Do Tomatoes Need to Be Pollinated? What to Know

Pollination is the transfer of pollen grains from the male part of the flower called the stamen to the female part known as the pistil. Flowers can be male, female, or complete. A tomato plant has a complete flower. This means that it has both male and female parts within the same flower.

Like any other plant, tomatoes need to be pollinated in order to reproduce. The tomato plant has an advantage over other plants since it is self-pollinating. Their flowers have both male and female parts. This simply means that even if you grow a single tomato plant, it will be able to produce fruits.

However, to literally dislodge the pollen and transfer it to the stigma, the plant requires buzz, wind, or human pollinators. Lack of these pollinating agents may result in tomato flowers not setting fruits.

Do tomatoes need to be pollinated?

In spite of being self-pollinating, the tomato plant requires pollinators to aid the whole process. The pollen has to be detached from the anthers and transferred to the stigma for fertilization to take place. Some of the common aids of pollination include:

1. Buzz pollination

Buzz pollination occurs when pollinating insects like bees, wasps, and butterflies and small birds like hummingbird visits the bloom. They land on the flowers to retrieve pollen or nectar, in the process, they help to dislodge the pollen from the anthers and transfer it to the stigma for fertilization to take place.

Bumble bees are more effective as compared to honey bees and other buzz pollinators. The vibration that results from their flight muscles helps to literally detach the pollen grains from the anthers before transferring them to the stigma.

Bumble bees are also larger in size as compared to honey bees. This allows them to carry more pollen grains on their bodies. Before bee pollinators were introduced in the greenhouse, gardeners were forced to rely on manual hand pollination which proved to be labor and cost-intensive.

2. Hand pollination

Hand pollination involves human being aiding in the process of dislodging the pollen from the stamen and transferring it to the pistil. There are several hand methods that you can use in aiding the process of pollination. You can gently shake the stem of the plant when it is in bloom to transfer the pollen.

Using other tools like an art brush, cotton ball or an electric toothbrush can also help to collect the pollen grains from the male part of the flower and transfer it to the female part. However, you are supposed to be careful to prevent cross-pollination if there is more than one tomato variety in your garden

The tools are supposed to be cleaned thoroughly to remove all the pollen grains before attending to a different tomato variety within your garden.

3. Wind pollination

Wind can also play a role in the process of transferring the pollen. It occurs when the wind blows across your plants. The wind carries along the pollen and deposits to the female parts of the flower. Wind pollination can also occur when animal and human beings brush against the flowers.

How to tell if tomato flower is pollinated

It takes approximately 1 to 4 days after pollination to observe any noticeable changes in the tomato plant. However, there are some telltale signs you can easily watch for.

Have you noticed that there are a lot of pollinators flying around your garden? If yes, then it is a good sign that your plants are pollinated. Bumble bees normally bite on the flowers after every visit. A single set of bite marks may be an indication that pollination has already taken place.

After pollination, the stem behind the flower will start to swell and you can easily feel a tiny BB-sized tomato fruit at the end of the flower.

The appearance of the stem can also tell if pollination has taken place or not. If the stem is yellowing, it means that the bloom is dying off without forming the fruit. On the other hand, if the stem near the bloom remains green and begins to get larger, then the tomato fruit is developing

Do bees pollinate tomatoes?

The answer is yes, bees do pollinate tomatoes. Bumble bees together with other insects like butterflies and small birds are very important in aiding the process of pollination in plants all over the world.

When it comes to tomato reproduction, they are self-pollinating. This means that they can transfer pollen from their own stamen to the stigma. However, they require other pollinators like the bumble bees to dislodge the pollen grain from the anthers and distribute it to the stigma for fertilization.

The anthers on the tomato flowers only release the pollen grains when vibrated. The vibration can be achieved with the help of bumble bees through buzz pollination. The bumble bees place their body next to the anthers and vibrate their flight muscles. The vibration literally dislodges the pollen from the anthers.

Rather than buying vibrating tools and employing manpower to help pollinate tomatoes in your greenhouse, you can simply provide small entrances to allow bumble bees to do the job at no cost. Tomatoes pollinated by bumble bees tend to produce more as compared to those that are hand pollinated. 

Why tomato flowers are not setting fruits despite being pollinated

Once the flowers are pollinated, they should be able to produce the fruits. However, it can be quite unfortunate to realize that your tomato plants are not setting the fruits. This scenario can be attributed to various conditions that include:

1. Excess heat

Tomatoes like it hot but not too hot. In hotter climates, high temperatures can wreak havoc in your garden. Temperatures that are above 85 degrees Fahrenheit during the day and below 75 Fahrenheit at night can be detrimental. Extreme temperatures can turn the pollen grains sterile.

2. Inadequate fertilizer

Soil fertility plays a very big role in the overall health and productivity of tomato plants. Tomatoes require adequate potassium, especially during flowering. Potassium enhances flower production in plants. Its deficiency can result in flowers not setting fruits or poor production.

3. Excess shade

It is important to keep your plants in the shade during the hottest hours of the day. However, too much shade can also decrease productivity. Tomato plants require at least 8 hours of direct sunlight in order to produce optimally. Utilizing the morning and evening sunlight can help to increase production.

4. Too much nitrogen

Tomato plants are heavy feeders and you should apply a balanced fertilizer after every two weeks. However, you are supposed to go easy on nitrogen and increase phosphorus and potassium during the flowering stage. Excess nitrogen causes the plant to grow more foliage at the expense of flowers and fruits.

How to pollinate tomatoes manually

To be sure that your tomato plants are pollinated, you can mimic the conditions of either wind or buzzing insects to transfer the pollen grains from the anthers to the stigma. The following methods can help to aid pollination:

1. Shaking the plant gently

Tomato plants may only be requiring a gentle shake to dislodge the pollen grains from the male part of the flower and transfer it to the stigma. Alternatively, you can gently and rapidly tap at the top of each flower with the help of your fingers.

2. Using an art brush

When your tomato plants are flowering, an art brush is among the important tools you are supposed to have at hand. It helps in pollinating the plants by gathering and distributing the pollen grains from one flower to the other in a manner that is similar to insect pollinators.

Be sure to use a brush with natural bristle. Pollen grains cling better on the natural bristles unlike plastic ones. It is simply done by rubbing the brush on the inside of the petals along the pistil and transferring it to the stigma.

3. Using cotton swabs

Those cotton swabs that are idling in your house can also be used as a tool in aiding pollination. You simply dab it on the stamen and distribute the collected pollen to the stigma. Cotton swabs can also be used to distribute already collected pollen.

4. Using an electric toothbrush

An electric or battery-operated toothbrush can also be the easiest and most effective method of distributing the pollen grains in your garden. The vibrating bristles mimic the buzz pollination and are effective in dislodging the pollen from the anthers.

Final Thoughts

The tomato plant has both male and female parts within the same flower. This means that it is self-pollinating. Pollination can occur within the same plant. However, to aid the process of pollination, the plant requires the buzz of insects and animals, wind, or human beings. The pollen requires to dislodge literally from the stamen in order to access the pistil for fertilization to take place.

References

Tomato Breeding Program – UF/IFAS Plant Breeding Program

Tomato Production – Pennsylvania State University

Pollination – University of Arizona                    

Problems with Pollination in High Tunnel Tomatoes – University of Maryland