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.
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Upcoming Events
Storage Crop Facility School: Large-Scale Vegetable (Potato and Cabbage)
December 1, 2020
Speakers from across the Northeast will be presenting on challenges and updates surrounding large-scale potato and cabbage storage. Join us for this FREE online event to hear about storage innovation and updating facilities, decreasing storage diseases, storage funding programs, and farm food safety considerations for storage facilities.
Storage Crop Facility School: Smaller-Scale Mixed Vegetable Storage
December 8, 2020
Join us for this FREE online event to hear the latest information on smaller-scale storage and storage of mixed vegetables. Speakers from across the Northeast and Midwest will be presenting on cold storage construction, humidity and ventilation management, tactics for better storage of produce, decreasing diseases in storage, funding opportunities, and farm food safety considerations for storage facilities.
2020 NYS Processing Vegetable Advisory Meetings
December 15, 2020 : Snap Bean Advisory
Processors and growers of snap beans are invited to this FREE online meeting to review the 2020 season and comment on pests and other issues that were encountered. Reports of the 2020 research projects funded by the New York Vegetable Research Association/Council will be given. A group discussion period will include the review of research priorities for the coming year. 0.75 DEC credits in categories 1a, 10, and 23 will be offered.
December 15, 2020 : Green Pea and Sweet Corn Advisory
Processors and growers of green peas and sweet corn are invited to this FREE online meeting to review the 2020 season and comment on pests and other issues that were encountered. Reports of the 2020 research projects funded by the New York Vegetable Research Association/Council will be given. A group discussion period will include the review of research priorities for the coming year. 1.0 DEC credits in categories 1a, 10, and 23 will be offered.
December 16, 2020 : Beet and Carrot Advisory Meeting
Processors and growers of beets and carrots are invited to this FREE online meeting to review the 2020 season and comment on pests and other issues that were encountered. Reports of the 2020 research projects funded by the New York Vegetable Research Association/Council will be given. A group discussion period will include the review of research priorities for the coming year. 1.0 DEC credits in categories 1a, 10, and 23 will be offered.