The Top 5 Reasons Tomatoes Won’t Turn Red or Ripen

It’s incredibly frustrating to see your tomato plants thriving, only to have their fruits stubbornly remain green. Unfortunately, wishing and hoping won’t speed up the ripening process. Here, we explain the hard truths and provide solutions for when your tomatoes won’t turn red.

What Causes Tomatoes to Turn Red?

The red color of tomatoes is due to lycopene, a natural pigment and antioxidant that accumulates in the fruit as it ripens under certain conditions. Lycopene not only makes the fruit visually appealing but also indicates it is packed with vitamins and nutrients. The balance between the chemical makeup and genetics of the tomato variety, as well as environmental factors like temperature and rainfall, are crucial for producing that perfect red hue.

5 Reasons Tomatoes Won’t Turn Red

1. Fluctuating Temperatures

Tomatoes require temperatures between 70 and 75 degrees Fahrenheit to ripen. Temperatures above 85 degrees or below 50 degrees can halt the color change, stopping the ripening process and preventing the tomato from maturing.

What To Do:

•    Provide shade for plants during heat waves.
•    Use row covers to retain warmth during cooler nights.
•    Wait for temperatures to stabilize.

2. Young Immature Fruit

Tomatoes must reach their full mature size before they start to ripen. It’s essential to research your tomato variety to understand the number of days it takes for a mature fruit to form. Patience is crucial, as tomatoes will only begin to change color once they’re fully developed.

What To Do:  Research your tomato variety, whether it’s determinate or indeterminate, and how long it takes to produce harvestable fruit.

3. Lacking Proper Sunlight

All tomato varieties need full sun, with at least 6 hours of direct sunlight daily. Dense foliage shading the maturing tomatoes or planting in heavily shaded areas can reduce the energy needed for tomatoes to turn red.

What To Do:

•   Plant tomato plants in areas with at least 6 hours of direct sunlight daily.
•   Prune any leaves that block sunlight from reaching the fruit.
•   Reposition container plants or add reflective surfaces if necessary.

4. Improper Soil Nutrients

The right nutrient balance in the soil is essential for tomatoes to flourish. Too much nitrogen causes the plant to focus on producing leafy green foliage rather than plump red tomatoes, while too little nitrogen leads to stunted growth and yellowed leaves. Balanced fertilizer with the appropriate mix of nutrients supports flower and fruit production. Look for a fertilizer with a 5-10-5 or 10-10-10 ratio, representing nitrogen, phosphorus, and potassium (NPK).

What To Do:

•  Test your soil to ensure it has the proper, balanced nutrients.
•  Use high-quality fertilizers

5. Lack of Pruning**

Tomato plants with excessive leaves, stems, or fruits can struggle to allocate their energy efficiently. They may prioritize growing more leaves and stems, delaying the ripening process.

What To Do:

•  Remove suckers, the small shoots that grow in the joint between the main stem and a branch of a tomato plant.
•  Trim back 20 percent of the plant to allow more sunlight and reduce energy expenditure.
•  Remove small, immature fruits so the plant can focus on ripening the more mature tomatoes.

Tips from the Pros

Be Patient

Gardening often teaches us the value of patience. Luckily, you can research tomato varieties with shorter harvesting times to avoid long waits for a delicious vine-ripened tomato.

Quick Ripening Varieties Include:

• Sakura (Organic): Matures beautiful fruits in 55 days.
• Early Girl: Produces mature fruits in 57 days.
• Sun Gold: Supersweet and matures in 65 days.

Pay Attention to Weather Patterns

Weather is unpredictable and can affect the growing and ripening process. Extreme heat can inhibit the production of lycopene, the red pigment, while cooler temperatures can slow development.