At one point or another, you’re going to walk into your grow room or garden and notice your plant leaves curling up. Make sure that you give the plant adequate water and that it has been fertilized enough.
Unfortunately, it’s not entirely clear what the cause might be. However, one thing is for certain – this doesn’t look quite healthy and something more serious might need to be addressed. The foliage of our plants tells us a lot about them – it’s where we can identify nutrient or pH problems. Insects also love to feast on these leaves which is where you’ll identify common pests and plant diseases.
When our plants experience environmental stress, like too much heat or a change in the atmosphere, they can display corresponding changes. With so many leaves changing because of different plant issues being related to them, diagnosing what is causing the problem can be difficult.
A plant with a curl to its leaves could indicate disease, insect damage, excess heat, or fertilizers.
It can be difficult to diagnose problems in the garden or grow room because we observe many similar symptoms. However, it is really important to have the right information so we will talk about how to actually diagnose these problems and work on resolving them later.
1. Due to Excessive Heat & Light
Heat and light stress are risks plants face in many environments. The frequency and severity of these stressors on a given plant can depend on how close your grow lights hang to the plant or the time of day you’re growing at.
Some plants grow better with a proper temperature- not too hot, not too cold. To keep the room at a perfect temperature of around 22-26 degrees celsius, your plants should recover quickly. Novice growers often struggle with the temperature range that is ideal for plant growth. What I know is that a grow light should be kept at a distance from the plants to avoid heat and light stress.
To identify if the heat from your grow lights is causing plants to wilt, look for leaves that are directly under the light that is more crumpled. If you notice that it could be a sign of excessive light/heat stress. If that were the issue, you could try lowering the intensity of your lights or moving them farther away from the plants. If you grow indoors with HPS/MH Lamps then you’ll need to constantly monitor the temperature unless you are using the LED Grow lights which will not produce too much heat.
2. Root problems due to overwatering
One of the most common problems that are caused by overwatering is “root rot,” which is a disease of the plant’s roots. It can lead to wilting, yellowing, and leaf death. One of the most common mistakes that novice gardeners make when growing tomatoes is watering them too much. Giving too much water can lead to plants developing the ‘dreaded tomato leaf roll’.
Overwatering can lead to a variety of issues such as root rot, early blight, wilt, or slow plant growth. One warning sign is if the leaves curl on your plants.
You can tell if a plant is getting too much water or heat stress by looking at the plant in general. If it’s droopy, wilty, and overall unhappy, it could be root rot from overwatering. On the other hand, if it’s wilting and overly stressed from too much heat, then there are bigger problems that need attention.
3. Extreme Humidity is a common cause of leaf curl
A lot of growers are not aware that extreme humidity could cause leaves to curl up. Many growers tend to struggle especially with humidity in grow tents. The problem is when you try to cram plants into a small space. You should keep humidity in the ideal growing range of between 50-70% during veg and 40-50% during flower.
Ignoring this problem can lead to a lot of unwanted fungus, such as bud rot and powdery mildew. Your plants will quickly begin to wither, forcing you to start from scratch.
4. Pests could cause curling on your plant
When the plant leaves curl, it means they are either shocked or dehydrated. If this isn’t caused by your environment (e.g., heat or humidity), you might be dealing with pests. One way that pests can cause your plant leaves to curl up is by sucking the moisture out of the leaves. Mostly aphids, thrips, and whiteflies damage the plants.
More often than not, these pests are developed when you’re growing outdoors. But it is possible to get them indoors too – once they come in they’re notoriously difficult to remove.
By growing in a tent & keeping your environment sealed, you can, to some extent, prevent this. Even with the best control standards and procedures in place, there are still ways you could unintentionally introduce bugs to your grow room. It is important to check the underside of leaves for early indications of pests. If you catch them before they become an infestation, your plants will be much healthier and require less maintenance.
