Tomatoes, Solanum lycopersicum, are annual fruits that grow in Zones 2 to 11 in full sun with organically-rich, moist, slightly acidic, well-draining soil.
Flowering is usually followed by fruiting after 65 to 100 days, depending on the cultivar.
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Sometimes, gardeners are delighted to see an abundance of flowers only to be disappointed by few to no tomatoes.
Our guide to growing tomatoes has all you need to know to cultivate robust plants in your vegetable garden.
This article discusses why the reproductive cycle is sometimes disrupted resulting in flower production with few to no fruits.
Here’s our lineup:
7 Reasons for Flowers But No Fruits
One or more of the following seven entries may contribute to tomatoes failing to form fruit in spite of flowering.
Let’s consider them.
1. Lack of Light
Tomatoes need full sun to thrive, so choose a location with six or more hours of direct sunlight daily.
Sowing in the shade results in weak plants with sparse foliage and will contribute to few flowers and fruits.
In addition, excess foliage can create unwanted shade that inhibits flower formation and pollination.
The lack of airflow around the foliage increases the humidity, creating prime breeding ground for diseases that may also adversely affect the reproductive cycle.
When starting a new garden, place the tomatoes in the sunniest part.
If you have planted them in the wrong spot, you may be able to successfully move young specimens before they start blooming to a brighter spot.
2. Moisture Stress
During the growing season, supply one to two inches of water weekly to support healthy flowers, foliage, fruits, and roots.
Too much water causes oversaturation and poor nutrient uptake, while too little moisture dries out roots, impairing their function.
Also, under- and overwatering increases vulnerability to pests and diseases that may undermine the flower-to-fruit transition.
Sow in well-draining soil and use a moisture meter to avoid adding unnecessary supplemental water.
Water regularly to prevent the soil from drying out. Listen to the weather forecast and water deeply before a heatwave. Increase moisture during periods of drought and high winds.
Consider installing an irrigation system or using a soaker hose to eliminate the need to stand for prolonged periods with a garden hose.
3. Nutrient Imbalance
Nutrient deficiencies and excesses impair health and performance. A phosphorous deficiency can cause yellowing, poor flowering, and fruiting.
Excess nitrogen results in too many leaves, reducing flowering, blocking sunlight, increasing ambient moisture, restricting wind movement, and ultimately inhibiting pollination.
So the flowers appear, but without successful pollination, there won’t be any fruit.
As heavy feeders, tomatoes benefit from a generous supply of nutrients, whether that’s through supplemental fertilizer or planting in organically-rich soil.
Conduct a soil test through your local extension office to learn your soil’s composition and amend it as recommended.
You can apply fertilizer to support robust flowering and strong yields.
Choose a granular, slow-release product with a lower nitrogen content and higher phosphorus and potassium levels to inhibit excess leaf production while supporting roots and flowering.
Burpee’s Organic Tomato + Vegetable Granular Food releases an initial burst of nutrients and then feeds slowly for up to three months.
It has an NPK ratio of 3-6-4 for lower nitrogen with higher phosphorus and potassium to support root development, flowering, and fruiting.
Burpee Organic Tomato Vegetable Plant Food
Burpee Organic Tomato + Vegetable Granular Food 3-6-4 is available from Burpee.
4. Pests and Disease
Well-nourished plants in ideal growing environments are the least likely to suffer from problems with pests and pathogens.
However, even with best practices, plants can sometimes be infested or infected.
Pests inflict damage by feeding, reproducing, and sheltering on plant tissue and some may also be disease vectors.
Pests like aphids, flea beetles, leafhoppers, spider mites, and whiteflies are sapsuckers that cause stunted growth as well as damage to foliage, flowers, and fruit.
Tomato hornworms are moth larvae that defoliate plants, consuming entire leaves, flowers, and fruits.
Most of these can be treated with neem oil. You can also handpick and destroy hornworms.
In addition to pests, two diseases likely to disrupt reproduction are:
Big bud disease and tomato yellow leaf curl virus. Big bud disease is vectored by the beet leafhopper, Neoaliturus tenellus, and causes oversized buds to develop, followed by few to no fruits.
Symptoms include green petal-like sepals that fail to open but may sprout green shoots.
Nearby leaves are tiny, curled, yellow or purplish, growth may be dense and bushy, and the fruit may grow but will likely be hard and deformed.
Remove and destroy affected specimens and treat healthy foliage preventatively with neem oil to deter leafhoppers.
The silverleaf whitefly, Bemisia tabaci, spreads tomato yellow leaf curl virus. It causes yellow, curing leaves, stunted growth, and dropping flowers. When infected in the early growth stages, plants may fail to fruit.
Treatment includes removing and destroying affected specimens and treating healthy ones with neem oil to prevent whitefly infestation.
Preventative measures to avoid pests and disease include meeting all cultural requirements for soil, sun, and water, learning to recognize symptoms, and monitoring plants regularly.
5. Pollination Failure
Pollination failure is a primary cause of poor fruit production.
Tomatoes are pollinated by wind and by bees, a process known as “buzz pollination.”
If you grow in a greenhouse or sheltered area or have an unusually atmospherically calm growing season, a lack of wind may contribute to lack of pollination and fruit set.
Gardeners can stimulate pollination manually by flicking the flower stems gently with the thumb and index finger to release pollen, then using a clean, natural bristle fine artist’s paintbrush or cotton swab to gently swipe inside the flower to distribute it.
Our guide to pollinating tomatoes by hand has details.
6. Unpruned Vines
Pruning tomatoes is not mandatory. However, if you grow indeterminate types, some careful pruning can produce higher yields and larger fruits.
Indeterminate cultivars left to their own designs become leggy with many leaves and stems.
The excessive foliage inhibits flower formation, obscures flowers, and restricts the air movement essential for pollination.
It may also impede moisture evaporation, causing the pollen to clump and fertilization to fail.
To support maximum yields, use sanitized shears to remove suckers to improve airflow.
These stems sprout in the crook between vertical main stems and lateral branches and at the base of the main stems. Cut them as close to their point of origin as possible.
Our guide to pruning tomato plants has more information.
7. Weather Extremes
Temperature fluctuations, unseasonably cold or hot conditions, drought, excessive rainfall, frost, hail, and high winds are all examples of extreme weather that may negatively impact plants during the growing season.
Stress may delay flowering or hasten it for the species to survive. They may also slow the overall rate of growth and drop leaves to conserve resources.
Sometimes, despite best efforts to withstand adversity, strong winds crisp the leaves and blow the blossoms away, and with them, the potential to fruit.
To avoid unhealthy stressors, listen to weather forecasts so you can act preemptively to protect your plants.
- When cold temperatures with or without frost are imminent:
- Water deeply over the root zone, not the leaves.
- To insulate the roots, apply two to three inches of bark or straw mulch around, but not touching the main stems.
- Place a clear, bell-shaped glass cloche over young specimens.
- Wrap larger, more mature specimens in soft fleece or burlap and tie it loosely with twine.
Remove the protective coverings when the weather returns to normal.
In advance of a heatwave:
- Water well before the temperature soars; early in the day is best.
- Monitor for signs of stress, like wilting, yellow, brown, and/or crisp foliage, and leaf drop.
Choose a planting location away from prevailing winds.
Shield plants from gusty conditions with netting secured with garden stakes to keep flowers and fruits from detaching.
Optimal Flowering and Fruiting
We’ve discussed seven reasons why tomato plants may produce blooms but few fruits and suggested ways you can prevent this from happening.
Have you had tomatoes fail to set fruit? Please tell us about your experience in the comments section below.
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