What if your tomato plants have plenty of flowers, no visible health issues, but no fruit?
Tomatoes are self-pollinating, meaning they have both the male and female parts. This means that they may be able to pollinate and set fruit even without bees, but sometimes things go awry in the reproduction department. Some things we can fix, some we can’t. Here are some of most common causes of tomato flowers but no fruit.
#1 – BLOSSOM DROP
Blossom drop happens because it’s too cold or too hot. According to Ohio State University:
Air temperature is an important factor in the production of tomatoes, which are particularly sensitive to low night temperatures and extremely high temperatures. Blossom drop can occur in early spring when daytime temperatures are warm, but night temperatures fall below 55°F.
This phenomenon will occur during the summer as well, when daytime temperatures are above 90°F and night temperatures are above 75°F.
For high temps, a shade cloth may be used to block some of the afternoon sun and beat the worst of the heat. For cold temps, consider red plastic mulch sheeting (this can go over organic mulch and be reused for several years). You might also find a grow tunnel or floating row cover boosts temps enough to promote fruiting.
#2 – HIGH HUMIDITY
Tomatoes reproduce by their pollen falling from the stamen and pollinating the stigma. Generally this pollination happens by wind, movement and vibration of a bees wings.
High humidity can impede this this process by making the pollen too wet to freely transfer to it’s destination. If you live in a climate with high humidity, you can help pollinate your tomato plants by gently tapping on the flowers or flower stems. Another option is to gently brush pollen from one flower to another with a small paintbrush.
#3 – POOR AIR CIRCULATION
As I mentioned above, flowers are self-pollinating and set pollen via movement. If the air flow around the tomato is hindered, the pollen can not fall and pollinate the stigma. To improve air circulation, try some of the following options:
- Remove some of the foliage, such as suckers.
- Don’t plant your tomatoes too close. Space determinate varieties 12-24″ apart and indeterminate varieties 36-48″ apart.
- Trellis your tomato plants. Grow your tomatoes vertically to improve air circulation. (See tomato trellis ideas.)
- Don’t plant next to a building or structure. Instead, plant your tomatoes where they have open air on all sides.
#4 – TOO MANY FLOWERS
Too many flowers on a tomato plant will cause competition for nutrients among the flowers. As a preservation method, the tomato plant will automatically abort and drop flowers. After your plant goes through a fruiting process, this problem should correct itself without intervention as long as the soil is good.
Lots of Blooms but No Tomatoes
If you have lots of flowers and no tomatoes. Temperature and poor pollination are generally to blame here. Temperature – Tomato plants require warm temps to flourish (65-70 F./18-21 C. during day, at least 55 F./13 C. at night to set fruit). However, if the temperature rises too much (above 85 F./29 C.), they will fail to bloom, thus not producing fruit. If you have plenty of big blooms but no tomatoes, it may be too cold and wet or too hot and dry. This results in what is known as blossom drop and will, of course, make it much more difficult for plants to produce fruit. Poor pollination – Weather can also be a factor with pollination. Cold, windy, or wet weather will limit the amount of bee activity, which is helpful for pollination to occur and fruits to set. Without these pollinators, you will have only a few tomatoes. Once weather returns to normal, however, this should right itself or you can hand pollinate them instead.
Read more at Gardening Know How: What Causes Lots Of Flowers And No Tomatoes On Tomato Plants https://www.gardeningknowhow.com/edible/vegetables/tomato/tomato-blossoms-no-tomatoes.htm
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.
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.
3. Not Enough Fertilizer (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 fertilizer 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 fertilizer or make your own high-potash liquid fertilizer for free. Every garden should have a clump of comfrey for home-brewed fertilizer.
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!