5. Nutrient Deficiency & pH problem
Nitrogen deficiency could cause the leaves to curl either up or downward. It can be hard to spot when the problem is not just a nutrient deficiency. Making things worse by feeding your plants nutrients at a heavier application rate might not be the right solution. One of these nutrients could be locked out by the pH. Adjusting your pH to this range should give you better nutrient absorption. Always follow the feeding chart and keep your pH levels at an optimum to avoid any issues.
After looking at the above issues, now we’ll explain how to remedy plant leaves curling up.
Tomato plants develop curling leaves when they are exposed to high humidity. It’s important to maintain moderate humidity in order to prevent this from happening. Water your plants less frequently, and keep them in a room where there is good air circulation. One of the things that separate experienced gardeners from novices is the ability to identify plant problems that may produce similar symptoms.
For example, some symptoms of tomato plant leave curling up could be due to high heat or an infestation by pests. However, it could also be an indicator of dehydration or insufficient humidity. Rather than just focusing on a few problems at a time, prioritize the concerns that are most pressing and try to tackle them first. As such, you can’t just make a single decision with the plant. You need to take a broader approach to fruitfully increase its chances of survival, otherwise, your plant’s condition worsens quite fast.
Ask yourself the following questions:
This is a great question! Are all the leaves curling up, or only a few of them?
Did the problem only occur in a few plants or all of them are affected? Please identify which plants in your garden/grow room appear to be affected.
What changes have you made to the care of your plant in the last few days?
What potential problems can you rule out?
By asking these questions and narrowing down the potential culprit for your plant leaf curl, you can come up with a more specific plan of attack to remedy the plant leaves curling up.
Here are some tactics to fix each of the potential causes we mentioned above.
Optimize Your Grow Environment
To avoid or fix foliage-related problems, you need to optimize your grow room.
If you’re growing outside, there is little you can do other than hope that mother nature has your garden’s best interests in mind
Make sure you provide your indoor grow room with the proper temperature & humidity levels. Some of the essentials you’ll need are –
- Ventilation System – Every grow room needs an exhaust system (carbon filter, ducting, and a fan) to properly vent excess humidity and smells. It is a necessity if you want your grow room to function well. You can also install an intake fan with a filter (keep pests out) to bring in fresh CO2-rich air for your plants.
- Oscillating or Clip-On Fans – Clip-on Fans are a great way to keep cool by oscillating the airflow, dissipating heat, and releasing the stagnant air all around. For better air circulation and cooler temperatures, try an Oscillating fan. These will energize your plants and prevent stagnant air, making them stronger. You’ll need these to keep the air circulating and at a good temperature in the grow room, decreasing humidity while strengthening stems & branches.
- Dehumidifier – If your grow room is larger and struggling with more humidity, then a dehumidifier would be good to have. This is because it can help in preventing powdery mildew and other fungal problems.
- Air Conditioning – If it’s warmer where you live, year-round gardening indoors can be tough. An air conditioner will be necessary for large grow rooms to keep the climate at the right temperature.
Here are our top picks for the best ventilation systems and clip-on fans. These models will suit both hobbyists and large-scale commercial growers of plants.
6″ Portable 2 Speed Verti-Clip Fan 90 degree Oscillation$55.00 Inc. GST
Sea Hawk Clip Fan 2 Speed 6″ 150mm for Grow Room$25.00 Inc. GST
Mountain Air Carbon Filter 250X1000MM (10″)$389.95 Inc. GST
ISO-Max Fan 150MM (6″inch) With 3 Speed Control$499.50 Inc. GST
Cultiv8 Inline Axial Fan 150MM (6″inch) Ball Bearing$79.95 Inc. GST
Can-Lite Carbon Filter GT 600 Steel 150MM X 540MM$169.95 Inc. GST
Mountain Air Carbon Filter 150MM X 500MM MA0620$189.99 Inc. GST
Mountain Air Carbon Filter MA0820 200x500MM$220.00 Inc. GST
Can-Fan RS150 Centrifugal Fan 150MM (6″ inch)$199.95 Inc. GST
How To Water Your Plants Effectively
Tip: Make sure they are watered enough, but not too much. Make sure the soil is moist, don’t overwater them, and water at the right time of day.
