at all
If plants are experiencing a lot of heat, it can make leaves droop and/or curl. Some strains can handle a lot of heat, while other strains tend to droop when it gets warm.
Heat can cause leaves to curl up
Read more about heat and growing weed:
Plants can get light burn (sort of like a sunburn) even if the temperature is completely under control. The symptoms are usually concentrated close to the grow lights. Sometimes this can cause leaves to claw and curl downwards.
Light burn can cause the leaves closest to the light to turn yellow
Bugs & Pests
Often a bug infestation caused general plant unhappiness, but these are some of the most likely to cause curling or clawing leaves.
Usually, you can’t see broad mites because they live inside the plant. The main symptom of an infestation is strange leaf curling that is specific to this pest, as well as “wet” looking leaves.
Hemp Russet Mites
Hemp russet mites can also cause drooping and other strange symptoms, but the bugs are so small many growers don’t realize what they’re dealing with.
Hemp russet mites cause drooping and yellow mold-like growth on the tops of plants
A closeup of the hemp russet mites
Fungus gnats look like tiny flies buzzing around your topsoil. Although a few fungus gnats won’t really hurt your plants, a big infestation can damage the roots, causing symptoms similar to other types of root problems.
Learn about the various things that cause cannabis leaf curling or clawing, and get the solutions!
Leaf Tips Curling Down
I am growing 2 pure kush and 2 pre-98 bubba plants in Roots Organics soil, mixed with extra perlite and some dolomite lime, along with Cap’s bennies. The tips on all plants curl down. Some leaves on the pure kush plants also curl down on the sides, kind of resembling an upside down canoe.
I transplanted from one gallon to 3 gallon smart pots a couple weeks ago. They are fed botanicare pbp grow, liquid kelp, em-1 and sea green every 3 days. Every third watering, I feed them aerated compost tea. Temps are at around 80 with lights on and 65 with lights off. I use de chlorinated tap water, and don’t check my ph as I read organic soil adjusts itself to its needs.
I had thrips, but killed them off a few days ago with spinosad spray and they haven’t been back since. Does anyone have any idea what could cause this? They seem to be growing fine (but slooow veg) otherwise.
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.
- 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.
- 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.
- 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.
- 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.
- 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.
I am growing 2 pure kush and 2 pre-98 bubba plants in Roots Organics soil, mixed with extra perlite and some dolomite lime, along with Cap's bennies. The…