5 Reasons Why Tomatoes in Your Garden Bed Don't Turn Red

Are your tomatoes in the garden bed refusing to turn red this season? There might be some culprits, but there are also some simple fixes!

After a long growing season, ripe red tomato vines can be a satisfying and delicious reward. It can be frustrating to see your hard work not paying off when your tomato plants don't ripen as they should after months of planting, watering, and overall garden care. If you're wondering why your tomatoes aren't turning from green to red this season, there may be several factors at play.

Continue reading to learn why your tomatoes aren't turning red.

1. Too Hot

Depending on the tomato variety you're growing and the climate conditions, tomatoes take about 20 to 30 days from flowering to reach full size. It takes another 20 to 30 days for them to turn from green to red.

If you notice that your tomatoes fail to ripen during this period, extreme high temperatures might be the issue.

The ideal temperature range for ripening is between 68 to 77 degrees Fahrenheit.

Maturity stops in prolonged extreme heat.

Maturity cannot occur above 85 degrees Fahrenheit because the transformation from green to red, and the production of tomato lycopene and carotenoid pigments, cannot take place at high temperatures.

If you see the end of a heatwave in the forecast, leave the tomatoes on the vine and wait for them to ripen. If the high temperatures are expected to continue, harvest the tomatoes and bring them indoors to complete ripening.

If your tomatoes turn pale green or blush, take them off the vine and store them in a dark, enclosed area indoors. Green tomatoes take five days to two weeks to ripen at temperatures between 70 to 75 degrees Fahrenheit.

2. Too Cold

Just as tomatoes can't ripen in high temperatures, they are also sensitive to colder temperatures. If your tomatoes show blemishes or fail to turn red, cold weather might be the culprit.

Daytime temperatures below 60 degrees Fahrenheit and nighttime temperatures below 50 degrees Fahrenheit can result in underripe or poorly developed fruits.

If you anticipate a cold snap at night, be sure to cover the tomatoes. Depending on your covers, it can typically provide 3 to 5 degrees Fahrenheit of insulation, helping to withstand low temperatures.

Good choices for tomato covers include commercial frost blankets, floating row covers, or even plastic sheets. Ensure that the covers don't touch your plants as it can cause freeze damage.

If your tomatoes are too cold to continue growing outdoors, harvest them early and bring them indoors, similar to the situation with high temperatures.

Remember to store them between 65 to 70 degrees Fahrenheit. Tomatoes are sensitive to cold damage even after harvest, so keep them out of the refrigerator. If stored at temperatures below 60 degrees Fahrenheit for more than two weeks, they won't develop the vibrant red color you desire.

3.Potassium Deficiency

Tomatoes require high levels of potassium during the growing season. Potassium ensures high yields, quality fruits, and proper ripening of your tomatoes. If you notice spots or yellowish ripening instead of the desired red, potassium deficiency might be the issue. This lack of color and yellowing of fruits is known as "yellow shoulders" and occurs when the shoulders of the tomato discolor around the stem.

Take a look at the growing conditions for your tomatoes. There are various factors that can affect your tomatoes' ability to receive the necessary amount of potassium. For example, if your soil is waterlogged or poorly drained, it may prevent your tomato plants from obtaining an adequate amount of potassium.

To correct waterlogging, add organic matter to the soil, such as compost. Compost contains rich nutrients that can work wonders for your soil, reducing water density, and improving soil health and structure.

There are also organic fertilizers with high potassium content that you can add to your soil. Wood ash, coffee grounds, and banana peels are all good choices.

4.Excessive Nitrogen

While nitrogen is a nutrient responsible for producing green leafy vegetables in many plants, it is not always a good thing. Take tomatoes, for example. While they are heavy feeders, if they are over-fertilized with excessive nitrogen in the soil, their response is not favorable. Too much nitrogen hinders the plant's ability to produce fruits and vegetables and instead directs its energy towards leaf growth.

If you notice that your plants are producing lush, dark green leaves but the tomatoes fail to grow or turn red and ripen, excessive nitrogen might be the cause.

To avoid this situation, be cautious not to apply nitrogen fertilizers.

A good guideline is to use a fertilizer with a balanced NPK (nitrogen, phosphorus, and potassium) formula, such as 20-20-20, two weeks after planting.

After the tomato plants start flowering, switch to a high-potassium fertilizer where the nitrogen content is no more than three times the phosphorus or potassium level. For example, use a formula like 9-15-30.

If the damage has already been done and there is too much nitrogen affecting your plants, apply sawdust to the soil. When sawdust decomposes, it heavily relies on nitrogen and helps absorb it from the soil.

Remember to conduct soil testing to read the nutrient levels and requirements of your soil most accurately.

5.Slow Ripening

One of the wonderful things about tomatoes is that there are many different varieties to choose from, each offering unique sizes, colors, and flavors. Early varieties can be harvested in less than 70 days. "Stupice" and "SubArcticPlenty" are varieties that won't waste time in your garden, taking around 50 days to harvest.

Mid-season varieties take 70 to 80 days to harvest. Varieties like "Celebrity," "Carmello," and "Fantastic" only require 70 days for harvesting.

Lastly, late-season varieties take over 80 days to harvest. "Chadwick Cherry" is a variety that takes 90 days to harvest, as well as "Brandywine" and "Indigo Rose."

If you have a mix of these different tomato plant varieties in your garden, you'll find that some ripen faster than others, sometimes by almost a month. If that's the case, be patient with your late-season varieties as they just need a bit more time to grow.

Happy Harvesting!

If your tomatoes are having a hard time turning from green to red this season, don't give up! While some factors may affect the ripening process, all hope is not lost. With a bit of investigation, you'll likely find the root cause of the problem and get your tomatoes back on track for the remaining season.