You nurture your tomato plants through spring, waiting for those first ripe tomatoes of the season. Your plants grow well and begin flowering, but no fruit appears. What causes tomato plants to flower yet fail to set fruit? Read on to learn the common reasons for lack of tomatoes and what to do to resolve the problem.
Botany of Tomato Flowering and Fruiting
Understanding the tomato plant reproductive process helps identify potential causes of flowering without fruiting:
Tomatoes produce both self-pollinating flowers and flowers requiring pollination.
Lack of pollination results in blossom drop without fruit set.
After pollination, the ovary develops into a tomato over several weeks.
Stress during fruit formation leads to aborted development.
Issues with either pollination or fruit formation can lead to lush leafy plants with flowers but no tomatoes.
Aspects of the plant’s environment commonly inhibit fruit production:
Tomatoes thrive in warm conditions, ideally with daytime temperatures around 70-80°F and nights above 55°F.
Cool temperatures below 55°F hinder pollen viability and fertilization.
Hot weather over 90°F during flowering can cause pollen sterility and flower drop.
Low Light Levels
Tomatoes are sun lovers. Insufficient sunlight results in poor flower and fruit production.
Plants receiving under 8 hours of direct sun often won’t set fruit.
Fruit that forms in shade is lower quality with less flavor.
While tomatoes need nitrogen for vegetative growth, excess nitrogen leads to lush foliage at the expense of flowers and fruit.
Avoid over-fertilizing with high nitrogen fertilizers.
Let plants deplete soil nitrogen reserves before fruiting.
Tomato plants need consistent moisture for good fruiting.
Drought stress during flowering and fruit set causes abortion of fruit.
Heavy watering after dry periods can crack developing tomatoes.
Lack of pollination prevents fertilization and fruit formation.
Rain, wind, or cool temperatures may limit bee activity.
Indoor plants rely solely on hand pollination.
Diseases & Pests
Tomato diseases and pests damage floral and fruit development:
Foliar diseases like early blight interfere with plant vigor needed for fruiting.
Viruses transmitted by insects cause flowers to drop.
Blossom end rot is worsened by calcium deficiency and moisture stress.
Unhealthy tomato roots can’t support fruit development:
Root bound containers prevent nutrient and water uptake.
Root diseases impede water and nutrient delivery.
Extreme heat cooks roots, especially in raised beds and containers.
Some varieties are predisposed to reproductive issues:
Parthenocarpic varieties produce fruits without pollination.
Naturally shy fruiting types set fewer fruit.
Hybrids sometimes lack viability, vigor, or fruit setting ability.
Cultural & Technical Issues
Cultural practices and plant management can interfere with fruit production:
Overpruning : Pruning and trimming removes plant resources needed for fruiting.
Defoliation : Lost leaves from pests, disease, storms, etc. reduces photosynthesis necessary to grow fruit.
Overcropping : Allowing plants to produce too many clusters can take resources away from ripening.
Negative Allelopathy : Biochemicals from plants like fennel, pepper, and sunflower suppress tomato flowering and fruiting when interplanted together.
Poor Pollination Technique : Outdoor tomatoes need bee activity for thorough pollination. Indoor plants require daily hand pollination using electric toothbrushes or other vibration methods to release pollen. Inconsistent or improper technique results in inadequate pollination and aborted fruit.
Solutions to Promote Tomato Fruiting
Address the above cultural, environmental, and health factors to get your tomato plants producing:
- Provide full sun exposure. Supplement with grow lights if needed.
- Maintain temperatures between 65-80°F consistently.
- Eliminate sources of excess nitrogen.
- Water thoroughly and regularly without oversaturating.
- Improve air circulation and leaf pruning for disease prevention.
- Attract pollinators outdoors. Hand pollinate indoors properly.
- Control pests and promptly remove diseased plants.
- Select more adapted vigorous varieties suited to your climate.
- Allow no more than 4-5 clusters to develop per plant.
- Rule out allelopathic companion plants.
- Check roots for issues and repot root bound plants.
Consistency is key – tomato plants need optimal conditions during both flowering and fruiting to yield ripe tomatoes. A little adjustment to your care regimen should have your plants producing bountiful fruits in no time.
When to Worry About Lack of Tomato Fruiting
While tomatoes sometimes take their time ripening the first set, be concerned if:
- It’s been over 6 weeks since the first flowers appeared without fruits.
- Flower clusters are dropping without forming fruits.
- Numerous flowers fall off the plant when touched or shaken.
- Young fruits form but then shrivel up and die after a few weeks.
- Other disease symptoms like yellowing leaves or dark lesions are present.
If your flowering tomato plants show these signs for more than a few weeks, troubleshoot the potential causes and take corrective actions.
Don’t let a tomato plant covered in flowers fool you – those blossoms must successfully transition into ripe fruits. Make sure to provide ideal environmental conditions and plant health for vigorous flowering and fruit production. Identify and resolve any stresses inhibiting fruit set. With good care, your flowering tomato plants will reward you with abundant juicy tomatoes.