Weeks have gone by and your tomatoes still aren’t producing fruit? Or only here and there? Their small yellow flowers simply drop off without leaving behind the tiny green fruit that is the sign of successful fruit set?
These are all symptoms of inefficient pollination. And sometimes the easiest solution is to pollinate them yourself… with an electric toothbrush!
You don’t even have to touch the face of the flower: just place the brush behind the flower and turn it on. The vibration releases the flower’s pollen and causes it to fall onto the pistil, fertilizing the flower… and giving you fruit a few weeks later.
The tomato is not like most plants, with an open flower that almost any insect can pollinate. The pistil (the receptive female part) is enclosed in a tube formed of stamens fused together. Most insect pollinators, such as honeybees, hoverflies and butterflies, can’t penetrate the flower in order to pollinate it. Instead, it self-pollinates… sort of. You see, the tomato flower still needs a helping hand.
It must be shaken for the pollen to be released and fall on the pistil. It’s as if the pollen was in a saltshaker with small holes through which it has to exit… except that if nothing shakes it, the pollen simply stays put.
Sometimes a gust of wind is enough to pollinate a tomato flower, but fruit set is much better when it’s visited by an insect that specializes in “buzz pollination” (also called sonication). Usually it’s a bumblebee (difference between a honeybee and bumblebee). It clings onto the flower, often hanging upside down, and starts to vibrate its flight muscles. This is the vibration that releases the pollen, ensuring fertilization. In fact, bumblebees do such a great job at buzz pollination that commercial tomato growers release them into their greenhouses to ensure an optimal harvest.
Some solitary bees are also good buzz pollinators. But not honey bees.
There may be several reasons why bumblebees and solitary bees are not visiting your tomato flowers. Maybe there is simply aren’t any in your vicinity (sometimes the case in cities or on balconies or rooftops) or you’ve killed them off with an insecticide spray (you can’t readily use pesticides when you need to attract bumblebees!). Sometimes predators simply get them all (some cats, for example, eat bumblebees as if they were candy!).
However, the fault can also be with the bumblebees themselves. They are very reluctant to venture out on rainy days or when it’s very hot. In situations like these, toothbrush pollination can be very helpful.
To Buzz Pollinate Effectively
Visit your tomato flowers between 10 am and 4 pm, when the pistil is most receptive. And again, you do not need to touch the face of the flower. Just place the brush to the back of the flower the flower and turn it on a few seconds.
If you don’t have an electric toothbrush, a personal vibrator will also work… but what will your neighbors think?
Of course, you can also purchase a specific pollination device for tomatoes from a greenhouse supplier… but an inexpensive electric toothbrush, available for a few bucks in any drug store, is just as efficient and much, much cheaper.
I don’t want to leave you with the impression that an electric toothbrush is always the solution to poor fruit set in tomatoes. Sometimes there are other factors involved over which you have no control.
For example, when temperatures remain above 85˚ (30˚C) during the day and 75˚F (24˚C) at night, tomato pollen is often simply not viable. There is no use buzzing the flowers; all you can do is to wait for the return of cooler temperatures that will allow fruit set to begin again. If you live in an area where summers are always torrid, you might like to look into growing tomatoes known for extra heat tolerance, like ‘Florida 91’, ‘Heatmaster’, ‘Summer Set’ and ‘Solar Flare’.
If ever the air is extremely dry, the pollen will dry out as it forms and won’t stick to the pistil, a problem in regions with an arid climate.
When the air is very humid, pollen may be viable, but tends to stick together and thus won’t readily fall onto the stigma. Here buzzing the flower with an electric toothbrush may be of some help, but probably won’t give perfect pollination.
Other Plants That Require Buzz Pollination
The same problem occurs with other plants in the Solanaceae (tomato family) – eggplants, peppers, etc. – because they share the same stamen tube and hidden pistil and require the same buzz pollination. I find that eggplants, especially, often seem to need help. Thus a quick tour of your veggie bed with a toothbrush can be very helpful.
Sure, your neighbors will think you are nuts at first, but when they see your results, they’ll soon be asking to borrow your toothbrush!