Tomato Blossom Drop: Causes and How to Fix It

Tomato plants with tons of yellow flowers are a super exciting sight, proving you’re on your way to a delicious harvest. That’s why it’s particularly disappointing when those blossoms fall to the ground without setting fruit.

This problem, known as blossom drop, affects tomato plants everywhere, significantly reducing yields. While some flower loss is normal during the growing season, excessive blossom drop indicates underlying problems that require attention.

Understanding the possible factors that cause blossom drop allows you to implement targeted solutions rather than guessing at remedies. Check which one of these causes below is most likely and apply the relevant fix to avoid the same problems in the future.

Temperature Fluctuations

Temperature extremes are the most common cause of tomato blossom drop. Tomatoes develop and retain flowers most effectively when daytime temperatures range between 70-85°F (21-29°C) and nighttime temperatures stay above 55°F (13°C). Outside these ranges, pollen viability declines dramatically.

High temperatures create particularly challenging conditions for tomato reproduction. When daytime temperatures exceed 90°F (32°C), pollen becomes sticky and fails to release properly from the anthers. That, combined with possible water stress, is a recipe for disaster.

Cold temperatures similarly disrupt the reproductive process. Nighttime temperatures below 55°F (13°C) impair pollen development. While the blossoms themselves may appear normal, the elements inside don’t work as they should. The flowers will drop before they ever turn into fruits.

How to Fix It

Several practical approaches help minimize temperature-related blossom drop. For early-season cool temperatures, protective measures like row covers help maintain warmer air around plants. Don’t worry if you lose a few early flowers to the cold, as later blooms should hold once the weather warms up.

For hot weather protection, shade cloth providing 30-40% shade during the hottest part of the day allows flower retention without significantly reducing photosynthesis. Build a temporary structure that you can move around as needed.

Also, time plantings to avoid peak temperature extremes. In regions with hot summers, planting early-maturing varieties in early spring allows fruit to set before extreme heat arrives. Alternatively, planting heat-tolerant varieties for summer production allows for extended production while minimizing blossom drop concerns.

Humidity Extremes

Humidity levels also impact tomato pollination and fruit set, with both high and low extremes contributing to blossom drop.

Excessively high humidity (above 80%) prevents proper pollen release from the anthers, as the sticky pollen clumps together rather than dispersing freely. Additionally, high humidity combined with warm temperatures creates ideal conditions for fungal diseases that can attack flower structures. The resulting blossom drop often gets mistakenly attributed only to heat when humidity is the primary culprit.

Conversely, very low humidity (below 30%) reduces the pollination window dramatically. In arid regions or during drought conditions, flowers may appear normal but fail to set fruit because they dry out before fertilization can occur.

How to Fix It

In high-humidity environments, improve air circulation. Proper plant spacing and pruning of excess foliage all help reduce humidity around flowers.

For low-humidity conditions, maintaining consistent soil moisture helps plants transpire adequately, creating a slightly higher humidity zone around the foliage and flowers. Mulching soil surfaces reduces evaporation, too.

If you’re struggling to adjust conditions outdoors, you can also try hand pollinating your tomatoes at the right time to reduce blossom drop.

Lack of Pollination

Tomatoes require proper pollination for fruit development. Flowers that are not pollinated will eventually drop off the plant.

While tomatoes are self-pollinating (containing both male and female parts within each flower), they still need movement to distribute pollen from the anthers to the stigma. In outdoor settings, this typically occurs through wind vibration or insect activity.

Several factors can interfere with natural pollination processes. Excessive rainfall or extended cloudy periods reduce bee activity. Urban environments with limited pollinator populations or enclosed spaces like greenhouses and covered patios also have issues with blossom drop.

The symptoms of pollination-related blossom drop differ slightly from other causes. Flowers often remain attached longer before dropping, and plants may retain a few fruits while dropping many flowers. This is because random flowers receive sufficient pollination through occasional insect visits or wind gusts, while the majority remain unfertilized.

How to Fix It

Manually pollinating tomato flowers is an effective solution for this cause of blossom drop. Gently shaking plants during the dry part of the day, using a small electric toothbrush pressed against flower clusters to vibrate pollen loose, or brushing the pollen on all, improves pollination rates.

