Top 3 Reasons Why Your Tomatoes Are Not Setting Fruit

, written by Benedict Vanheems gb flag

Tomato flowers not setting fruit

Are you picking plenty of tomatoes this season? If not, take heart in the fact you’re certainly not the only one. A lack of fruit set – when flowers fail to produce fruits before they wither and drop – is one of the most common complaints among tomato growers. It’s frustrating and it’s not fair, particularly given all the attention you’ve no doubt lavished on your plants to get them this far.

Whether you’re yet to pick a solitary tomato, or your plants have abruptly stopped producing, the reasons behind the lack of fruit are often predictable and easy enough to fix. So don’t despair – read on and see if your plants can be persuaded to behave.

Tomato flowers with tomato fruit setting

1. Insufficient Pollination

The first thing to consider is how easy it might be for pollinating insects to reach your crops. Tomatoes are self-fertile, which means each flower can pollinate itself. Nevertheless, the presence of bees and/or wind dramatically improves pollination by nudging the flowers just enough to help dislodge the pollen from the stamens.

Bumblebees are especially good at this. As they contract their flight muscles (a process called ‘buzz pollination’) these low vibrations literally shake the pollen free, allowing it to drop down onto the stigma – the female part of the flower that catches the pollen.

If you’re growing tomatoes in a greenhouse or polythene tunnel it may be worth considering whether pollinating insects have ready access to the plants. Open up doors and vents, which will also help to create a good through-flow of air, keeping plants cooler and reducing the risk of disease.

You can artificially pollinate tomatoes by lightly shaking the plants yourself to mimic the bee’s buzz. Twang string-lines or canes supporting vining tomatoes, or lift and drop (gently, from a very short distance!) container tomatoes.

Tomato flowers

2. High Heat Levels

In hotter climates, high temperatures can sometimes play havoc with pollination. Hot spells, when daytime temperatures remain above 30ºC (86ºF) and, crucially, nighttime temperatures fail to dip below 24ºC (75ºF), have the undesirable effect of turning pollen sterile. Turns out tomatoes like it hot – but not too hot!

The only thing you can do during a heat wave is bide your time. In the meantime keep plants well watered and healthy, so that when temperatures finally subside they’ll be in an excellent position to ramp up production once more.

Don’t forget that different tomato varieties are suited to different climates. If you’re in a hot part of the world, grow a heat-tolerant variety that is recommended for your region.

An added complication is humidity, or lack of it. Very high humidity can clog the pollen, so it’s unable to drop, while in very dry climates flowers may become so parched that pollen fails to stick and simply rolls straight off. In this instance regular watering may help to raise the humidity around the plants just enough to improve conditions.

Tomato fruits set and ripening

3. Not Enough Fertiliser (or the Wrong Type)

The final factor to consider is soil fertility. Are your tomato plants getting the nutrition they need to grow plump, tasty fruits? Even if you have rich soil, from the moment the first flowers appear you should be feeding your tomatoes with an organic fertiliser that’s high in potassium, or potash. Potash helps promote flower initiation, and hence fruit production.

Keep tomatoes fed with an off-the-shelf tomato fertiliser or make your own high-potash liquid fertiliser for free. Every garden should have a clump of comfrey for home-brewed fertiliser.

Once you’ve done all you can to improve conditions, you’ll just have to be patient and wait for Mother Nature to do the rest. Don’t lose heart because the situation is bound to improve. When it does, the tomatoes will come thick and fast, and then you’ll be wondering what to do with them all!

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Show Comments


"Insufficient Pollination Using an electric tooth brush generates very good vibrations for helping pollination of tomato flowers!"
Jacques on Friday 5 August 2016
"That's an inspired idea! Thanks for sharing Jacques."
Ben Vanheems on Friday 5 August 2016
"I knew about the bees buzz pollination, never thought about using an electric toothbrush to mimic this! That's it, going to use hubbies electric toothbrush and have a bumper harvest!! on a more serious level, this method will really help during these weeks of constant bad weather. "
Joyce Langan on Saturday 6 August 2016
"I touch flower to flower ,or cut one flower and touch 6-7 others ,plus I have lavender flover in my garden and bees come easy "
Kathy on Tuesday 9 August 2016
"I hand pollinate beginning with the first bloom of the season. No special tool needed, I have used sticks or fuzzy weed seed heads and rub the center of the flower, then proceed to the next flower. This method works well for me. I have a huge crop this year. Just hand pollinated again this morning "
Barbara Kuehl on Tuesday 9 August 2016
"Thanks Susan for taking time out of Ur busy schedule to post this for me-- I appreciate Ur thoughtful ways. I have used Q tips to pollinate container Jamaican Scotch Bonnet peppers-- will try that tomorrow at the TBC garden. " Every garden should have a clump of comfrey for home-brewed fertilizer" I copied this from the article. SO I am challenging U to bring comfrey plants to the Herb Plot for 2017 :)"
Ida Richards on Wednesday 10 August 2016
"Hi Kathy and Barbara. Thanks very much for your tips. You guys are definitely self pollinating pros!"
Ben Vanheems on Wednesday 10 August 2016
"I haven't seen a bumble bee for ages?"
Sandy Bowles on Saturday 13 August 2016
"Hi Sandy. Bee populations have declined in many regions. The best we can do is to plant lots of flowers to attract them and avoid using pesticides in the garden."
Ben Vanheems on Saturday 13 August 2016
"Hi My mom used a corn broom ,awesome tomatoes every year "
RON on Wednesday 24 August 2016
"Good stuff "
Ian rotherham on Monday 27 February 2017

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