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Why Do Tomatoes Ripen Unevenly

Most gardeners will experience an issue with a crop that won’t ripen the way it’s supposed to. Maybe it’s blotchy, multicolored, or even stuck at an odd color. Tomatoes are notorious for doing this. They commonly appear in two different colors simultaneously, which can often be an issue with the ripening process. If you are experiencing this problem with your tomatoes, you are most likely wondering, why do tomatoes ripen unevenly?

Tomatoes ripen unevenly because of inadequate growing temperatures, an excess or lack of certain nutrients like potassium and nitrogen, and insufficient maintenance of the plants. Tomatoes are pretty specific with their growing needs, and failing to adhere to all the necessary steps of growing tomatoes can hinder the ripening process.

If you’ve experienced uneven ripening with your tomatoes and want to prevent it, continue reading. 

Reasons Your Tomatoes Aren’t Ripening Evenly

  • Temperature- Tomatoes ripen from a green stage most efficiently at a temperature of around 68 to 77 degrees Fahrenheit. Temperatures any colder will slow the process down. Temperatures any higher can restrict the carotene and lycopene production, preventing the tomatoes from turning bright red. Any temperature outside of the ideal growth range can cause uneven ripening. 
  • Over Fertilizing- Tomato plants only need to be fertilized two to three times during the growing season. Excess fertilizing, especially with too much nitrogen, can cause uneven ripening or a lack of ripening. Tomato plants need a particular amount of nitrogen, and if they receive too much, they will dispose of the excess through the production of new leaves and stems, which takes the energy and focus of the plant away from ripening the fruit. 
  • Lack of potassium- Potassium is one of the critical components in ripening tomatoes. With insufficient amounts, tomatoes can become blotchy and discolored, with some ripe areas and some unripe ones. Choose a fertilizer that has an adequate amount of potassium in it along with a well-rounded soil. 
  • Failure to harvest- It’s possible to miss or forget to pick fruit that has become fully ripe. In doing so, your plants won’t be able to focus their energy on ripening the fruit that needs it most, causing uneven ripening.

How Do You Redden Blotchy Tomatoes?

If you have tried many different techniques to ripen your tomatoes fully and still aren’t having any luck, consider harvesting them. To ripen fully, tomatoes don’t necessarily need to be attached to the vine. Try placing your tomatoes indoors into an enclosed container of some sort. Paper bags, cardboard boxes, Tupperware, or even a kitchen drawer are great options.

Ensure there is plenty of room between each of your tomatoes to allow secretion of moisture and prevent molding. If you want to speed up the process, add a banana or apple to the collection of tomatoes. They give off ethylene gas which will trap itself with the tomatoes and help ripen them faster. 

What Is Yellow Shoulder Disorder?

Yellow shoulder disorder is a condition that prevents the top of tomatoes from turning red. Instead, they will be a yellow or even light green color while the rest of the tomato is red. This can be interpreted as uneven ripening, but it’s an internal issue with the fruit.

Sadly, that area of the tomato will most likely have a bland taste, and it won’t possess the vitamins that the rest of the tomato does. There isn’t a cure for yellow shoulder in your tomatoes, and there are only a few ways to prevent it. If you are experiencing uneven ripening and you’ve tried many different techniques to ripen your tomatoes fully, they most likely have yellow shoulder disorder. 

How to Prevent Yellow Shoulder Disorder

  1. Keep your tomatoes out of high heat. Warm temperatures, specifically over 77 degrees, can cause yellow shoulder disorder. If your tomatoes are receiving at least 6 hours of sunlight a day, shade them with cover to prevent them from receiving too much sunlight, especially at the hottest part of the day. 
  2. Practice crop rotation. Tomatoes can’t be grown in the same soil every year. Old soil may not contain the necessary nutrients to keep your tomatoes from becoming yellow-shouldered. 
  3. Test your soil. You can go to your local home and garden store or even order a test kit online. A test kit will show you if your soil’s pH levels are good enough. Tomatoes thrive at a level no lower than 6.0 and no higher than 6.8. Having a blanched pH level and the correct amount of nutrients will help prevent yellow shoulder disorder. 
  4. Use a balanced fertilizer. Use a fertilizer that is made primarily to fulfill the needs of tomatoes. Most Gardening stores will have fertilizers specific to tomatoes available for purchase. You can also search for them online. Tomatoes are heavy feeders, meaning they require large amounts of fertilizer to grow successfully. A good tomato fertilizer will ensure adequate nutrients if your soil lacks any. 

Last Thoughts

Overall, it is common for tomatoes to have issues ripening evenly. Try all the tips listed above, which include maintaining your crops properly through efficient fertilizers, growing in proper weather conditions (68-77 degrees Fahrenheit), and making sure your tomatoes don’t lack potassium or other nutrients.

If you don’t believe these methods are working, try harvesting your unripe or unevenly ripened tomatoes and bringing them inside to complete the ripening process indoors. Lastly, if nothing seems to be working, your tomatoes may have yellow shoulder disorder causing them to have yellow tops but be red everywhere else.

There is a list above to help prevent this disorder in your tomatoes. It includes using a shading mechanism, practicing crop rotation, testing your soil, and using good fertilizers. Of course, don’t be discouraged if you are experiencing uneven ripening or yellow shoulder disorder. They are both common issues, and there are many tips and tricks to help you. Tomatoes are a very rewarding crop to master.