3 Tomato Plant Problems and How to Prevent Them

Tomatoes are one of the most popular vegetables to grow in home gardens. However, tomato plants are susceptible to various diseases, pests and environmental stresses that can severely impact growth, yield and fruit quality. Being able to identify and prevent common tomato plant problems is key to success when growing tomatoes. This comprehensive guide covers the three most common tomato plant problems and provides useful tips to prevent them.

Poor Fruit Set

Poor fruit set, where the number of tomatoes produced is low relative to the number of flowers on the plant, is one of the most common tomato growing problems. There are several potential causes of poor fruit set in tomatoes:

Improper Pollination

Tomatoes require pollination to produce fruit. Insufficient pollination leads to flower drop and poor fruit set. Causes of poor pollination include:

  • Cold temperatures – Pollen viability declines below 50°F. Optimal pollination occurs between 60-85°F.
  • Hot temperatures – Extreme heat over 90°F can damage pollen.
  • Low humidity – Pollen grains lose viability when the air is too dry.
  • Inadequate sunlight – Lack of sun exposure inhibits pollen production.
  • Small pollinator population – With only self-pollinating flowers, tomato plants rely on wind or buzz pollination from bees. Insufficient pollinator visits limits pollination.

Prevention Tips for Improper Pollination:

  • Maintain temperatures between 60-90°F during flowering and fruit set. Provide shade during periods of extreme heat.
  • Avoid planting during midsummer when night temperatures may exceed 75°F which can impact pollen viability.
  • Consider using a humidifier or misting system to increase humidity around plants during flowering.
  • Ensure tomato plants receive at least 6-8 hours of direct sun daily.
  • Attract pollinators by planting bee-friendly flowers near or around the garden. Buy commercially available pollinators like bumble bees. Gently shake tomato plants daily to promote self-pollination.

Nutrient Deficiencies

Lacking proper nutrition inhibits a plant’s ability to support fruit development. Deficiencies in nitrogen, phosphorus, or potassium frequently contribute to poor fruit set.

Prevention Tips for Nutrient Deficiencies:

  • Before planting, test soil and amend accordingly with organic matter and fertilizers based on recommendations.
  • Side-dress plants with nitrogen fertilizer when the first flowers appear and again halfway through fruit development. Use a nitrogen-phosphorus-potassium balanced fertilizer.
  • For container-grown plants, apply a water-soluble tomato fertilizer every 2-3 weeks according to label directions.
  • Mulch around plants to conserve soil moisture and nutrients. Utilize compost and organic matter when mulching.
  • Check pH levels regularly and lime soil to maintain optimal range of 6.0-7.0.

Environmental Stress

Exposure to drought, extreme temperatures, flooding, or herbicide damage during flowering and fruit set causes stress. The plant subsequently drops flowers and small fruits.

Prevention Tips for Environmental Stress:

  • Maintain consistent soil moisture by mulching and watering when top inch becomes dry. Avoid overwatering.
  • Monitor forecasts and protect plants from extreme cold and hot temperatures using covers, tunnels, etc.
  • Support plants with stakes and prune suckers to improve air circulation. Proper spacing between plants also limits humidity issues.
  • Ensure tomato plants are exposed to minimal herbicide drift from nearby applications.

Blossom End Rot

Blossom end rot is a common tomato disorder where leathery, black patches form on the bottom of fruits. It is caused by a lack of calcium in developing tomatoes. Insufficient watering is the most common cause as uneven soil moisture inhibits calcium absorption and distribution.

Prevention Tips for Blossom End Rot:

  • Maintain even soil moisture by mulching and consistent watering. Drip irrigation can help stabilize moisture levels.
  • Test soil pH and add lime if needed to reach an optimal range between 6.0-7.0 which supports calcium availability.
  • Amend soil with compost or organic matter which improves moisture retention.
  • Use a calcium supplement or fertilizer with calcium during fruit development. Spray liquid calcium directly onto fruits and flowers.
  • Select tomato varieties labeled as resistant to blossom end rot. Some options include Defiant, Iron Lady, and Sun Leaper.
  • Limit excessive nitrogen fertilization which can promote rapid plant growth and moisture deficiencies.

Late Blight

Late blight is a devastating tomato disease caused by the Phytophthora infestans fungus-like organism. Symptoms include large, dark brown spots on leaves and stems that quickly spread. Fruit become brown and mushy with white fungal growth by the stem end. Diseased plants die rapidly.

