Ripening those green tomatoes

Jayneandd/Flickr

Jayneandd/Flickr

Some years, the homegrown tomato harvest comes in late – very late. A good deal of our summer was cooler than usual, especially at night, which is not the preferred scenario for our favorite backyard crop.

Many gardeners are looking at plants with loads of tomatoes that are stubbornly, resolutely green. With first frost looming but four or five weeks off, what can you do? It turns out there are tactics to kick-start tomato plants into ripening their fruit, so listen up.

The first strategy can be undertaken around the end of August when you first have the chilling premonition that you will end the season with an abundance of unripe fruit and little joy. This involves directing the plant’s attention to ripening mature fruit instead of frittering away its remaining life on producing more shoots, more flowers and more itty bitty marble-sized tomatoes.

As a first step, remove any new flowers that form and “top” the plants, nipping off the uppermost terminal shoots. Get rid of those pathetic little tomatoes, too, since they haven’t a prayer of reaching eating size, let alone ripening before frost.

This sort of pruning may not be enough here in late September. It’s now time to ramp up the persuasion with a little creative torture. The idea is to stress the plant, leading it to believe it may perish. The threat of imminent demise prompts plants to hasten the development of the next generation, i.e., seeds, which are preceded by the maturation of the seed case, i.e., fruit.

First, withhold water. You don’t want the plants to expire from thirst, but stop treating them to a daily drink. Water only as needed to keep to plants going and let them dry out some between irrigations (rain we can do nothing about).

Next, root prune. Measure about eight inches out from the main stem and plunge your spade into the earth on three sides of the plant, leaving the fourth side intact. Reports are that this technique, popularized in Dick Raymond’s book “The Joy of Gardening,” works on plants with full-sized tomatoes that just won’t ripen.

Should this gambit fail and frost threaten, there is always the fall-back tactic of indoor ripening.

One method is to rip the entire plant out of the ground and hang it upside-down in a cool, frost-free place like a basement or garage. The fruit should ripen, but you might want to check the plant often lest your red, ripe beauties fall from the stem and go splat on the basement floor.

The other method is to pick mature fruits, wrap them individually in newspaper and wait, generally about two weeks. You can hasten ripening by putting the tomatoes in a paper bag with a ripe apple or banana, which will produce the naturally-occurring gas known as ethylene.

Off-the-vine ripening only works for tomatoes that are showing signs of pink or red, or are at the “mature green” stage where the skin has turned from a uniform mid-green to a light or whitish green. If you are in doubt, cut into one tomato; mature green fruit has seeds encased in gel and no empty cavities.

Please note that direct sun is neither required nor especially helpful, so a sunny window sill is actually not the best place for your tomatoes. Warmth is the crucial factor, with temperatures of 65 to 70 degrees about optimal, and cooler temperatures slowing down the process.

So, there’s your last hope. Let’s get after our tomato plants and urge them toward the finish line. After all, we’ve spent the whole summer season longing for that perfect, succulent tomato. May it not be in vain.