It is very disappointing when a tomato plant that started out healthy and strong begins to wilt halfway through the season, and it can be extra frustrating if you don’t know why your tomato plants are wilting.
It’s important to understand that the rigidity of your tomato plant is primarily dependent on the amount of water pressure available in the cells of the leaves and stems, called turgor, which can be inhibited by several different factors.
Some issues are more serious than others, but all should be addressed as soon as they are noticed in order to save your tomato and prevent the spread of disease to other plants in your garden.
In a nutshell, your tomato plants may begin to wilt or drop due to a lack of water, the presence of fungal or viral infections, pests feeding on your plant, or because they are planted too close to a walnut tree.
These reasons are all quite different from each other and require separate courses of action to remedy the problem.
Read on to better understand how these situations arise, why they cause tomato leaves to wilt and dies, and how you can save your wilted tomato plants or prevent them from arising again.
5 Reasons Why Your Tomato Plants Are Wilting And Dying How To Save Them
Wilting in tomato plants has many causes, and It is often difficult to distinguish these diseases that can cause tomato leaves to wilt or droop.
Here is a deeper dive into each of the five possible reasons for wilting tomatoes, how to identify them, and what you need to do to fix them:
1: Tomato Plants Wilt Due to Too little water
Excessive loss of water can cause drooping and wilted leaves on tomato plants. Your tomato plants will begin to wilt if they do not have sufficient water pressure to keep themselves erect.
This is a common cause of wilting in many non-woody plants including tomatoes, which are dependent on something called turgor in their cells to keep the plant upright.
Your plants will lose water throughout the day (in a process called transpiration) and if their roots are not provided with enough water to make up for that loss, the plant will begin to droop as cells become depleted of water and turgor.
Tomatoes that are dehydrated will show signs of wilting on lower and upper branches and leaves, and they may begin to wither.
Gently bend a disposable branch and if it snaps like a dry branch then it is severely dehydrated, tomato branches should be flexible and slightly bendy.
Stick your fingers into the soil a couple knuckles deep, and if it is dry at this level then dehydration is almost certainly the problem.
Solutions and prevention:
Tomatoes need approximately one inch of water per week, and they prefer a deep soaking less frequently over little bits of water everyday.
Depending on your climate, this will probably mean a thorough watering twice a week or so, but should be adjusted according to heat waves or rain events.
As long as it hasn’t been over a week of severe wilting, your tomato plants should make a full recovery when given a good deep drink. If plants are left to become extremely dehydrated they can die, so make sure to stay on top of the issue.
To prevent wilting from too little water from occurring, keep your tomatoes on a regular watering schedule and set reminders on your phone or calendar so you don’t forget.
2: Tomatoes Wilting Due to Fungal diseases
Verticillium wilt and Fusarium wilt are two different fungi that will cause your tomatoes to wilt once infected.
The spores of these fungi can survive in the soil over winter or on plant debris that is left out in the field, and will enter your next seasons’ plants through their root system.
Both diseases will cause wilting by growing up inside the xylem of the plant and blocking the transport of water and nutrients, thus causing leaves and stems to lose their turgor.
Tomato plants and other vegetables in the nightshade family can be affected at any stage of growth, although it is thought that in Northern climates Verticillium wilt affects plants later in the season when soil temperatures are at least 70- 75℉. Fusarium wilt is more prevalent in Southern regions as it prefers temperatures of 80 – 90℉.
To confirm it is a fungal infection inside the plant, slice away a vertical section at the base of the stem and check for the presence of a brown substance inside.
With Fusarium wilt sometimes only one side of the plant will wilt and yellow, or just the lower branches.
Verticillium wilt starts affecting lower branches at first, and they may appear to recover at night only to wilt again during the daytime.
Solutions and prevention:
There is no cure for either of these fungal infections, and infected plants should be removed and thrown away immediately to prevent further spread- do not add to your compost pile!
Take many preventative measures to keep these fungi out of your garden, as Fusarium wilt can survive in the soil for up to 10 years!
Always remove plant debris at the end of the season, rotate crops in the nightshade family every season, solarize soil with tarps in the spring, buy resistant tomato varieties, and grow non-resistant varieties in pots to be sure these aggressive fungi have a very low chance of establishing themselves in your soil.
3: Viral infection Can Causes Wilting In Tomato Plants
Tomato Spotted Wilt Virus (TSWV) will, as the name might suggest, cause your tomato plants to wilt and yellow.
It is transmitted by thrips, a common pest for tomato plants, which will pass the virus from their gut into the plant tissue of your tomatoes when they are feeding on them.
Symptoms of TSWV include stunted or lopsided growth, brown flecks on the leaves, and raised circular areas and spotting on the fruits. Wilting usually occurs at the growing tips and new growth rather than on older, lower branches.
The only way to 100% confirm the presence of TSWV is to take a sample and send it into a local agricultural university lab (some will also ID infections via emailed photos!).
Solutions and prevention:
Unfortunately, like the fungal infections, there is no cure for plants with TSWV. Infected plants should be removed ASAP and burnt or thrown out, and nearby weeds or plant debris should also be removed.