Prevention Tips for Late Blight:

  • Select tomato varieties labeled as late blight resistant. Some resistant options include Legend, Mountain Magic, and Jasper F1.
  • Avoid overhead watering which spreads spores. Use drip irrigation or soaker hoses.
  • Stake or trellis plants to improve air circulation and reduce periods of leaf wetness. Prune plants to prevent overcrowding.
  • Remove and destroy all tomato debris after harvest. The fungus overwinters in soil so can re-emerge the next season.
  • Apply fungicides preventatively during damp conditions conducive to disease development. Chlorothalonil and maneb are effective options. Always follow label instructions.
  • At the end of the season, treat soil with lime to increase pH above 6.0 which reduces fungal survival. Solarize soil with black plastic to trap heat and kill fungal spores.

Frequently Asked Questions About Tomato Plant Problems

What causes my tomato plants to have flowers but no fruit?

The most common causes of tomato flowers not producing fruit are inadequate pollination, extreme heat or cold during flowering, and insufficient light exposure. Ensure proper pollination, maintain temperatures between 60-90°F, and provide at least 6-8 hours of sunlight.

How can I stop blossom end rot on tomatoes?

Blossom end rot is caused by a calcium deficiency brought on by uneven soil moisture. To prevent it, maintain consistent watering, amend soil with organic matter, use calcium supplements, choose resistant varieties, and avoid over-fertilization.

What is causing the spots on my tomato plant leaves?

Leaf spots can be caused by fungal diseases like early blight, late blight, leaf mold, or bacterial spot. Improve airflow and reduce humidity around plants. Remove and destroy affected foliage. Apply fungicides labeled for tomato diseases.

Why are the bottom leaves yellowing on my tomato plants?

Yellowing of older leaves often indicates nitrogen deficiency. Apply a nitrogen fertilizer or side-dress plants with compost. Ensure plants receive 1-2 inches of water weekly. Test soil pH and correct if needed.

How do you treat blossom end rot?

There is no treatment to reverse blossom end rot once symptoms develop. Prevent it by maintaining even soil moisture, applying calcium supplements, and mulching plants. Remove damaged fruit to prevent further spread.

What causes my tomato plant leaves to curl?

Curled tomato leaves are often caused by herbicide injury, viral diseases like tomato mosaic, or environmental stresses like drought. Rule out chemical damage. Control viruses by planting resistant varieties. Improve growing conditions to reduce stress.

How can I stop tomato diseases organically?

Prevent tomato diseases naturally by improving airflow, crop rotation, selecting resistant varieties, proper watering, and applying organic fungicides like neem oil or copper sulfate. Maintain garden cleanliness and quickly remove diseased plants.

What are signs my tomato plant is dying?

Signs a tomato plant is dying include stunted growth, yellowing or browning leaves, leaf drop, wilting, lesions on leaves or fruits, fungi on leaves or stems, rotting fruit, and plant collapse. Identify the specific problem and remedy it if possible.

Should tomato plants be staked?

Staking or trellising tomato plants improves air circulation which reduces disease risk. It also prevents fruit from contacting soil and keeps plants from sprawling. Determinate varieties only need caging while indeterminate benefit from stakes or trellises.

How close should tomato plants be spaced?

Space indeterminate tomatoes 18-24 inches apart in rows spaced 3 feet apart. Allow 2-3 feet between determinate tomato plants in rows 3 feet apart. Closer spacing creates humidity and air circulation issues conducive to disease development.


Growing healthy, productive tomato plants requires preventing and managing common issues like blossom end rot, poor fruit set, and fungal disease. Provide proper nutrition and moisture. Optimize light exposure and temperature ranges. Improve air flow. Employ preventative disease management techniques. Select resistant varieties. With careful attention, your homegrown tomatoes will thrive! Proper site preparation, variety selection, and proactive care offers the best defense against tomato plant problems.

Summary of Key Points

  • Poor fruit set is often caused by insufficient pollination, nutrient deficiencies, or environmental stresses during flowering/fruiting. Maintain proper pollination conditions, fertilize appropriately, and minimize plant stress.
  • Prevent blossom end rot by consistent watering, adding calcium supplements, liming acidic soil, and providing proper nutrition. Avoid excessive nitrogen.
  • Control late blight by selecting resistant varieties, drip irrigating, improving airflow, applying fungicides, removing debris, and solarizing soil.
  • Rule out pollination issues, heat/cold damage, and insufficient sunlight when flowers fail to produce fruits.
  • Even moisture, calcium supplementation, and organic matter amendments prevent blossom end rot in tomatoes.
  • Leaf spots are usually caused by fungal or bacterial diseases favored by humidity and poor air circulation. Improve growing conditions and use preventative fungicide applications.
  • Properly stake, trellis and space plants. Water uniformly, fertilize appropriately, and control diseases to keep tomato plants healthy.