Tomato plants are a favorite among home vegetable gardeners, and for a good reason. These juicy, savory-sweet fruits are not only delicious but also come with the impressive ability to pollinate themselves. Regardless of your gardening skill level, understanding tomato self-pollination will help you ensure a bountiful harvest in your own garden. In this article, we’ll explore this fascinating process, so you can become a tomato-growing pro!
My brother and I were joking the other day about building a sort of closet around my tomato plants this year, because my biggest tomato-growing challenge in the yard is an abundance of tomato-loving squirrels and chipmunks.
He said he had a plan using double-layered, offset chicken wire, and I scoffed, joking that it would have to be reinforced window screen to keep those wily critters out. He replied, but what about the bees — are tomatoes self-pollinating?
Ding ding ding! And the idea — and need — for this article was born.
Tomatoes are, indeed, self-pollinating. And while bees and other pollinators can help things along, tomato flowers are what’s known as perfect flowers. That is, every flower contains all of the necessary parts for reproduction, including pollen, pistil, stamen, and ovary.
In fact, all nightshade vegetables are self-pollinating: Tomatoes, peppers/chile peppers, eggplant, and okra. Potatoes are also self-pollinating, but don’t rely on that process to produce tubers. This can be useful knowledge to have when planning your garden.
For example, I do a lot of container gardening, and my tomatoes and peppers usually sit in an area where pollinators don’t frequent. And that’s okay. But it’s important that pollinator-dependent crops, such as squash and other cucurbits, do have access to pollinators.
But, in terms of armoring up my tomato plants, I don’t have to worry about pollinator-led fruit production because nature’s already solved that issue.
While the science of self-pollination is fascinating, I have a simpler goal with this article: If your tomato fruit production is lagging, there’s a quick and easy thing you can do to help the process along.
Let’s take a closer look at how tomatoes self-pollinate.
All About Tomato Pollination
Tomatoes (Solanum lycopersicum) are not only able to self-pollinate, they are, in fact, predominantly self-pollinating plants.
This means that the pollen from a flower’s male reproductive organ is transferred to its own female reproductive organ to fertilize the ovules and produce fruit, all in the same flower. Here is an overview of the process:
As mentioned above tomato flowers are perfect flowers, meaning they contain both male and female reproductive organs. The male part, called the stamen, consists of a filament and an anther that produces pollen. The female part, called the pistil, has a stigma and ovary containing ovules.
In tomato flowers, the stamen forms a cone-shaped structure around the pistil, which creates a self-contained space for the pollination process to occur. When the flower is mature, the anther releases pollen grains.
Due to the close proximity of the male and female organs within the flower, the pollen easily reaches the stigma, resulting in self-pollination.
Vibration and pollen release
The release of pollen from the stamen can be facilitated by wind, insects, or even just vibrations caused by touch. Tomato flowers are particularly sensitive to vibrations, which help to shake the pollen loose from the stamen and onto the stigma.
In nature, bees may visit tomato flowers and contribute to this process, but the vast majority of pollination still occurs without their assistance.
And actually, in the case of pollinators, it’s the vibrations from the bees landing on and crawling around the flowers that result in pollination, rather than them depositing pollen themselves.
Fertilization and fruit formation
Once the pollen grains land on the stigma, they germinate and form pollen tubes that grow down the pistil and into the ovary. The sperm cells in the pollen grains then fertilize the ovules, leading to the development of seeds and the surrounding tomato fruit.
It is important to note that, while self-pollination is the norm for tomatoes, cross-pollination among plants of different varieties can still occur. This is particularly true for heirloom varieties, which may have more open flower structures that are accessible to pollinators like bees.
The average home gardener does not have to worry about cross-pollination, because the current season’s tomatoes will always be true to type, regardless of which plant the pollen came from.
Cross-pollination only becomes an issue for seed savers, as it will impact the fruit of next year’s plants.
How to Hand-Pollinate Tomatoes
Unlike hand-pollinating squash plants, which requires a little effort (although still simple), giving your tomato plants a pollination assist is as easy as grasping a tomato truss that contains fully-formed flowers and giving it a brief and gentle shake.
That simple motion will loosen pollen grains from the stamen and set them afloat within to land on the pistil.
Even though Mother Nature is quite efficient in ensuring that her delicious plants propagate, it never hurts to go through your plants once a week and give the trusses a little shake. Especially the trusses hidden within the plant.
Frequently Asked Questions about Tomato Self-Pollination
Do I have to hand-pollinate my tomato plants?
Generally, tomato plants self-pollinate without the need for human intervention. However, in some cases, such as when growing tomatoes indoors or in areas with low pollinator activity, you may choose to hand-pollinate to increase fruit set.
When I grow tomatoes in containers on my deck, I make it a point to hand-pollinate throughout the season with a little shake here and there, because if the wind changes direction and comes from the north or east instead of the west — as happens when summer storms swirl around the region — my plants are protected from the wind by structures on the deck.
Do I need to plant multiple tomato plants for successful pollination?
No, since tomato plants are fully self-pollinating, you do not need to plant multiple plants for successful pollination. However, planting multiple plants can provide a more abundant harvest and allow you to enjoy different tomato varieties.
Don’t forget that all nightshades are self-pollinators, including peppers and eggplants, and can be planted singularly.
Why are my tomato flowers falling off without setting fruit?
This is a common issue known as blossom drop. It can be caused by several factors, including temperature fluctuations, poor pollination, excessive nitrogen in the soil, or insufficient water. To mitigate this issue, ensure your plants receive proper care, such as consistent watering, balanced fertilization, and exposure to adequate sunlight. You can also try hand-pollinating to improve fruit set.
Can self-pollinating tomato plants produce fruit without any insects or wind?
Yes, tomato plants can produce fruit without insects or wind, as their flower structure promotes self-pollination. However, vibrations, whether from wind or pollinators landing on and crawling amongst the branches, can still improve the chances of successful pollination by shaking pollen loose from the anthers.
In the absence of these natural aids — such as in a closed greenhouse environment — you should manually shake or tap the branches to encourage pollen release.
For the record, window screen isn’t a great solution for protecting tomatoes because squirrels will just gnaw right through — nothing so flimsy will stand between them and an heirloom Cherokee Purple! — and I would worry that the screens, which can block up to 30% of sunlight, would cause fruit production to suffer.
But if your garden is small and you only have space for one tomato, no worries! Pollination won’t be a problem. Happy tomato gardening!