It is frustrating to see your tomato plants flowering without producing any fruit. Luckily, there are some steps you can take to identify the problem and save your harvest.
So, why are your tomato plants flowering but not producing fruit? A lack of pollination due to extreme temperature or humidity is a common cause of tomato plants flowering without producing fruit. Other environmental factors that can delay fruit production include water, light, nutrient deficiencies, pests, and diseases.
It’s important to remember that it takes over a month to go from the appearance of a flower to a ripe tomato. So, be patient! However, if you aren’t seeing any fruit starting from flowers on your tomato plant, then it is time to do some detective work to find the source of the problem.
Let’s start off with pollination for tomato plants: how it works, what can prevent it, and how you can take matters into your own hands.
Tomato Plant Pollination
If your tomato plant has flowers but no fruit, a lack of pollination is the most likely cause. Before we can understand a lack of pollination, we need to know how pollination works for tomato plants.
How Does Tomato Plant Pollination Work?
Tomato plant flowers are self-pollinating. This means that each flower contains both a male part and a female part. It is a myth that 2 tomato plants are needed to get fruit; one plant can pollinate itself.
However, self-pollination does not mean automatic pollination. Tomato flowers do contain both a male and a female part, but they still need help with pollination.
Usually, a bee provides this help to tomato flowers. When bees visit flowers in search of nectar, they hover near the flower. As their wings vibrate, the bees cause the flower itself to vibrate.
This, in turn, causes the male part of the flower to release pollen onto the female part of the flower. If conditions are right, then the female part of the flower will be properly pollinated.
The flower will then form fruit, which should develop into a healthy tomato if there is enough water, nutrients, and sunlight.
Obviously, this process does not always work so easily. Let’s look at some of the factors that can prevent pollination of tomato plant flowers.
What Factors Can Prevent Tomato Plant Pollination?
By far the biggest factor that prevents pollination is a lack of bees. Bee populations have been declining in many parts of the U.S. and the world in general.
Part of this is due to diseases, and part of it is due to pesticides and other chemicals used in farming and gardening.
If you don’t see many bees in your garden, consider going pesticide-free to give the bees a chance to recover. Planting flowers to attract bees is also a good idea.
You can even ask your neighbors to do the same to create a larger area where the bees can live and work. Of course beekeeping is another option if you also want honey every year!
Another factor that prevents tomato plant pollination is extreme temperature or humidity. Pollination will often fail if daytime temperatures go far above 85 degrees Fahrenheit, or if nighttime temperatures go far below 55 degrees Fahrenheit.
So, pollination may be delayed during a heat wave in the summer, or during a cold spell in an area with a short growing season.
If humidity levels are too high, then the male part of the flower will not be able to release the pollen onto the female part of the flower. If humidity levels are too low, then the pollen released by the male part will not stick to the female part.
Excessive wind can also contribute to tomato flowers drying out. For more information, see this article from the Iowa State University Extension on how temperature and wind can affect tomato flower pollination.
There is not much you can do about the weather conditions to help your plants. However, you can certainly try to help with pollination, especially if there are not enough bees to do the job.
How Can I Hand Pollinate My Tomato Flowers?
Maybe the bee population in your garden is not enough to allow for pollination. Maybe you want to give your plants an extra chance to pollinate during hot or cold weather. Here is how to hand pollinate your tomato flowers.
First, choose your tool for hand pollination. One of the best is an electric toothbrush. The vibration of the toothbrush will simulate the vibration caused by a bee’s wings.
You can also use a tuning fork (strike it against something hard and then use it while it is vibrating).
In addition, you can use a toothpick, pencil, or stick to move the flowers out of place, causing them to vibrate when they spring back to their original position.
Second, choose the time that you will hand pollinate. In the middle of a heat wave, you will want to use hand pollination in the morning or late evening, when temperatures are cooler. This will give the pollen a better chance to work.
If you are getting unseasonably cold weather, then look at the weather forecast and try hand pollination at the warmest time of the day. If you are worried about cold damage to your tomato plants, check out my article on how to protect your tomato plants from cold and frost.
The more often you use hand pollination, the better the chance it has of working, but choosing your time wisely will further increase your chances of success.
Be sure to visit every flower you can see, and go around each tomato plant to make sure you don’t miss any.
For more information, check out my article on hand pollination for tomato plants.
