By Jennifer Poindexter
Tomato plants are one of the most popular plants in the garden. Yet, they face many challenges. One of those challenges is curling leaves on a tomato plant.
Have you ever wondered why your tomato leaves curl? If so, you’re in the right place. I’m going to walk you through some of the most common reasons why the leaves of your tomato plants curl.
It’s important to understand the reason for this as it can help you provide better care and protection for your plants and hopefully avoid these issues.
Here are a few reasons which might explain why your tomato leaves are curling:
1. Viral Disease
One thing you must learn early on when growing tomatoes is that the plants are prone to a variety of pests and diseases.
Unfortunately, this can bring hardship to your garden. One reason your tomato plants may have curling leaves is the plant could have contracted a viral disease.
Tomatoes are prone to issues such as mosaic virus, leaf crumple virus, leaf curl virus, and more. There’s no cure for these viral issues, and the plants should be pulled and discarded from the garden.
2. Lack of Water
A common reason to see the leaves of tomato plants curl is that the plant is lacking water. When you grow tomatoes, prepare to provide plenty of water as the plants require it to thrive.
It’s best to water your tomato plants deeply to encourage a strong root system. However, be sure to test the soil regularly and supply more water when the soil is dry to your first knuckle.
As a general rule of thumb, ensure your tomato plants receive approximately two inches of water each week to remain healthy, happy, and to keep the leaves from curling.
Herbicides are hard on tomato plants. Therefore, if you live near commercial farm areas, you might run into this issue.
The wind can grab the herbicides applied on nearby fields and drift them onto your property and plants. This may result in the curling of the leaves of your tomato plants.
You may also encounter herbicides if you purchase mulch or compost where the materials used to make these products were once treated with herbicides. Choose the products you use carefully to avoid this issue.
Should you live near a field where herbicides are used, it may be best to grow your tomatoes in a sheltered location such as a greenhouse.
4. Wind Damage
Winds feel great on a hot summer day. Yet, if you live in an area with strong winds, it can cause your tomato leaves to curl.
As the winds blow, they can cause debris to fly around and lower the humidity. When you have warmer temperatures and lower humidity, this impacts your plants.
You shouldn’t worry about this too much because, typically, when the winds die down the conditions will correct themselves. In turn, your tomato plants should correct themselves as well.
5. High Temperatures
Do you live in an area where the summer temperatures become extremely hot? If so, you may notice your tomato plants have curly leaves on the hottest of days.
This is a typical reaction from tomato plants. They’ll curl their leaves to stop the loss of water. It’s a pretty neat survival trick.
In times of extreme heat, it’s best to provide afternoon shade to your tomato plants. Plus, it wouldn’t hurt to water them deeply a little extra throughout the week.
When I see curling tomato leaves, another thing that comes to mind is pests. If your tomato plants have pests hanging around them which are sucking the sap from their leaves, they’re going to curl.
Tomatoes are commonly impacted by spider mites, aphids, and whiteflies. All of these pests can lead to curling leaves.
Should you see these issues hanging around your tomato plants, treat them with an insecticide or by spraying with soapy water immediately. The sooner you treat the problem, the sooner your plants can return to a normal, healthy state.
7. Too Much Nitrogen
Sometimes gardeners get heavy-handed with their fertilizer. At times, they even supply the wrong type of fertilizer.
When it comes to fruiting plants, it’s good to keep things balanced or to supply a little extra phosphorus, to encourage fruiting, and a little less nitrogen, as this encourages stronger growth of the foliage.
If your tomatoes have received too much nitrogen, the leaves will begin to curl, the plant will turn dark green, and the foliage will become thicker.
In these cases, you must ride out the rest of the growing season. The next growing season, be sure to test your soil prior to amending or adding more fertilizer to your plants.
If the leaves of your tomato plants curl right after transplanting them to a new growing location, your plants are most likely suffering from shock.
This can occur when a plant is moved from one growing location to another. Therefore, the situation should correct itself once the plant becomes settled.
In the meantime, provide optimal care to the plant to help the roots become established. Also, be sure to harden off any new plants prior to transplanting.
9. Nutrient Deficiency or Root Rot
Did you know you can tell what’s going on with your tomato plant based upon the direction the leaves are curling?
If the leaves are curling down instead of up, this is a hint that the plant is struggling with some type of deficiency.
The leaves will also turn yellow in some cases. If your tomato plants have leaves that are discolored and turning down, it may be wise to add a fresh application of compost or an all-purpose fertilizer.
You may also check the growing location. If the plant is left in an oversaturated state, it’s possible your tomatoes are facing root rot.
In these instances, your plants should be pulled up and transplanted into a location with better drainage.
10. Over Pruning
Our last reason as to why your tomato plants may be struggling with curling leaves is you’ve pruned with a heavy-hand.
Pruning is necessary to keep your tomato plants healthy throughout the growing season. It helps ensure there’s ample airflow around the plants to avoid fungal issues from developing.
However, if you remove too many leaves, the plant may not have enough foliage to perform photosynthesis. This is how a plant makes its food.
Therefore, this could cause the plant to become stressed. It’s common to see the leaves curl on weaker or younger tomato plants which have been heavily pruned.
In short, prune your tomato plants but do so with care as the goal is to improve the health of the plant and never to hinder it.
You now have ten reasons why the leaves of your tomato plants may be curling. Evaluate your personal situation and see if you can identify any of the signs of the issues listed above.
Once you have a good idea as to what might be causing the issue, take steps to rectify the problem. Your tomato plants can hopefully make a turn for the better and allow you to enjoy a bountiful harvest from your garden.
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