Whether in your house, your garden or their natural habitat, we all like to see plants flourishing and looking their best. Lush green leaves of different shades and varied shapes are one of the most enjoyable aspects of plants.
And the healthiest plants produce the most striking blooms and strongest seeds too. So, it’s important to keep an eye on the health of your houseplants and take swift remedial action when necessary to keep them in tip-top condition.
As always prevention is better than cure and taking good care of your plants is the best way of ensuring they stay healthy.
A healthy plant will be more prepared to fight off infections or infestations and by being attentive to your plants you increase your chances of spotting problems early.
If you notice the leaves on one of your plants beginning to curl up, you know there is a problem. Curling leaves can be a sign of various different problems and it’s important you find the root cause of it as soon as possible in order to rectify it and restore your plant to good health.
Why do plant leaves curl upwards?
There can be many reasons for plant leaves to curl upwards and each requires its own method of reparation. Some of the most common issues responsible for leaves curling upwards are pests, viral infections, an inadequate watering regime, bad positioning, or a lack of vital nutrients.
One thing to check for is whether pests are living on and nibbling away at your plant. Sucking insects like aphids can cause leaves to become distorted leaves and begin to curl. They are usually found on the undersides or the tips of leaves.
Whiteflies are another pest that can cause the leaves of your plant to curl upwards. These pests are almost translucent and can be hard to spot. They too attach themselves to the underside of the leaves, where they suck out the moisture.
To get rid of pests you can spray with insecticide. If you don’t want to use insecticides or find them too costly, you can try using soapy water instead. Repeat applications until all the aphids are gone. For large infestations, it’s often better to remove the worst affected areas.
Pests can be prevented by using sticky traps which will attract them. These traps are often an indication that there is a potential problem rather than a total solution so if you see the sticky traps filling up with pests, it’s time to give your plants a thorough check.
Too much water can cause root rot and lead to the leaves curling upwards. To avoid this, water sparingly and always allow the top couple of inches of soil to dry out completely before adding water. It’s better to give too little water as you can always add more if required, but removing water from soil is not so easy.
When potting your plant, make sure you use a pot that includes drainage holes and place some gravel or stones at the base of the pot before adding soil to help improve drainage.
If the leaves on your plant are curling up and the soil is sodden, remove the plant to check for root rot. If there are any unhealthy looking roots that are mushy, they will need to be removed to prevent the rot from spreading and causing further damage. Use a sharp knife or scissors and make sure you completely remove the rotten roots which should then be discarded.
3. Too much light
Many plants, particularly those from tropical climates, like indirect sunlight. Too much light can cause the leaves to curl up or to turn brown. This is due to a chemical reaction within the plant as a result of excessive photosynthesis.
Think of it in the same way that animals need food, but too much of it will make them unhealthy. The same principle applies to plants. If the older leaves are curling up and the newer leaves are smaller than expected and display brown tips, excessive light is likely to be the cause of the problem.
Try relocating the plant to an area of less direct sunlight or place a net curtain between the window and the plant to take away some of the intensity of the sunlight.
4. Too much heat
Most plants love a bit of heat every now and again, but just as it is with us, too much of it can be damaging. Excessive heat can lead to rapid evaporation which causes the leaves to curl up in an effort to conserve water.
In these circumstances, even regular watering may prove ineffective as your plant may lose water at such a rate that it cannot get the benefits.
Instead of increasing the amount or regularity of watering, consider relocating the plant. A location away from windows that magnify the sunlight, or artificial heat sources such as radiators may benefit your plant.
Alternatively, an open window or a fan may provide adequate airflow and breeze to cool it.
If too much heat is the problem, you will most likely find the leaves towards the top of the plant are most affected.
To prevent plants suffering from excessive heat, monitor the temperature in the room and consider areas where the room may be at its warmest such as near heaters or light sources. You should also provide sufficient space between plants for air to flow.
5. Nitrogen deficiency
Nitrogen is a vital component in chlorophyll, the compound which allows plants to turn sunlight into food. Unhealthy leaves, therefore, can be a sign that your plant is not getting enough nitrogen.
In cases of nitrogen deficiency, your plants’ survival instinct will kick in and it will divert its nitrogen reserves to the newer leaves. This means that the older leaves towards the base of the plant will bear the brunt of the deficiency and will be the ones that curl up.
They may also begin to turn yellow and, if untreated, will then go brown and die. Plants that are near to blooming or producing fruit will often show signs of nitrogen deficiency in the leaves as all its energy is being used elsewhere.