Another possible cause of a lack of fruiting on tomato plants is a nutrient imbalance. There are a few different possibilities and causes. Let’s start with excessive nitrogen.
Many gardeners know that nitrogen is a necessary nutrient for plant growth. However, many do not know that too much nitrogen can actually prevent flowering or fruiting of plants.
Nitrogen is the nutrient that helps plants to produce lush, green foliage. This is helpful when the plant is trying to grow taller and store energy in its roots.
However, it is eventually time to put this extra energy to use by producing flowers and fruit. When a plant has too much nitrogen, it gets the signal to continue producing green growth, rather than flowers and fruit.
Using manure or a fertilizer heavy in nitrogen can cause excessive nitrogen levels in your soil. If the nitrogen levels are high enough, you may even see some plants that fail to flower at all. For more information, check out my article on over fertilizing plants and my article on low-nitrogen fertilizers.
The solution: be careful when fertilizing your garden, and be sure to provide other nutrients, such as phosphorus, potassium, calcium, iron, and magnesium for your plants.
Often, a good compost mix will provide the nutrients that your tomato plants need to produce fruit. However, there are some cases where you can still experience nutrient deficiencies.
Lack of Nutrients
A lack of nutrients can prevent tomato plants from producing fruit or even flowers. A nutrient deficiency will often display symptoms such as yellow leaves on a plant. For more information, check out my article on nutrient deficiencies in plants.
Potassium, for example, is necessary for plants to move water through their tissues. Even if you have plenty of a given nutrient in your soil, your plants can still experience nutrient deficiencies if the soil pH is incorrect.
For each nutrient, there is an ideal pH range where it is available in the soil. Outside of this ideal pH range, the nutrient becomes less available for plants to absorb through their roots.
For more information, check out this article from Research Gate on nutrient availability depending on soil pH.
If you suspect that your soil pH is outside of the ideal range (for tomatoes, 6.0 to 7.0, or slightly acidic) the best way to find out is to do a soil test.
You can buy a soil test kit online or at a garden center to do it yourself. You can also send a soil sample to your local agricultural extension for more detailed testing. For more information, check out my article on soil testing.
Lack of Sunlight
Remember that tomato plants need 6 to 8 hours of full sunlight every day in order to develop properly. Without this sunlight, tomato production can be delayed, or it might never happen at all.
Transplanting mature tomato plants is risky, so unfortunately, all you can do is to choose a sunny spot for planting next year’s crop.
Too much or too little water can also put stress on your plants, causing them to drop flowers or fruit and preventing fruit from forming.
If you over water your plants, the roots may rot if the soil stays wet for too long. This is more likely when the weather is cool, damp, and calm (no wind).
Eventually, it may look like your tomato plants are drying out. However, the truth is that they do not have enough roots left to absorb water from the soil. For more information, check out my article on over watering your plants.
The best test is to feel the soil with your hands, down to a depth of a few inches. If it feels dry, go ahead and water your plants. Just be sure to avoid watering before a big rainstorm.
If you find that your tomato plants look dry and the soil is always dry, consider a deep watering once in the morning. That way, the water gets a chance to soak into the soil before the sun gets higher and temperatures rise to evaporate the water.
For more information, check out my article on how to treat dry soil.
Common garden pests, such as aphids or tomato hornworms, can also cause stress to your plants. In severe cases, fruit may fail to develop, or it may drop off. You may even see the flowers dropping off the plant.
In cases of severe aphid infestation, you may need to remove and destroy infected plants to protect the rest. Don’t put these plants in your compost pile, since you may end up with the same problem throughout your garden the next year!
For more information, check out my article on how to get rid of aphids.
There are many tomato diseases to worry about, and they are too numerous to list them all here. The best defense against disease is preventing them from happening in the first place.
Choose disease-resistant tomato plant varieties. Also, use crop rotation in your garden. This means that you should not plant the same crop in the same place every year. Rather, get on a 2, 3, or 4 year crop rotation schedule to prevent the chance of diseases and nutrient deficiencies in your soil.
Hopefully, this article gave you an idea of why your tomato plants are flowering without producing fruit, and what you can do about it. Pollination is the first place to look, and if that is the problem, then you have some work ahead of you!
If this article was helpful, or if you have questions or advice of your own, please leave a comment below.