Understanding Why Your Tomatoes Too Small (And How to Make the Fruit Bigger)

It is the wish of every gardener to have a bountiful harvest of large and juicy tomato fruits. Unfortunately, something may happen along the way, and you end up getting small tomatoes. Let’s explore why your tomatoes are too small and how you can make the fruit bigger.

The main reason for small tomatoes is a stressed plant. This problem can stem from inadequate watering, extreme temperatures, insufficient sunlight, extreme humidity, root damage, pests, and diseases.

Why Are My Tomatoes Smaller?

Reasons for small tomato fruits can range from environmental to management practices.  Let’s have a deeper look at each of the factors:

1. Inadequate Watering

According to the Mississippi State University Extension, tomato plants are likely to produce small fruits when they receive inadequate amounts of water during the growing period. Water is a key element in the process of photosynthesis. Without it, the plant will not be able to produce enough energy to enlarge the fruits. 

Inadequate water can result from drought or poor watering techniques. Tomato plants require regular watering throughout the growing period. Timing and the quantity of water are key when irrigating your tomato plant. Avoid overwatering as it can also cause root rot and other fungal issues.

2. Insufficient Sunlight

Insufficient sunlight can also cause tomato plants to produce small fruits. Like any other green plant, tomatoes require enough light to produce energy in the process of photosynthesis. Planting tomatoes adjacent to tall buildings or trees can block the light from reaching the plants. 

Tomatoes require at least 6 to 8 hours of direct sunlight per day to grow healthy and produce large fruits. When your plants are in a shaded area, they will not be able to produce enough energy for fruit development. The plant will use the little energy it produces to sustain itself.

3. High Temperatures

Tomatoes enjoy warm weather. However, the temperatures are not supposed to be too high. They grow best when daytime temperatures are 75 to 85 degrees Fahrenheit (18.3 to 29.4 degrees Celsius) and 60 to 75 degrees Fahrenheit (15.6 to 23.8 degrees Celsius) during the night.

According to the Colorado State University Extension, tomato fruits do not increase in size when the temperatures are too high during the day and too cold at night. Other than small fruits, high temperatures can also delay flowering, fruit formation, and ripening.

4. Incorrect Humidity Levels

When the humidity is too high, the air becomes too sticky, making it too difficult for the male part of the flower to release the pollen. On the other hand, low humidity causes the air to become too dry for the pollen grain to stick on the female part of the flower.

Growing tomatoes in a greenhouse without vents can make your plants inaccessible to pollinators like bumblebees, beetles, and small birds. Heavy use of pesticides near the garden can also kill or turn away pollinators. All these can result in no fruits at all.

5. Root Damage

Small tomatoes may result from root damage.  The roots can be damaged when transplanting, weeding, staking, caging, or due to pests and diseases. Damaged roots may not be able to absorb water, nutrients, and other minerals from the soil properly. 

Planting tomatoes in small pots can also lead to root damage. The roots become entangled together and may not have enough room to absorb the necessary nutrients required by the plant. This may affect the normal development of the plant, including fruit development.

6. Excess Nitrogen

Tomato plants are heavy feeders and require top dressing every 2 weeks. However, you are supposed to go slow on nitrogen when the plant is near flowering. Excess nitrogen encourages the growth of foliage at the expense of flowers and fruit development.

Tomato plants require a balanced fertilizer to grow healthy and produce large fruits. Use a fertilizer that is rich in phosphorus, potassium, and magnesium when the plant is near flowering. 

7. Tomato Variety

Small or large tomatoes also depend on the variety that you planted. Some determinate varieties, like cherry, will produce small fruits and ripen within a short period of time. On the other hand, indeterminate varieties will produce large fruits throughout the growing season.

8. Insect Infestation and Diseases

Tomato plants weakened by pests and diseases are likely to produce small fruits. Insect pests, in particular, are known to suck sap from the plant. The juices contain key nutrients for fruit development. Additionally, when the leaves are attacked, the plant may not be able to produce enough energy through the process of photosynthesis. 