If your plant is near to blooming or fruiting, a dose of high-nitrogen formula in an easy to absorb form should do the trick.
To prevent nitrogen deficiency, it’s recommended that you provide your plants with amino-acid supplements regularly. Amino acids allow your plant to produce protein which helps them to take up nitrogen and put it to good use.
6. Chemical damage from herbicides
If you choose to use herbicides it’s vital that you ensure they are specifically targeted only at the weeds you aim to get rid of. Most herbicides are indiscriminate when it comes to killing plants and any that strays on to your prized plants is likely to cause irreparable damage. L
eaves curling up is one of the first signs of such damage and if you catch it early enough you may be able to douse the plant in water to protect it.
Unfortunately, though, most herbicide damage cannot be rectified and the best solution is to remove the damaged parts of the plant.
If the damage is so severe that removal is not possible, try giving the plant a healthy dose of fertilizer and water to help it try to combat the negative effects of the herbicide.
7. Viral infection
Leaves curling upwards can be a sign that your plant has a viral infection. Infection in plants is usually incurable so it is best to remove the affected ones to prevent further spreading.
Leaf curl is likely to be just one of a number of symptoms obvious on an infected plant. Infected plants should not be disposed of in your compost and after removing them it is advisable to thoroughly check all the plants growing in the same vicinity for signs of infection and remove any that display symptoms.
If any particular plant looks healthy other than a small patch of infection, try removing just the infected sections of it in the first instance. But be sure to keep a close eye for any further signs of infection and deal with them immediately.
Leaves curling up on the edges
Leaves will curl up at the edges to cope with extremities in its growing climate. It often begins with the leaves closest to a hot zone, such as a grow light, or vent, in an effort to regulate the plant’s temperature.
However, any extreme can cause the leaf edges to curl up at the edges. Not just temperature, but also a lack of water in the root system, low or high humidity, or exposure to a cold draft.
The edges of leaves curl first to protect the leaf surface from such extremes to conserve moisture. It is a defense mechanism.
The more exposed the leaf is to an extreme fluctuation to its normal growing climate, the more the leaf continues to curl, eventually, rolling in on itself.
Plant leaves rolling up
Under continued duress from excessive temperatures, plant leaves roll up to the extent that they form a cylinder. This response happens when temperatures rise to extreme levels, such as the high 90°F days of summer.
By forming a cylindrical shape, the number of stomata on the leaf surface that is exposed to direct sunlight is reduced. While the leaf surface is exposed, water would just evaporate rapidly.
The leaf curling prevents that from happening by creating a micro-climate within the cylinder. The stomata are shaded because of the leaf curling.
For indoor plants, fixing rolled up leaves is just a case of moving the plant away from a heat source or correcting the room humidity. The plants most susceptible to leaf rolling are plants that require low to moderate light conditions.
Outdoor plants are not as easy to rectify the growing temperatures of because it is not just the leaves that need some shade. Direct light hitting the soil heats the soil and roots. The warmer the soil gets, the faster water evaporates.
If water is evaporating from the soil before it can be transported to the leaves, the response is going to be the leaves rolling up to conserve what water is available.
The temporary fix for protecting garden plants during a heatwave is to use cloths for shading the leaves from direct sunlight and a straw mulch on garden beds to keep the soil as cool as possible.
There is no substitute for proper care and attention when it comes to maximizing the health and the lifespan of your plant. But there is no guaranteed way of preventing infections, infestations and some environmental factors.
Try to reflect the natural habitat of each plant as best you can in terms of heat, light and watering regime. Consider also the nutrients each would naturally benefit from and ensure you provide these in the most effective way.
As part of your routine, check the leaves, including the undersides for signs of ill health or unwanted parasites.
Read up on the best care package for each plant that you own and try to build up an inventory of common antidotes so that you are as prepared as you can be to tackle the most common problems.
By following these steps you should be able to enjoy many years of healthy plants. If you’re new to keeping houseplants, try not to worry about trying to remember everything all at once.
Remember you can drop by any time to check our plant care guides or for help with troubleshooting. Over time your knowledge will expand and you’ll find that you’re able to diagnose and treat many of the most common issues unaided.
And who knows, you may even find one day that it’s you giving out the advice.
Read about a very special houseplant next: Geogenanthus Ciliatus.
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I am Robert, and I live in the UK. My hiking activities have spurred my passion for all things plants. Walking forest trails and country lanes lined with coniferous plantations with three dogs who love to forage (got to watch for the toxic stuff). I like observing rhododendrons’ botanical beauty in bloom and herbaceous border plants… The dogs would much rather destroy them.