Tomatoes are one of the most rewarding crops for gardeners. But it’s frustrating when they stay green and stubbornly refuse to ripen. If you’re wondering, “Why aren’t my tomatoes red?” — you’re not alone.
Tomato ripening depends on many factors including temperature, nutrients, and light. Let’s explore the top 10 reasons your tomatoes may not be turning red — and how to fix them.
1. Lack of Warm Temperatures
Tomatoes need consistent warmth to ripen. If the temperature drops below 55°F (13°C), ripening slows or stops completely. This often happens during early spring or late summer evenings. To help, use row covers or plant tomatoes in containers so you can move them indoors during cold nights. Choose fast-maturing or cold-tolerant varieties in cooler regions.
2. Not Enough Sunlight
Tomatoes require 6–8 hours of direct sunlight each day. Without enough light, the plant can’t produce enough energy to turn green fruit red. Make sure your tomato plants are in a sunny spot. Trim back nearby plants or branches that block the light. If sunlight is limited, try using reflective mulch to bounce more light onto the plants.
3. Excess Nitrogen, Low Phosphorus
Fertilizers high in nitrogen promote leaf and stem growth but delay fruit ripening. At the same time, phosphorus is essential for healthy fruit development and color. Switch to a fertilizer with lower nitrogen and more phosphorus, like a 5-10-10 mix. Avoid over-fertilizing throughout the growing season.
4. Overwatering or Inconsistent Watering
Too much water can cause roots to become soggy and limit nutrient absorption. Inconsistent watering leads to stress, slowing ripening. Water deeply once or twice a week and keep the soil consistently moist—not wet. Use mulch to help retain soil moisture and reduce watering frequency.
5. Slow-Ripening Tomato Variety
Some tomato varieties, especially heirlooms or large beefsteaks, naturally take longer to ripen—sometimes 80 to 100 days. This is normal. If you want quicker results in the future, plant smaller or cherry tomato varieties like ‘Sun Gold’ or ‘Roma’ that ripen faster.
6. Too Many Fruits on the Plant
When a plant is overloaded with green fruit, it spreads its energy across all of them, slowing the ripening process. Thin out smaller or excess tomatoes, especially later in the season, so the plant can focus on ripening the existing fruit more quickly.
7. Extreme Heat
When daytime temperatures go above 85°F (29°C), tomatoes can stop ripening altogether. The pigments that turn tomatoes red stop forming in high heat. During heat waves, provide shade during peak sun hours and water early in the day to reduce plant stress.
8. Poor Air Circulation
Dense, leafy growth traps humidity and slows ripening. It also increases the risk of disease. Prune excess leaves and suckers to let air move freely around the plant. Space plants at least 18–24 inches apart and use stakes or cages to keep them upright.
9. Low Ethylene Production
Ethylene is the natural gas tomatoes release to trigger ripening. Stressed or unhealthy plants may not produce enough of it. If your tomatoes are mature but not ripening, pick them and place them in a paper bag with a ripe banana or apple. This speeds up the process using natural ethylene from the fruit.
10. Pests or Disease
Pests like aphids and diseases like blight weaken the plant, causing it to divert energy from fruit ripening to survival. Regularly check for pests or leaf spots. Use neem oil or organic insect sprays as needed. Remove infected leaves and avoid wetting foliage when watering.
How to Ripen Green Tomatoes After Harvesting
When fall comes and temperatures go below 50°F, tomatoes won’t ripen on the vine. If your tomatoes have some color at the bottom and feel soft, they can ripen indoors.
Put the tomatoes in a place that is between 60 and 65 degrees. A pantry or basement is a good spot. Tomatoes don’t need sunlight to ripen. You can put them in a paper bag with an apple or banana. These fruits help tomatoes ripen faster because they release a gas called ethylene.
Another way is to pull up the whole plant and hang it upside down inside. Cut off extra leaves to make it easier. The tomatoes may ripen as the plant dries. Be sure to shake off the dirt from the roots before bringing it inside.
Learn about harvesting and storing your tomatoes here.
If you grow tomatoes in pots, move the whole plant indoors. Put it in a sunny spot to ripen the last tomatoes.
Interview with Director Juanita Wilson: The Making of Tomato Red
In this interview, director Juanita Wilson discusses her experience working on the film Tomato Red, based on the novel by Daniel Woodrell. She shares insights about the challenges of adapting the story and bringing it to the screen.
To learn more about the interview, you can read the full document here. Dr. J. Wilson and Dr. J. Buggle are credited in the document.
FAQs About Why Aren’t My Tomatoes Turning Red
Why Are My Tomatoes Still Green?
Tomatoes stay green if they don’t have enough time to ripen. They need steady warmth, between 68°F and 77°F, to turn red. Cold temperatures, especially at night, slow them down. Give your plants plenty of sun and warmth to help them ripen.
Can Overwatering Affect Tomato Ripening?
Yes, overwatering can stop tomatoes from turning red. Too much water makes the soil too wet, which blocks nutrients from reaching the plant. This slows down ripening. Water your tomatoes evenly, but not too much.
What Role Do Nutrients Play in Tomato Color?
Tomatoes need the right nutrients to turn red. If the plant doesn’t get enough phosphorus, it may stay green. Use a balanced fertilizer that gives the plant what it needs to grow and ripen.
How Does Sunlight Impact Tomato Ripening?
Tomatoes need sunlight to turn red. Sun helps the plant make energy and stay warm. Tomatoes should get 6 to 8 hours of sunlight each day. If they don’t get enough, they may stay green. Plant them where they can get full sun.
Final Thought
If the season is ending and frost is coming, pick tomatoes with a slight color blush and let them ripen indoors. Keep them in a warm, dark place for best results.
One Response