- Oklahoma Planting Zone Guide - July 31, 2022
- Watermelon Season Guide - July 23, 2022
- When to Pick Watermelons Guide: Never Have a Bad Watermelon Again - July 23, 2022
I’ve been there. I’m sure you’ve been there. It’s just what happens when you grow tomato plants – their leaves curl. I used to stress and worry about this, but I’ve learned over the years that this is a really common issue, if you can even call it an issue.
The reality is that leaf curl is usually no big deal. Most of the time, they are a symptom of some easily fixable issue. Since this is such a non-issue, I thought I would share a few of my tips and tricks for dealing with curly leaves. Once you see how easy it is to deal with, I’m sure you’ll be planting dozens more tomato plants this weekend.
Bottom Line Upfront
Hey, I get it; gardening is about being outside in the dirt, not in your office on the computer. If you’re waiting for winter to set in before you dive into research, then just read through this sum-up.
The five main reasons tomato leaves curl are:
- Too much or too little water – learn how, when, and how much to water tomato plants to fix this
- Heat and sunlight – learn to provide your plant with the right amount of these
- Nutritionally imbalanced soil – learn to test and tweak the soil
- Disease and pests – learn to prevent, diagnose, and treat all the things that could attack your plant
- Stressors – learn to properly prune and transplant your tomato plants to prevent shock
Five Reasons Why
It’s time to discuss the reasons why your tomato plants have curling leaves and what you can do about them. As I said before, most of these are non-issues and are easily resolved.
Watering Methods & Balanced Hydration
If your tomato leaves are curling due to hydration issues, then you can relax. This is one of the easiest problems to fix. It’s also easy to diagnose.
Underwatered Tomato Symptoms:
- Dry leaves and stems
- Curling leaves
- Dry and cracked soil
Overwatered Tomato Symptoms:
- Curling leaves
- Soggy soil
- Yellowed leaves and stems
- Soft, squishy leaves and stems
Suffice it to say, tomatoes need a proper system of watering and balanced hydration. These plants consume plenty of water every day, especially when the weather is hot and sunny. Honestly, I don’t worry so much about overwatering my tomato plants because I feel you have to purposefully try to do this. Instead, I purposefully try to ensure my tomato plants are watered using the proper method.
If you want to ensure that water issues are not the cause of curling leaves on your tomato plants, then check out my favorite watering tips:
Always Water in the Morning
When you water your tomato plants during the heat of the day, the water tends to evaporate. This means your plant is not getting all that lovely moisture — the air is. Also, if you water your tomato plants in the evening, there is no chance for excess water on the plant’s leaves to dissipate. Instead, the water will sit on the leaves all night, possibly causing them damage.
Mornings are just the best time for watering. The coolness of the air limits water evaporation, but there is still time for the heat to dissipate any excess water off the plant’s leaves.
Always Water the Soil
When you spray your entire plant with a garden hose, you risk the chance that only their leaves get any moisture. My gardening experiences have taught me that soaking tomato plant leaves does not give the plant the moisture it needs. This type of watering can make things worse. Wet leaves are a playground for fungal diseases and a breeding ground for pests. So, with this in mind, I suggest you aim to hit the roots.
Aiming for the roots also allows you to water the plant slowly and deeply. Tomato plants need plenty of water to reach their deepest roots, but they do not need a deluge of water; they need a gentle flow. Watering with this method in mind will prevent overwatering, damage to the plant and a loss of beneficial topsoil.
To water the soil of your tomato plants slowly and deeply, I suggest you invest in an irrigation system. I like the Rain Bird Drip Irrigation system, but there are plenty of other options if this one doesn’t speak to you. What I like about this system is that it can be customized to the size of your garden and to the watering method it uses. It works great for me whether I need to slowly moisturize soil or spray my shrubs directly.
