Got beautiful, perfectly shaped tomatoes that just don't want to ripen?
Here are some explanations of the tomato ripening process and what you can do to maximize your chances of having a mountain of red tomatoes by summer's end.
First of all, it is important to know that each variety of tomato will ripen at its own pace. Some are faster and some are slower. Opt for early varieties with a short growing season such as the Early Glacier or the Moskvich that ripen quickly to maximize your chances of having an abundance of red tomatoes.
Don't forget cherry tomatoes generally mature faster than larger ones. Don't lose hope for your big tomatoes when you see your little cherry tomatoes ripening!
When planting your seedlings out, make sure you take good care of them by following the instructions in our Planting Out Tomatoes blog post.
So, that covered, let's have a look at how tomatoes ripen.
How does a tomato ripen?
A tomato plant must produce lycopene and carotene to ripen its fruit. To do this, the plant must be in an environment that is between 10 and 29 degrees Celsius. A greenhouse that is too hot and the arrival of fall are two things that can slow down the ripening of fruit.
Only a mature tomato will begin to produce ethylene, a chemical compound that ripens fruit. It is during this stage that the fruit develops an aroma and the colour begins to change.
So a tomato will only start to change colour when it has reached maturity. Even with all the possible and imaginable tricks, any tomatoes that are not mature will not change colour or develop an aroma.
But how can you recognize a 'mature' tomato?
As you gain experience, you'll be able to simply see it. But if you're new to gardening, listen up. It's not easy to distinguish because you can't trust the size of the fruit. A mature tomato has a shiny green skin, its skin is smooth and very translucent; we can often see its small vessels through its skin. While an immature tomato is a bit paler, its surface is not as shiny and translucent as a mature tomato.
What to do before the first frost?
You can cover your plants with thick blankets the first nights of frost, but when daytime temperatures don't usually rise above 15C and it freezes overnight, it's time to harvest the remaining tomatoes.
To ripen your tomatoes indoors, simply pick all the mature green tomatoes on your plants and put them in a fairly warm place (between 15 and 29 degrees Celsius). Contrary to popular belief (apple or banana in a paper bag, blanket, top of a cupboard, in the dark, in the sun on a windowsill, under Grandpa's bed with a hot water bottle, etc.), if the fruit has finished growing and had reached the ripening stage, your tomatoes will ripen quietly in the warmth, simply placed in a tray on the kitchen table.
Finally, yes, immature tomatoes will eventually change color too, but their texture, range of taste and water content will be much lower than tomatoes that were mature when harvested. It is also possible to use them to make ketchup or add them through your recipes, just as you do with zucchini. As for the plants left in your garden, it's totally normal to have some tomatoes left on our plants at the end of the season - after all, most tomato plants are indeterminate and we do have a short growing season. But, nothing is ever lost, and there are some great recipes out there for cooking with green tomatoes.
The best thing to do is to start your season by choosing the best tomato varieties for our climate.