Last Updated: April 13, 2023
Tomatoes take a long time to grow. Naturally, along the journey from seed to harvest, there are bound to be some issues. From pests to disease and everything in between, we have to be prepared to roll with the punches.
However, if your tomato plants seem to be dying, don’t wait around – take action quickly. In this article, I’ll share the most common reasons for tomato plants dying, and how to save them before it’s too late!
Poor Watering Habits
One of the easiest ways to kill your tomatoes is to water them improperly. One of the first things to learn about growing is watering tomato plants the right way.
Too much water can lead to unhealthy or rotting roots, as well as wilting leaves and sometimes even disease. Poor drainage is the most common reason for over-watering tomatoes, so be sure your soil drains well. Potted plants should have plenty of holes in the bottom, or better yet, try growing in grow bags instead.
Too little water can definitely make you think your tomato plant is dying. A dehydrated tomato will show severely wilting leaves. While it is a simple fix (just water the plants), under-watering can lead to two other, major issues. Cracked tomatoes and blossom end rot are caused by letting a tomato plant dry out, and then watering it deeply. The influx of water into the dehydrated plant causes swelling of the fruits, causing them to split.
So, how should you water tomato plants? The answer is simple: water on a regular schedule.
Well, I guess it isn’t quite that simple. Tomato plants are healthiest when they are consistently hydrated throughout. This means keeping the soil moist, but not overly saturated, at all times.
If your soil drains well, the easiest solution is to set up an automated watering system like a drip irrigation line. These relatively inexpensive systems require some setup, but after that they are set it and forget it.
If your soil doesn’t drain well, then you should work on improving your soil (or grow tomatoes in containers instead). To improve garden soil, amend it with compost at least once a year. This will improve both the nutrient levels and the soil structure to hold the right amount of moisture.
Another reason people think their tomato plants are dying are the signs of heat stress. In mid-summer, when tomatoes are just starting to produce fruits, temperatures can often soar.
Though tomatoes like warm weather, when a plant experiences temperatures above 90°F (32°C) or so, they will become stressed. The symptoms are obvious: drooping leaves and often leaf curling.
If your tomatoes don’t have adequate support, such as a trellis or cage, then the intense heat may cause them to slump over. This is obviously concerning if you don’t understand the root cause.
Note: If you are moving your tomato seedlings from indoors to outdoors, always harden them off to the direct sun. Failing to do this will lead to wilting, sun scald, and potential die back.
If you are in a heat wave, the easiest way to help your tomatoes is to provide some shade. Air temperatures under a tree can be up to 25°F cooler than in direct sunlight!
For containers, move your tomatoes to a location with afternoon shade (such as under a tree or on the East side of a building. The afternoon is usually the hottest part of the day, so allow them to receive morning sun, with afternoon shade.
For in-ground plants, use a 40-50% shade cloth to provide temporary shade. Again, you’ll want the tomatoes to have morning sunshine with shade for a few hours in the afternoon.
All tomatoes should be pruned in one way or another! If you aren’t pruning your tomatoes at all, chances are it is having a negative impact on their overall health.
Improper pruning can lead to poor airflow and ultimately disease. Pruning may feel counter-intuitive (why remove leaves if they are helping photosynthesis?), but it actually helps tomato plants.
Indeterminate varieties require the most pruning, as you will remove the suckers and excess dense foliage. Most determinates will keep their suckers, but you still need to prune away some of the large fan leaves during the summer.
Learn more about pruning tomatoes properly here.
Up until now, we’ve covered symptoms that can resemble a dying tomato plant. Now, we’ll discuss disease, which can actually be a death sentence for infected tomato plants.
Tip: Identifying plant diseases is hard. Try this useful ID tool from Cornell to home in on what may be affecting your tomato plants.
Bacterial and Fungal Infections
Some of the most important tomato diseases are a result of bacteria or fungal infections. Among the most common are:
- Early blight
- Bacterial wilt
- Damping off
- Fusarium wilt
- Septoria leaf spot
- Verticillium wilt
While these diseases can sometimes be controlled in the garden, it is often best to remove any affected plants. Fungicide products can be helpful in decreasing the spread of some fungal diseases, but not all.
Thankfully, through cross-breeding, we have many disease-resistant tomato varieties available to grow at home. I highly recommend researching which diseases are common in your area and finding varieties resistant to them.
Many viruses can infect tomato plants. Some of the most prevalent are introduced to the plant by insects. As a result, one of the best preventative measures against disease is to actually control pests.
Common tomato viruses:
- Tobacco mosaic virus
- Tobacco etch
- Potato virus Y
- Curly top
- Cucumber mosaic virus
Once a plant is infected with a virus, there is very little you can do to stop the spread. Removing and burning any of the foliage impacted is step one. Then, you should monitor for a resurgence. To be safe, any tomato plant with a virus should be tossed and never composted.
Tips to Reduce Disease in Tomatoes
Having disease impact your otherwise healthy plants can be disheartening and frustrating. Instead of having a reactive approach, be proactive next season. Here are my top tips for preventing tomato disease:
- Choose disease-resistant varieties
- Practice good hygiene before and after gardening
- Bottom prune plants to avoid soil-borne disease
- Keep pests under control
- Avoid smoking in the garden
Like I said in the previous section, pests don’t just directly damage tomato plants. They can also bring in diseases which can wreak havoc on your garden. If your tomatoes are dying from disease, you may actually want to treat it as a pest issue.
Tomatoes aren’t just tasty to humans. Chipmunks, birds, squirrels, and deer can all stop by to have a taste of your delicious nightshades.
The best way of preventing these critters from feasting on your hard work is to use physical barriers. A low fence can keep out many, but if birds or deer are your problem, you may need to use netting or a taller fence.
Insect pests are the worst. They are hard to see, can vector diseases, and are sometime nocturnal. Aphids, thrips, white flies, caterpillars, leafhoppers, and so many more “bad” insects can feed on your tomatoes.
Tips for reducing pests (in the proper order):
- Fence in your garden (above and below ground)
- Plant companion flowers
- Use insect netting early in the season
- Spray insecticidal soap (as a last resort)
The first step is identifying your insect pest. You may need to use a magnifying glass, look underneath leaves, or inspect your plants at night.
Thankfully, many insects also have natural enemies: predators that will feast on the pest. My favorite pest management method is to attract these predators with flowers and other beneficial plants.
Some tomatoes are perennial in their natural environment. This means they can live for years in the proper climate. However, here in New England, we grow our tomatoes as annuals.
This means that our plants will die to the cold weather that comes in winter. As the temperatures drop, leaves will begin to turn yellow, productivity will drop, and eventually the plants will die to frost.
Death from frost is to be expected, however many gardeners have volunteer tomatoes come back every year from fallen fruits.
As tomato growers, we should learn to have some tolerance for “things-not-going-according-to-plan.” One tomato plant dying doesn’t mean you’re a bad gardener. Instead, use it as a learning experience and do your best to prevent it next season!