Always Water According to Stage
Where your tomato plant is in its growth stages will determine how much water it needs. While the quantity doesn’t vary greatly, it is helpful to know how much water a tomato plant requires at each period of its growth. I like to get the most out of my tomato plants, so this is how I water them at each stage:
- I soak the plant’s soil whenever I plant or transplant it
- I check the plant’s soil more often during hot summer days and water it more when the top inch of soil is dry
- I limit the quantity of water I give my plants once they begin producing fruit (this reaps a better tasting and looking product)
- I hold off on watering after rainfall since nature has done the work for me
Heat & Sunlight
Yes, tomatoes need the warmth of the sun, but even they can get too much. If it has been extra hot and sunny in your garden lately, you can easily chalk-up curling leaves to our friend, the sun. One way to find out for sure if this is the cause of your tomato plant troubles is to provide your plants with some shade.
- Your potted tomato plants can be moved to a shady spot during the hottest parts of the day and returned to sunny areas once the temperatures have cooled.
- Your garden bed tomato plants can benefit from a garden shade cloth that can be placed over them during the hottest parts of the day and then removed later.
Nutrition is important for any living organism, even the humble tomato. If the soil where your plant is growing is not nutritionally balanced, you may begin to see its leaves curling. There are three basic nutritional imbalances to look for in tomato plants, and to better understand and treat this issue, let’s look at each one in detail.
Tomato plants need this chemical but it is so easy to over-distribute it. If you notice any of the following symptoms, you may have too much nitrogen in your plant’s soil:
- Recent fertilization
- Curling leaves
- Leathery leaves
- Dark green leaves
- Excessive growth of leaves
Once you have decided that these symptoms define what you are seeing in your tomato plants, you can opt to check the soil for more confirmation. If this is what your plants are facing, it is pretty simple to resolve. Here are my three tips for dealing with nitrogen:
- Do not add any more fertilizer
- Allow nature to run its course (the nitrogen should work its way out of the plant’s system)
- Do not apply a nitrogen-rich fertilizer once the plant is producing fruit
Applying a chemical to plants to prevent a pest infestation is smart, but unfortunately, it too can cause some damage. If you notice that your plants have curling leaves, malformed tomato fruit, and/or twisted leaves and stems, you may be facing herbicide damage.
The best way to deal with this type of damage is to care for it as normal and watch it grow. If its new leaves and fruits grow in a normal fashion, the plant may have healed from the damage. However, if it continues to produce abnormal leaves and fruit, you should dispose of the plant. Do not consume any fruit that may have herbicide damage.
Nutrient Deficient Soil
In the scenario where your tomato plant’s soil is lacking necessary nutrients, it will begin to show in the following ways:
- The bottom leaves curl upward
- Leaves turn yellow
Fortunately, this is an easy fix. Simply provide your plant’s soil with some extra nutrition in either of the following forms:
I like Dr. Earth Organic Fertilizer because it is designed to be used on the products you will consume. This stuff allows me to gravitate toward that free-from-the-bad-chemicals style of gardening that I long to use more of.
This is another excellent and natural way to supply your garden veggies with the nutrients they need. I like to make my own, but you can purchase premade packs from Amazon or your favorite lawn and garden shop.
Disease & Pests
Every garden faces these issues at one time or another. Sure, it’s frustrating, but fortunately, there are so many good ideas for how to prevent and treat disease and pests that we don’t have to get discouraged when they arrive on our plot of soil.
Three main diseases cause tomato leaves to curl. These diseases are brought on by poor care and/or pest infestations. If they are not dealt with quickly and properly, they will kill the tomato plant. Let’s look at a detailed analysis of symptoms and treatments for each.
This is a disease brought about by overwatering your tomato plant. When this disease strikes, you’ll not only notice curling leaves but also soggy soil and squishy, translucent leaves and stems.
The best way to treat root rot is to prevent it altogether. Learn to water your tomato plants properly, and you won’t have to deal with this disease. If, however, you are currently facing this issue, you need to work through the following steps:
- Resist the urge to water your plant
- Provide your plant with more drainage
- Prune damaged leaves
- Transplant to a new plot if possible
Curly Top Virus
If you notice that your tomato plant has curling leaves and is growing wiry at its top, you may be facing Curly Top Virus. This disease is spread by leafhopper pests and whiteflies, but it will usually stay on one plant only. The best way to treat curly top virus is to apply insecticidal soap or neem oil to the plant’s leaves.
