Why are My Tomato Flowers Falling Off and Not Making Fruit?

Understanding the Problem

Overview of Tomato Flower Drop

Tomato blossom drop, or tomato flowers falling off, is a common issue many gardeners face. This phenomenon occurs when tomato flowers fail to set fruit and fall prematurely from the plant, which can significantly impact the yield in a vegetable garden.

Tomato plants may experience flower drop due to several factors, including extreme temperatures, inconsistent soil moisture, and improper nutrition. Both high daytime temperatures and low nighttime temperatures can cause blossom drop, as the ideal range for tomato blossom set is between 70°F to 85°F during the day and above 55°F at night.

Additionally, humidity levels outside the ideal humidity range and irregular watering can lead to plant stress and further exacerbate the problem. To prevent blossom drop, ensure consistent watering, proper disease control, and possibly the use of heat tolerant varieties and techniques to encourage beneficial insects like bumble bees for better pollination.

Importance of Addressing the Issue

Addressing the issue of tomato flowers falling off is vital for a productive vegetable garden. Blossom drop in tomato plants can be caused by extreme temperatures, improper soil moisture, and nutrient imbalances.

Ensuring healthy plants involves maintaining the ideal daytime temperatures range and avoiding high daytime temperatures and low nighttime temperatures. To prevent blossom drop, practice consistent watering and conduct a soil test to ensure proper nutrition.

Selecting heat tolerant varieties can help mitigate the effects of high daytime temperatures and low nighttime temperatures. Encouraging beneficial insects like bumble bees improves pollination, reducing the chances of flower drop.

Finally, managing plant stress through appropriate disease control and avoiding too much nitrogen helps tomatoes grow and set fruit successfully.

Blossom Drop and Your Tomatoes

Now that your tomatoes are bursting with growth and flowers and you are anticipating the red fruit that will develop, you find flowers dropping or withering on the plant. Why is that happening? The problem is called blossom drop. The main reason is that the flowers are not getting pollinated. Tomatoes have perfect flowers, meaning both male and female reproductive organs are in the same flower. The pollen is moved from the male part (stamen) to the female part (pistil) by wind movement of the plant or by vibration of the flower by bumble bees or other pollinators. So what are the causes of lack of pollination? 

Abiotic Stresses That Lead to Blossom Drop

• Temperature – high or low temperatures can negatively effect pollination. The ideal temps for good pollination and producing fruit is between 70-85°F. If the daytime temperature rises above 85°F, or nighttime temps rise above 70°F or drop below 55°F, the pollen becomes nonviable, therefore no pollination occurs and the yellow flower dries up and falls off.
• Relative Humidity – The ideal range is between 40-70%.
• Lack of Water or Too Much Water
• Not Enough Light
• Excessive Wind – dries up the flower or physically damages the yellow flowers
• Improper Nutrition – Over fertilizing with nitrogen can also cause your plants to have lush growth at the expense of setting fruit. Under fertilizing will lead to plants that cannot supply enough energy to grow fruit. There is a fine line between over fertilizing and under fertilizing.

Biotic Stresses That Lead to Blossom Drop

• Insects
• Disease
• Heavy Fruit Set – not enough energy can be supplied to the growing flowers and producing fruit. Usually happens in the initial fruit that is set on the plants.

What Can You do to Prevent Blossom Drop?

• Best to keep your plants evenly and well-watered. Mulch around your plants to help conserve water and keep moisture levels even. This will also help prevent cracking and as long as calcium is sufficient in your soil, will reduce the incidence of blossom end rot.
• Put up some shade cloth (30% is a good option) over the plants to help cool them off a bit. This can be removed when temps drop back down to below 85-90°F.
• Best to follow the feeding label on the fertilizer and do not use ones that have high amounts of nitrogen on the label. A good balanced all-purpose fertilizer is a good choice for feeding your tomato variety in the garden bed.
• Practice crop rotation and do not put Nightshade plants (tomatoes, peppers, potatoes...) in the same bed year after year.

See our full collection of tomato seeds for sale, and visit our Tomato Resource Center for the latest blogs, videos and gardening tips to grow tomatoes in any growing season.

FAQs About Why are My Tomato Flowers Falling Off and Not Making Fruit?

What causes tomato blossom drop?

Tomato blossom drop occurs due to various factors such as temperature fluctuations, including high daytime temperatures and low nighttime temperatures, which can disrupt fruit set. Other factors like humidity levels falling, hot weather, high nighttime temperatures, and water stress also contribute to blossom drop.

How do high temperatures affect tomato plants and fruit production?

High temperatures, especially during the growing season, can cause stress to tomato plants, leading to blossom drop and poor fruit set. It's essential to provide adequate shade or choose heat-tolerant varieties to mitigate these effects.

What role do night temperatures play in tomato blossom drop?

Low nighttime temperatures can also cause tomato flowers to drop prematurely, hindering fruit formation. Monitoring and protecting plants during cooler nights can help prevent this issue.

How does water stress impact tomato plants and their flowers?

Water stress, whether from irregular watering or dry weather conditions, can result in tomato flowers falling off before they can set fruit. Consistent and deep watering practices are crucial to maintaining plant health and encouraging fruit development.

What are some tips to prevent tomato blossom drop?

To prevent tomato blossom drop, ensure plants are healthy with lush green leaves, provide adequate humidity levels, avoid extreme temperatures (both high and low), and encourage pollination by planting in full sun and attracting beneficial insects like bees.

How can I improve pollination to ensure fruit production?

Enhance pollination by maintaining high humidity levels, planting in full sun, and even using techniques like gently shaking plants or using an electric toothbrush near blossoms to simulate bee activity and improve fruit set.