Why Aren’t My Tomatoes Turning Red? A Comprehensive Guide to Troubleshooting Tomato Ripening Issues

by Jasmine February 1, 2026

written by Jasmine February 1, 2026

Why Aren’t My Tomatoes Turning Red? 7 Possible Reasons

Understanding Tomato Ripening

When tomatoes reach their full green size, they undergo a ripening process that involves the production of lycopene, the pigment that gives them their red color. This process is triggered by a natural hormone called ethylene.

Temperature

Temperature plays a crucial role in tomato ripening. Ideal temperatures range from 68 to 77 degrees Fahrenheit. Temperatures above 85 degrees inhibit lycopene production, slowing or even halting ripening. Conversely, temperatures below 60 degrees can also delay ripening.

Sunlight

While tomatoes need sunlight for growth, too much direct sunlight can hinder ripening. The heat generated by intense sunlight can raise temperatures to levels that inhibit lycopene production. Pruning leaves away from mature tomatoes to increase sun exposure can also cause sunscald and cracking.

Water

Tomato plants require regular watering, but excessive watering can slow down ripening. Once fruits reach their mature size, reducing or stopping irrigation can stress the plant and trigger survival mode, redirecting energy towards ripening to produce viable seeds.

Nutrients

Tomatoes need a balanced supply of nutrients, including phosphorus and potassium, which are essential for lycopene production. Insufficient phosphorus and potassium can result in slow or uneven ripening. Fertilize plants with a fertilizer higher in phosphorus, such as NPK 5-10-5, when the first small fruits appear.

Nitrogen

While nitrogen is important for tomato growth, excessive nitrogen can hinder ripening. Fertilizing with a product that contains too much nitrogen can divert energy towards foliage growth, slowing down fruit ripening. Once mature fruits are on the vine, withhold fertilizer and allow natural ripening processes to occur.

Pruning

Pruning tomato plants by removing early suckers redirects energy towards fruit production and ripening. Overloaded vines or vines with unproductive suckers can struggle to produce ripe tomatoes. Early pruning promotes higher quality fruit that ripens more easily and quickly.

Variety

It’s important to note that different tomato varieties ripen to different colors, including shades of red, orange, pink, purple, and even striped. If you’re waiting for your tomatoes to turn red, check the seed package for the expected color of the ripe fruit.

Additional Tips

Check your seed package for the estimated harvest time for your tomato variety, as different varieties have varying ripening periods.
If green tomatoes have reached their full size, they can be ripened off the vine in a warm indoor location.
Small, hard, underdeveloped green fruits are unlikely to turn red and should be composted.
Avoid over-fertilizing, as excessive nutrients can harm the plants.
Regularly monitor plants for pests and diseases that can affect ripening.
Harvest tomatoes when they are fully ripe and slightly soft to the touch.

Jasmine

Jasmine's journey began with a camera in hand and a heart brimming with stories. The world, for her, wasn't just a collection of sights and sounds; it was a vibrant tapestry woven with intricate details, each one waiting to be captured and explored. This inherent curiosity naturally led her to the written word, where she discovered the power of language to weave narratives that resonated with the soul. Jasmine's articles in LifeScienceArt's life section are a testament to this synergy. Her words dance across the page, painting vivid pictures that transport readers to the heart of the experience. Whether it's the quiet contemplation sparked by a morning sunrise or the electrifying energy of a bustling city street, Jasmine has an uncanny ability to translate the essence of a moment into words that resonate. But Jasmine's talents extend far beyond the written word. With a keen eye for detail and a photographer's soul, she sees the world through a unique lens. Her photographs are more than just snapshots; they're windows into hidden emotions and unspoken narratives. A single image, captured with Jasmine's signature touch, can evoke a kaleidoscope of feelings, prompting introspection and igniting a sense of wonder in the viewer. The way she plays with light and shadow, or the way she finds beauty in the ordinary, speaks volumes about her artistic vision. It's clear that Jasmine doesn't just see the world; she feels it, deeply and passionately. This depth of feeling is evident in her writing as well. Jasmine's articles are infused with a raw honesty that connects with readers on a personal level. She doesn't shy away from exploring the complexities of life, the joys and sorrows, the triumphs and failures that we all experience. But even when tackling difficult topics, there's an underlying optimism in her words, a belief in the inherent resilience of the human spirit. Jasmine's writing encourages readers to embrace the full spectrum of life's experiences, to find beauty in the unexpected, and to navigate the challenges with courage and grace. One gets the sense that Jasmine's own life is a continuous exploration, a constant search for new experiences and perspectives. Whether it's venturing off the beaten path to capture a hidden gem through her lens or delving into the depths of human emotion through her writing, Jasmine thrives on the journey itself. This inherent sense of adventure is infectious, inspiring readers to embark on their own explorations, both internal and external. Jasmine's work isn't just about capturing moments; it's about igniting a spark of curiosity and a desire to live life to the fullest. Perhaps the most captivating aspect of Jasmine's work is the sense of intimacy it evokes. Reading her articles feels like having a conversation with a close friend, someone who understands the nuances of life and isn't afraid to share their vulnerabilities. This ability to connect with readers on a personal level is what makes Jasmine's writing so powerful and enduring. It's a testament to her own authenticity and her genuine desire to connect with others through the magic of words and images.