Creating pollinator-friendly garden environments helps address this issue for outdoor tomatoes. Plant flowering herbs and annuals near tomato patches to attract bees and other beneficial insects that assist with pollination. Also, reduce pesticide use, especially during morning hours when pollinators are most active, to encourage these helpful visitors.

Inconsistent Watering

Irregular watering disrupts tomato plants’ processes, triggering blossom drop as the plant redirects resources toward survival rather than reproduction.

Tomatoes require consistent soil moisture (not too wet and never completely dry) to maintain the steady nutrient flow that supports flower development and fruit set.

The stress response to water fluctuations often causes blossom drop before any visible wilting occurs. When soil moisture drops suddenly, plants drop flowers to conserve resources. Annoyingly, a heavy watering following drought creates another form of stress that can cause a second round of blossom drop as the plant adjusts to rapidly changing water availability.

In this case of tomato blossom drop, flowers fall while still small and undeveloped, yellow leaves appear near the base of the plant, and drop coincides with soil moisture extremes.

How to Fix It

Consistent watering prevents this cause of blossom drop. Deep, thorough watering when the top two inches of soil feels dry maintains adequate moisture without creating waterlogged conditions. Frequency depends on climate, soil type, and plant size, but typically ranges from every 2-3 days in hot weather to weekly in moderate conditions.

Mulching significantly improves consistency by reducing evaporation and moderating soil temperature fluctuations. Apply 2-3 inches of organic mulch around the plants, keeping it several inches away from the main stem.

Nutrient Imbalance

While several nutrient deficiencies can contribute to tomato blossom drop, excessive nitrogen most commonly causes this problem in home gardens. High nitrogen levels stimulate lush foliage growth at the expense of flowering and fruiting, creating impressive-looking plants that produce few tomatoes.

Phosphorus also plays a critical role in flower development and fruit set. Deficiencies in this nutrient commonly cause stunted growth along with poor flowering and blossom drop.

Cold soils exacerbate phosphorus deficiency by reducing the nutrient’s availability to plants, explaining why early-season tomatoes sometimes drop flowers despite adequate soil phosphorus levels.

How to Fix It

Start with a soil test to identify the issue. Test results reveal specific deficiencies and imbalances, allowing targeted amendments rather than generalized applications. You don’t want to make an imbalance worse by applying the wrong fix.

Choose a liquid fertilizer with nutrients more readily available. Also keep in mind that this is a temporary fix, and long-term adjustments will need to be made to your soil to resolve consistent imbalances.

Pest Damage

Although not as common, pests can indirectly contribute to tomato blossom drop by damaging plant structures or creating stress that triggers tomato blossom drop.

Thrips cause particularly severe blossom drop by feeding directly on flower parts. These tiny insects suck plant fluids, damaging the delicate reproductive structures within flowers. Affected blossoms typically show small black fecal spots and silvery scarring before dropping.

Spider mites similarly contribute to blossom drop, particularly during hot, dry conditions. These nearly microscopic pests drain plant vitality by feeding on leaf undersides, reducing the energy available for flower and fruit development. The overall stress response often leads to blossom drop even if the mites don’t directly attack the blossoms themselves.

Larger pests like stink bugs and leaf-footed bugs pierce flower stems and developing fruits, introducing toxins and pathogens. These insects often feed unnoticed on developing flower clusters, with the damage becoming apparent only when blossoms drop without setting fruit.

How to Fix It

Pest management is always important when it comes to tomatoes, as there are so many bugs that find these plants as delicious as we do. Implementing integrated pest management practices helps prevent pest-related blossom drop before it becomes an issue.

Regular inspection of plants, especially flower clusters and leaf undersides, allows early detection before populations reach damaging levels. Encourage beneficial insects like ladybugs and lacewings to help control thrips and mites naturally.

For established pest problems, insecticidal soaps or neem oil protect against various pests while remaining relatively gentle on beneficial insects when used properly and applied at the correct time. For severe infestations, targeted insecticides may be necessary, but always apply these in the evening when pollinators are less active.

Maintaining proper nutrition, watering consistently, and providing adequate spacing for air circulation reduces plant stress, making tomatoes less likely to drop flowers when minor pest issues do occur.