Updated: Oct 21, 2020
Growing tomatoes in zone 3 Alberta never fails to leave me with needing to pick many of my tomatoes while they are still green come fall when the cold of winter is suddenly about to descend upon us! I have had amazing success with ripening nearly all of my green tomatoes and want to share with you the tomato ripening secrets I have learned.
Tomatoes will not ripen on the vine if the daytime temperatures are below 15°C (60°F) for 14 consecutive days. Knowing this, a better choice may be to pick your green tomatoes while they are still green and bringing them indoors to ripen.
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There are many incorrect myths on how tomatoes ripen. Lets take a look at some of them.
Fiction - Tomatoes need sunlight to ripen. Fact - Sunlight does not in fact assist in the ripening process of tomatoes. It may even cause them to rot and be detrimental.
Fiction - Tomatoes ripen better on the vine. Fact - Tomatoes ripen just as quickly when picked off the vine.
Fiction - Tomatoes taste better when ripened on the vine. Fact - Studies have found there is no discernible taste difference to tomatoes ripened on or off the vine. The reason your garden tomatoes taste so much better than store bought is the same for all your garden produce, it is likely grown in soil with more natural nutrients and sunlight than the store bought counterpart.
An important factor that does come into play when ripening your green tomatoes is the ripening hormone ethylene. Ethylene is naturally produced by ripening fruits such as apples, bananas and tomatoes. Some fruits on the other hand, such as grapes, do not produce this hormone. Ethylene production is why a whole bunch of bananas will ripen at the same time, or a whole apple tree will ripen right around the same time. The production of the ethylene by ripening fruit signals fruit around it to also ripen. For this reason it is believed that placing a ripe apple or banana in a mostly sealed box with green tomatoes will signal the tomatoes to ripen sooner than they otherwise would.
I use this method and have found it works very well. I place my green tomatoes in a 3 to 4 inch layer inside a box lined with newspaper (the newspaper is there to absorb any moisture) and an apple in the middle. I try to choose a box that has a couple holes in it so there is some air ventilation and available oxygen. Tomatoes ripen best between 20°C (68°F) and 25°C (77°F), so I keep the box inside the house. I find after the first week I am finding ripe tomatoes every 2 days! I like this method because it keeps me in a constant supply of garden fresh tomatoes for around 6 weeks into the fall!
If you have enjoyed this blog post I suggest you also read 10 Proven Tips for Growing Tomatoes to learn tips and tricks on growing your tomatoes from seed! For more gardening tips suscribe to my blog (the bottom of the home page) and follow me on Pinterest, Instagram, Facebook and YouTube.
Articles used for research on this topic include https://homeguides.sfgate.com/cold-temperatures-keep-tomatoes-ripening-cold-be-79457.html and https://ufdcimages.uflib.ufl.edu/IR/00/00/46/98/00001/CV20600.PDF