Why Aren't My Tomatoes Ripening?
Steve Reiners, Co-Team Leader, Cornell University
Eastern New York Commercial Horticulture

So what's happening? It takes six to eight weeks from the time of pollination until tomato fruit reach full maturity. The length of time depends on the variety grown and of course, the weather conditions. The optimum temperature for ripening tomatoes is 70 to 75F. When temperatures exceed 85 to 90 F, the ripening process slows significantly or even stops. At these temperatures, lycopene and carotene, pigments responsible for giving the fruit their typical orange to red appearance cannot be produced. As a result, the fruit can stay in a mature green phase for quite some time.
Light conditions have very little to do with ripening. Tomatoes do not require light to ripen and in fact, fruit exposed to direct sunlight will heat to levels that inhibit pigment synthesis. Direct sun can also lead to sunscald of fruit. Do not remove leaves in an effort to ripen fruit. Also, soil fertility doesn't play much of a role. We do know that high levels of magnesium and low levels of potassium can lead to conditions like blotchy or uneven ripening or yellow shoulder disorder. But the slowness to ripen is not likely due to soil conditions and adding additional fertilizer will do nothing to quicken ripening.
If you absolutely cannot wait, some growers will remove fruit that are showing the first color changes. These fruit, in the a mature green or later phase, could be stored at room temperature (70-75F) in the dark. A more enclosed environment would be best as ethylene gas, released from fruit as they ripen, will stimulate other fruit to ripen. If temperatures remain high outdoors, these picked fruit will ripen more quickly, perhaps by as much as five days. As far as flavor, the greener fruit should develop flavor and color similar to what you would get if field ripened. The key is picking them when they are showing the first signs of ripening (no earlier) and keeping them at room temperature. Do not refrigerate, as this will absolutely destroy their flavor.


Upcoming Events
Managing Soil Nitrogen in Winter High Tunnels
March 5, 2021
To meet the year-round demand for locally produced food, vegetable farmers have embraced protected agriculture to extend their growing season, improve yields, and enhance crop quality. However, a statewide survey found that after several growing seasons, farmers struggle to maintain productivity due to challenges in long term soil health and fertility management. Cornell Cooperative Extension is exploring practices that high tunnel growers can adopt to better manage soil fertility and improve soil health.
Grab your lunch and join us for a virtual conversation on Friday, March 5, 2021 from 12:00pm - 1:30pm to hear our project updates and research results.
Assess and Prevent Food Safety Risks in Leafy Greens Production
March 18, 2021
This training will provide an overview of possible sources of contamination related to soil amendments, wildlife, water, post-harvest handling, transportation and more. This training will emphasize specific risks that leafy greens growers may experience, identify tangible corrective actions that can be taken, and provide participants the opportunity to work through example scenarios as a group.
2021 NYS Dry Bean Meeting

March 19, 2021
Join the us for the annual Dry Bean Meeting! There will be presentations covering the latest research in NY dry beans. Topic areas include market updates, white mold management, Western bean cutworm and soybean cyst nematode management, herbicide resistance management, dry bean variety testing, and incorporating NY dry beans into schools. This meeting is sponsored by Genesee Valley Bean Company, and Bayer CropScience.