Purchase tomato varieties that are resistant to TSWV, and other preventative measures are focused on managing thrip populations in your garden, since they are the main vector for the virus.
Salicylic acid sprays can be used on tomatoes to ward off thrips, which won’t like to feed on plants with it on their surface.
Sticky yellow and blue cards can be bought at plant centres or online and are particularly effective in greenhouses for catching thrips amongst other pests.
4: Pests Can Cause Your Tomato Plant To Wilt
Stalk borers and thrips (see above) can cause your tomato plant to wilt after they enter or feed from it.
Stalk borers are small caterpillars- which turn into moths- that will bore a hole at the base of your tomato plant in the spring and tunnel into the main stem, impeding the flow of nutrients and water which causes wilting.
There may be signs of a boring caterpillar such as excrement around the main bore hole somewhere near the bottom of the plant, or little holes that are used by the insect for breathing as it moves up the stem.
These will often be quite difficult to spot, so try to eliminate other possibilities and get to this cause through process of elimination.
Solutions and prevention:
If signs of the pest are noticed before extensive wilting has taken place, it is possible to remove this pest through a somewhat risky surgery.
If you have located a bore hole and/or insect excrement, you can make a vertical incision on the stem and try to remove the caterpillar with tweezers.
After removal, the plant must be patched up with horticultural tape and be carefully monitored, as this kind of opening can weaken the plant and create an entrance for other pests and disease.
If the plant is already severely wilted, the damage may already be done and the plant should be removed.
Mulching plants in the spring can help create an access barrier to the stalk borer, and cutting away tall grass or overgrown weedy paths and edges to your garden will reduce its hiding spots.
5: Close proximity to walnut trees
An organic compound called juglone is excreted from all parts of the black walnut tree, and is toxic to all members of the tomato family, amongst other crops.
As well as wilting, tomato plants affected by juglone may yellow, wither, and eventually die.
Since this compound is found in leaves and branches, even foliage or debris from dead trees can leach it into the soil and damage tomato plants.
Plants are most affected when they are in the flow path or drip line of the walnut tree where run-off will transport juglone directly into their roots.
Symptoms of tomatoes that are uptaking juglone closely resemble those of Fusarium and Verticillium wilt, with wilting and yellowing leaves.
The stem of your tomato plants may also develop brown, vertical streaks and growth will become stunted. The best way to identify this issue is to look around for any source of juglone in the area.
Solutions and prevention:
If you have just realized shortly after transplanting your tomatoes that they are less than 80 feet away from a walnut tree or tree material, quickly dig it back up and transplant it in a suitable spot further away or into a pot.
If plants have already begun to wilt and show serious symptoms, it is too late to save them and they should be removed and destroyed. Black walnut branches, leaves, or fruits should never be used as mulch or put into a compost pile.
Frequently Asked Questions
I just transplanted my tomatoes into my garden and they are already wilting! What’s the problem?
Newly transplanted tomatoes may temporarily wilt for the first two or three days after transplanting due to shock.
If you started out with healthy seedlings that were watered well before transplanting, and there is no walnut tree nearby, this is likely the case and there is no need for concern.
Make sure to always harden off seedlings before transplanting to reduce these effects. If a week has passed and your plants are still wilted, you will need to investigate other causes.
I have been watering my plants lots and they are still wilting, what am I doing wrong?
Overwatering plants can also create a wilting effect, as soggy soil can create root rot which restricts the ability of the roots to deliver water and nutrition to the rest of the plant, and also blocks their oxygen uptake.
Underwatering is a much more likely reason for wilting than overwatering, but you should keep this in mind and make sure your soil surface dries out between waterings. If you don’t believe you are overwatering, check for symptoms of stem borers or disease.
Do potted tomatoes wilt more?
Potted tomatoes are generally safer from the stem borer and won’t be affected by the juglone excreted by walnut trees, but are more likely to dry out quickly.
This is especially true for porous, clay pots but applies to all plants grown in above-ground containers, which are heated up by the sun during the day and increase soil water evaporation.
As long as you adjust your watering schedule accordingly for potted tomatoes, there is no reason they should wilt more than those in the ground.
Can you buy wilt-resistant tomatoes?
Unfortunately no, not entirely. You can buy tomatoes that are resistant to Verticillium and Fusarium wilt and Tomato Spotted Wilt Virus, which decrease the likelihood of disease causing wilting in your tomatoes and will save you stress later in the season.
But underwatering and pest issues like the stem borer won’t be particularly affected by variety and can still cause wilting.
Amber Noyes was born and raised in a suburban California town, San Mateo. She holds a master’s degree in horticulture from the University of California as well as a BS in Biology from the University of San Francisco. With experience working on an organic farm, water conservation research, farmers’ markets, and plant nursery, she understands what makes plants thrive and how we can better understand the connection between microclimate and plant health. When she’s not on the land, Amber loves informing people of new ideas/things related to gardening, especially organic gardening, houseplants, and growing plants in a small space.