I was wondering if anyone has thoughts on what could be preventing my...

Asked September 3, 2015, 2:05 PM EDT

I was wondering if anyone has thoughts on what could be preventing my tomatoes from ripening this year. I have been vegetable gardening for the past 12 years and have never experienced this problem. Over the years I have had some problems with blight so the last 2 years I have been applying a fungicide spray as recommended for tomato blight in the UofM extension's document- Early Blight of Tomatoes and Potatoes. This worked wonders last summer and I had a great tomato crop. This year we had some level of overspray from a soybean field nearby and for a few weeks the tomato plants did not look good, however they have since come back, filled out, bloomed and they have many green tomatoes. The two cherry tomato plants are producing a few, and a couple of the other plants yielded 2 red tomatoes each in late July. Since then none of the many green tomatoes are ripening. The plants continue to bloom, but none of the tomatoes are ripening. Is there a likely cause for this?

Carver County Minnesota

1 Response

There is no definite time frame for tomatoes to ripen. It depends on the temperature. Tomatoes ripen best at temperatures in the high 70s to mid 80s. The lower the temperature is from the ideal, the longer it will take a tomato to ripen. A slow, cool start in the late spring may have made the tomatoes a little later to develop. Avoiding excess fertilizer at this time will help with the ripening process. Just make sure they are getting the full 6 to 8 hours of sun the plants need so the fruit will ripen. If you want to go ahead and pick them, you can ripen tomatoes in well-ventilated, open cardboard boxes at room temperature checking them every few days to eliminate those that may have spoiled. Mature green tomatoes will ripen in 14 days at 70 degrees F and 28 days at 55 degrees F. Tomatoes may get mushy and not ripen well when temperatures are above 90 degrees F. Their optimum ripening temperature is 77 - 80 degrees F. During hot weather, you can try picking tomatoes when they have a pink color and let them ripen indoors. Tomatoes can also develop a mealy (mushy) interior if an abundance of water (heavy rain) fell when the tomato was ripening.

At this point in the summer you should remove any new flowers and small fruit that has no chance of ripening so the plant sends all the energy to the larger fruit. You should also be watering less often to help the plants shut down their fruit production.

I hope this is helpful. Please contact AaE again if you have further questions.