How to Make Tomato Fruit Bigger

Various tips will help you make the tomato fruit grow bigger.

1. Choose the Best Location for Your Tomatoes

When intending to transplant or plant tomatoes, choose a location with the best growing conditions within your garden. The spot should receive enough sunlight and be free from tall buildings and trees that may create shade. 

The area should also be accessible to a reliable source of water for irrigation. Tomato plants will give you bigger fruits when the growing conditions are ample. The plant requires sufficient sunlight, nutrients, and water to produce high-quality fruits.

2. Water Your Tomatoes Evenly and Deeply

A drip irrigation system is recommended for watering tomato plants evenly and deeply. It ensures the water is delivered at the base of the plant near the roots. There is also a reduced chance of water becoming in contact with the leaves. 

Water your plants early in the morning, which allows water to soak into the soil before evaporation sets in when the sun is out. Refrain from watering at night, especially when using a method that spills some water on the leaves.

3. Help Pollinate Your Tomato Plants

Help in pollinating your tomatoes, especially if you are growing them in a greenhouse. Lack of vents can prevent pollinators from reaching your plants. Shaking the plant gently or using an electric toothbrush to simulate the buzzing effects of bumblebees can help to literally dislodge the pollen grain from the male part of the flower. 

4. Choose Indeterminate Tomato Varieties

If you want tomatoes to produce large fruits, then you can go for indeterminate varieties. Determinate produces relatively smaller fruits as compared to indeterminate. Some of the indeterminate varieties that will give you bigger fruits include Black Cherry Organic, Juliet, Yellow Brandywine, and Cherokee Purple Organic. 

Not only do indeterminate varieties yield large fruits, but they also produce fruits throughout the season.

5. Prune Your Tomatoes

Prune your tomatoes for bigger fruit and a healthier plant. Other than large tomato fruits, pruning also helps to keep the plant smaller and compact, ensures the plant leaves and fruits are off the ground away from pests and diseases, improves air circulation, makes the fruit more flavorful, and allows the tomatoes to ripen early.

When pruning your tomatoes, ensure to leave 1 to 4 strong stems, cut the leaves that are near the ground, keep the plant to a manageable size, and remove the leaves that shade other leaves. Avoid cutting off the leaves that are above the fruit cluster to protect them from sunburn.

6. Mulch your Tomato Plants

Mulch your tomatoes immediately after transplanting using sawdust, straw, dried grass clippings, or shredded leaves. The layer of mulch should be at least 2 inches thick. Mulching has numerous benefits that will help to make tomato fruits grow bigger.

Apart from suppressing the weeds and conserving soil moisture content, mulching also helps to prevent soil-borne diseases like blight and septoria leaf spots. Since the spores of these diseases are found in the soil, mulching helps to prevent rainwater from splashing the spores onto the leaves.

7. Shelter Your Tomatoes from High Temperatures

Shelter your tomatoes from extreme temperatures to prevent them from producing small fruits.  If they are in containers, move them to a shade when the temperature rises above 90 degrees Fahrenheit. Create a temporary shade for tomatoes planted in the ground.

8. Control Pests and Diseases

Tomato plants are prone to various diseases that can cause poor production. Some of the diseases can be controlled by pruning the plant to keep it off the ground and improve aeration, mulching to prevent rainwater from splashing the spores of these pathogens onto the foliage, and uprooting and destroying the affected plants.

On the other hand, you can eradicate small pests like aphids by using an organic spray. Pick and kill large pests like cutworms and hornworms. 

9. Stake or Cage your Tomatoes

Prepare the stakes or cages before transplanting your tomato seedlings. Vertical support structures help the plants to grow in an upward posture. It also prevents the leaves and the fruits from becoming in contact with the soil. This gives your tomatoes enough room for growth and proper fruit formation.

Final Thoughts   

Now that you know what causes small tomato fruits and how to make them grow bigger, it’s time to roll up your sleeves and head back to the garden. If you get disappointed this season, remember that there is always the next season. Keep on trying until you achieve a bountiful harvest.