Posted on 28 January 2011 by

The Forever Green Tomato

By Mindy McIntosh-Shetter

The other day, my husband came home from work and said the tomatoes were not ripening.

His place of employment raises fresh vegetables that they in turn service to their employees.

The problem, it seemed, was that there were over 50 tomato plants sitting there with only green tomatoes and the tomatoes had been green for over one month.

The mystery widened when only 10 miles away, tomatoes were ripening on the vine in the Charlestown Community garden. To help explain what was going on started with the biology of a ripening tomato.

Tomatoes go through a developmental process or maturation.

During this time, several stages occur before a tomato is ready to eat. The early stages of this process involve the tomato increasing in size while remaining green. This part of the process takes 40 to 50 days.

Once the mature size or what is better known as “mature green” has been reached for that particular variety, it is time for the pigment to begin to change. The color will go from green to light green and then to the particular color of the cultivar, which includes pink, yellow, red or orange.

Ripening is then triggered by two factors, which include temperature and the presence of ethylene. The optimum temperature for ripening “mature green” tomatoes is 68 F to 77 F degrees. Straying from the optimum for long periods of time can cause the ripening process to stop.

Temperatures too hot or above 85 F degrees will prevent the tomatoes from producing lycopene or carotene. Both of these are needed to create that ripe tomato color. When this happens, the fruit will turn yellowish green to yellowish orange.

Once temperatures lower, ripening will continue but what happens if it is late in the season. The answer is to ripen them artificially. To do this begins with the selection of the tomatoes. Tomatoes that are in the immature green stage will never ripen off the vine. Instead look for tomatoes that are at the “mature green” stage with a little blush to them. Pick them and line them up, single level, in a tray. Store tray at 60 F to 65 F degrees or higher until ripe.

If you are picking the “mature green” tomatoes to just speed up the process when it is halted, leave the immature tomatoes alone. If you are picking the tomatoes before a killing frost, leave the immature tomatoes on the vine and place the vine in the compost bin.

So until we blog again, all good things will come to those who wait but sometimes good things need a little help.

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