Why Are My Tomato Flowers Falling Off? Causes & Fixes

1. Too Hot or Too Cold Outside

Perhaps the most common cause of blossom drop is temperature. Flowers can fall off for a variety of reasons, but high temperatures are often a culprit. While tomato plants thrive in hot weather, temperatures that are too high can cause stress and negatively impact tomato plants’ ability to reproduce.

A useful daytime growing range is about 70–85°F (21–29°C), although tomato varieties and local conditions differ.

When daytime temperatures stay above about 85–90°F (29–32°C), plants may begin to drop blossoms. Night temperatures below roughly 55°F (13°C), or above about 70–75°F (21–24°C), can also interfere with fruit set.

Tomato blossoms are sensitive to temperature and will fall off if the plant can’t sustain them.

A tomato plant can lose flowers even when its leaves look green and healthy. Do not rely on yellowing or wilting leaves alone to identify temperature-related blossom drop.

If high temperatures are to blame for your plant’s issues, there are a few different solutions depending on whether you’re growing plants in pots, in a greenhouse or in a garden bed.

For container plants, keeping the roots cool and moist is the most effective way of countering the effects of high temperatures.

You can accomplish this by using shade cloth or other materials to provide afternoon shade while still letting the plants get morning sun.

For plants in greenhouses, the best solution is to improve airflow and reduce overall heat.

If cold temperatures are the issue, make sure your plants aren’t exposed to chilly conditions before they’re ready to bear fruit.

While extreme heat is usually the biggest culprit, there are a few other potential causes of blossom drop to consider.

2. Dry or Waterlogged Soil

Tomato plants have fairly high water needs, especially when they’re bearing fruit.

If the soil is too dry, plants can go into survival mode, focusing energy on staying alive rather than reproducing.

While it’s important to keep the soil damp, be sure you aren’t over-watering the plants.

Too much water will lead to water-logging, which prevents roots from getting the oxygen they need to function properly.

The goal is to keep the root zone evenly moist without waterlogging it.

Rather than watering plants on a strict weekly basis, check the soil to see whether it needs water. Push your finger into the soil up to the second knuckle. If the soil is still moist at root depth, check it again later before watering.

When you do water, make sure to water thoroughly.

If you’re growing plants in containers, they may need to be watered more frequently than plants in a garden bed. Containers can dry out very quickly in hot, dry weather.

To help reduce the effects of hot summer weather, apply a layer of clean organic mulch around your plants.

This will help the soil retain moisture and keep plant roots from getting too hot.

Don’t forget to examine the plants themselves. Plants growing in crowded beds may also compete with nearby plants for water and root space.

Soil type can affect moisture retention. If your soil dries out too quickly, appropriate organic matter may help over time. For heavy, compacted ground, read our guide to amending clay soil.

3. Humidity Is Too High or Too Low

Humidity levels can play a major role in a plant’s ability to reproduce. Excessively high or low humidity may prevent tomato blossoms from setting fruit by impacting the plant’s pollination cycle.

Humidity impacts the pollination process by affecting the way pollen travels from the anther to the stigma of the tomato flower.

Tomato blossoms are self-pollinating, which means that they don’t need another plant to provide the necessary pollen to begin the reproduction process. However, pollen still needs to travel from the anther to stigma in order to begin the fertilization process.

Tomato pollen often performs best at moderate relative humidity, roughly 40–70%. Very low humidity may dry the pollen, while very high humidity can make it sticky and harder to release.

High humidity levels are typically an issue for plants that are growing in greenhouses.

You can combat high humidity levels by opening doors and windows to increase airflow throughout your greenhouse.

Give greenhouse plants enough space for air to move around the leaves. If the air is already humid, adding more water will not improve pollination. Instead, focus on ventilation and comfortable growing conditions.

4. Poor Pollination

Flowers may begin to fall off if the plant fails to effectively pollinate them.

Outdoors, wind and visiting insects often help vibrate tomato flowers. In sheltered greenhouses, there may be less movement to release the pollen.

You can help increase the chances of successful pollination by gently tapping the stems of the plant or shaking the plant on a mild, dry day.

The idea is to loosen up the pollen inside the flower. The movement of the plant mimics a breeze that would normally help pollinate the plant. Don’t tap the flowers so hard that the flowers or stems fall off.

While this is a helpful technique, it won’t fix issues with the quality of the pollen.

Even tapping will only help so much if the weather has been particularly hot or cold. If weather has made the pollen nonviable, focus on plant care and wait until new flowers open under more suitable conditions.

5. Too Much Nitrogen

Fertilizers can be a great way to support plant growth, but plants don’t always need more food. More food isn’t always better when it comes to fertilizers. Too much nitrogen may encourage leafy growth at the expense of flowering and fruit production.

You may notice that your plant is producing an abundance of leaves while failing to produce flowers or fruit.

Before buying a new fertilizer, be sure to examine what you’re currently using. Some lawn fertilizers are rich in nitrogen, and applying them to plants can lead to issues. If you’ve been using a nitrogen-rich fertilizer or adding nitrogen to your soil recently, consider switching to a fertilizer that’s specifically designed for fruiting plants.

The best course of action is to apply the fertilizer recommended by the package instructions. You may also want to get a soil test performed to determine what nutrients the soil is lacking.

Once you understand what kind of nutrients the plants are lacking, you can apply the right fertilizer without hurting the plants.

Too much nitrogen can be harmful, but it’s just one of several potential culprits. If you’re still struggling to identify the issue, consider looking at other environmental factors.

6. Lack of Sunlight or General Plant Stress

Tomato plants have fairly high light needs, meaning that they require at least six hours of direct sunlight per day to thrive.

If your plant has been sitting in an area that doesn’t get enough sunlight, it may begin to struggle. Plants that receive too little light may become weak and set fewer fruits.

Plants that don’t get enough light may still be able to produce some fruit, but they’ll likely fail to produce the same amount of fruit as a plant that gets enough sunlight.

Low light can become worse when nearby plants compete for space, water and nutrients.

Poor drainage, root rot, insect infestation or a lack of nutrients can also prevent plants from thriving.

When plants experience overall stress, the blossoms may begin to fall off.

First, take a close look at the plants. Determine whether the plants appear to be healthy or whether something seems off. If you notice signs of distress in the plants, you’ll want to address those issues.

For example, if the plants aren’t getting enough sunlight, you may need to move them to a different area. If the plants have healthy foliage but appear to have poor drainage, you’ll want to improve the drainage in the garden.

Correct the specific issues you can identify without making too many changes at once. If you’re planting a new bed of plants, be sure to use the Vegetable Garden Layout Plans and Spacing guide to ensure that the plants are spaced correctly.