Tomato Mosaic Virus
This is the one disease that cannot be treated. Once you have identified that your tomato plant is infected by Mosaic Virus, you need to dispose of it, or it will spread throughout your garden. Symptoms of this virus are:
- Curling leaves
- Leaves with colored spots
- Fruits that are brown on the inside
Note: These are just a sampling of the many diseases that can cause tomato leaves to curl. There are actually hundreds of plant viruses that are capable of causing this. Most of them can be prevented or treated by properly caring for your plants.
There are two common gardening procedures used to care for tomato plants that can cause them stress. These are transplanting and pruning. Most gardeners will do one or both for their tomato plants, but sometimes we forget that these common procedures are stressors for plants. While it may not be possible to avoid using these procedures on our plants, we can limit the amount of stress on the plant.
Let’s take some time now to look at both and learn more about how to limit stress while working through these procedures.
It’s easy for any plant to get shocked by being moved from one plot of soil to another. There is, however, a good method that will reduce or eliminate shock altogether. Here are the basic steps:
Harden the plant
This means that you will put the plant outside for ten days so that it can get used to the great outdoors. It is a process that requires you to set the plant outside for an hour the first day, then bring it back inside. Each day, you should increase the amount of time the plant spends outdoors.
After four or five days, it should be ready to stay outside overnight. Once ten days have passed, the plant can remain outside permanently.
Prepare a plot
Before you set your tomato plant in a garden bed, you should get its new home in order. Ensure that you select a garden plot that receives at least eight hours of full sun every day and has good water drainage. You can also add some compost to its plot for extra nutrition.
Move the Tomato Seedling
- Dig a hole that is slightly deeper than the container the seedling is currently in (if you transplant more than one tomato plant, dig holes at least 30” apart)
- Remove the plant from its current container
- Gently loosen the plant’s roots
- Place the plant into the hole and cover with dirt
- Ensure that the plant’s lower leaves are above ground level
There is a divide within the gardening world where pruning is concerned. Some gardeners believe tomato plants should not be pruned, whereas others are convinced that pruning will grow the best tomatoes. No matter which side you are on, you have to face the pros and cons of each.
Pros & Cons of Not Pruning
- More leaves to convert sunlight into energy
- No threat of shock from pruning
- Possible growth of molds and fungi from lack of airflow
- The plant may focus on growing more greenery than fruit
Pros & Cons of Pruning
- It allows more airflow
- It encourages growth in indeterminate tomato plants
- It can cause stress to the plant
- It removes the plant’s source of converting sunlight into energy
- It can stunt growth
- It can leave the plant stems vulnerable to direct sunlight
If you do decide that pruning is the best way to care for your tomato plants, then I’d like to share my best practices with you. They are:
- Do not prune determinate tomato plants
- Remove the suckers when they are still small
- Do not prune so much that your plant cannot utilize sunlight
- Prune only so much as to provide airflow to the plant
Answer: Determinate tomatoes are plants that grow to a fixed, or determined, size. They produce fruit quickly but die off quickly too.
Indeterminate tomatoes are plants that are capable of growing until the cold of winter kills them. They don’t produce fruit right away, but once they start, they will continue producing until they die off. Because they don’t stop growing until winter, their size is indeterminate.
Answer: The simple answer is yes, but this answer must come with a caveat. Coffee does not provide enough nutrition to be a primary fertilizer. It doesn’t hurt to add coffee grounds into the soil of your tomato plants, but don’t expect them to grow especially large or delicious because you do.
Answer: It is best to provide your tomato plants with slightly acidic soil somewhere between 6.0 and 7.0. You can test the pH levels of your soil with a pH tester kit and make it more acidic by adding limestone to it.
This information about tomato plants has helped my gardening so much, and I hope it has helped you too. There are complicated things about gardening, but tomatoes with curling leaves is not one of them. I’m ready to head to my garden now, and I wish you well in yours. Here’s to a great harvest this year!