Excess watering is at the root of most curled leaves. You need to water your plants regularly so that they can grow as best they possibly can. The most important part to keeping your plants healthy is making sure they have enough moisture so they don’t wilt, which could be more likely to happen if you neglect them and allow the top of the soil to stay dry.
In cooler climates, the bottom of your container could still be waterlogged. We often use a soil tester to estimate the moisture level of the media. Alternatively, you can simply stick your finger in the potting soil so you can feel the difference between wet and dry.
If the moisture level is halfway up your first knuckle (about an inch), then you can water more. If the moisture is between your first two knuckles, you should not water for now.
Of course, you need the right and good quality grow pots or containers. When looking for the perfect pots for your garden, there are many things to consider such as good drainage and aeration. Fabric pots are recommended since they will dry out quicker than plastic ones. However, take note that hard pots need proper drainage holes and should be placed in a saucer – collect the runoff and dispose of it properly.
16L Flower Bucket Black 300MM$6.99 Inc. GST
52L Bucket with Handle (No Holes) (500mm)$18.95 Inc. GST
Black Solid Round POT 300MM 15L$6.50 Inc. GST
Black Solid Round POT 410MM 28L$9.90 Inc. GST
Fabric Pot 1 Gallon | Great for Hydroponics$3.30 Inc. GST
Fabric Pot 10L | Great for Hydroponics$4.40 Inc. GST
Get Rid of Pest Quickly
If your plant’s leaves are curling upwards due to pests, you need to get rid of the pests as soon as possible. If you have an IPM strategy in place, it will be a lot easier to get rid of them.
Scrambling to save your crop? Take early action before it’s too late by removing sick & unhealthy plants, so at least you can save the ones that aren’t being affected yet.
If that is the case, it’s best to use Pure Crop1, Zero Tolerance, Pyrethrum, or neem oil product you think will be most effective for the job. You can then spray these bugs and bring balance back to your garden.
The insect types that commonly infest growing spaces need to be identified first so appropriate measures can be applied. Here are the most common aphids, thrips, Spider-mites, and whiteflies that damage the plants.
When in doubt, email or call us and we’ll provide our expertise!
Pure Crop 1 Insecticide 100ML | Fungicide | Biostimulant$29.95 Inc. GST
Eco-Organic Garden 100ml Eco-Neem Concentrate$24.95 Inc. GST
ED Rosenthal’s Zero Tolerance Aerosol Spray 525ML$21.95 Inc. GST
Fixing the Plant Nutrients and pH Issues
If the leaves on your tomato plant are curling up, it doesn’t mean it’s a difficult issue. If you suspect the problem is related to nutrition or pH, you can fix it quickly. Usually unlocking nutrients with a good flush is enough to give your plant’s roots a fresh batch of feeding.
What’s great about plants is that they are going to take up whatever nutrients are in the soil no matter which media you use. If you want to start over though, giving your plants a good flush can help get rid of any undesired substances in their root zone. Flushing can really be as simple as completely flooding your media with pure, pH-balanced water for a few feedings.
Tip: For better results, use a Flushing agent either Athena’s Cleanse or Crystal Clear Coco Flush.
The EC meter can be used to figure out if your nutrients are too dense or dissolved, which could cause deficiencies or toxicities.
Our Final Thoughts On Leaves Curling Up
We’ve covered some of the main reasons for curling, and shared some good tips on how to fix these issues.
This usually is a case of too much environmental stress, improper watering or over-feeding, or an outbreak of pests.
Now it’s just a matter of you investigating your own garden. Do some research and come up with a plan to solve the issue in your garden or grow room.
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