Temperature extremes most often causes tomatoes not to ripen.

Just when you begin admiring that big, beautiful crop of tomatoes growing in your garden, along comes a conundrum: the plants are set about with large, round, shiny green fruits, just waiting to turn red. Just waiting. And waiting. And waiting . . .

In almost every case, failure to ripen is caused by temperature. When temperatures fall below 50 degrees F, especially after a warm spell, the entire tomato plant slows down its growth. Heat is a growth trigger for this vegetable, and it won’t start up again until the weather warms up. You can give it some nice mulch and put a Kozy-Coat around the plant , but the best solution is simply time.

The opposite problem also stops the ripening process. When garden temperatures exceed about 90 degrees F, day after day, your tomato plants will stop producing carotene and lycopene, two of the chemicals critical to the turning those green fruits red.

While low summer temperatures will probably rise, super-high temperatures might not go down for a while. So, what can you do? Well, first let’s look at what NOT to do:

• Don’t give the plants more sun. This can lead to sunscald and has no effect on ripening.
• Don’t feed the plants any extra. It does no good.
• Don’t remove the leaves around the fruit.
• Don’t pop the green fruit into the fridge.

So, what is the solution? If it looks as if there’s no end in sight for these temperatures — or if you fear pests will eat your tomatoes before you can — you might try picking them and ripening them indoors. Here’s how to do it:

• Choose only soft, full-size green tomatoes. Most tomatoes naturally stay green for up to 3 weeks, so be sure that yours are fully ripe before picking.
• Place 3 to 5 tomatoes side by side (not stacked) in a paper bag. Roll up the top of the bag to loosely close it, and let it sit at room temperature (about 70 to 75), in darkness.
• Check the bag every other day, removing each tomato as it turns red.

Of course, another alternative is to fry your green tomatoes. But if you’re like us, nothing beats the sight of a beautiful deep red, homegrown tomato we know by name. Happy growing!