Late-season tomatoes can be a wonderful thing. But one of the biggest tomato frustrations for gardeners comes late in the season. When tomato plants are still loaded with green fruit and the first frost is looming, things can look bleak.

Tomatoes need warmth to ripen. As autumn days shorten and temperatures drop, the process slows down significantly. It creates a tricky situation. Waiting can be risky, because a single frost can cause a lot of damage. It can even destroy all that fruit you’ve been caring for so diligently.

You have to ask yourself a few important questions. How long do you have before frost becomes a possibility? If it’s not long, do you leave the fruit on the vine, hoping for just a few more sunny days? 

The situation accentuates the gardener’s yearly struggle with timing and the unpredictable nature of nature. Your choice often comes down to flavor and preservation. 

Vine-ripened tomatoes develop the richest taste. However, the danger of frost may compel a gardener to pick them while they’re still green. Let’s discuss some ways you can expedite the ripening process, so you’ll have delicious tomatoes before that first frost hits.

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Reduce Watering

Slightly reducing water nudges fruit toward full color.

A simple way to speed tomato ripening in the fall is to slightly reduce watering. A small to moderate reduction in moisture will induce stress in your plants. When the plant feels stress, it will shift energy away from new growth into ripening the fruit that already exists. 

The reason it does so is a survival strategy. The plant reacts to stress by attempting to set seeds. In order for the seeds to ripen, the fruit must also. Now, don’t cut back too much, because tomato plants need moisture. 

If you cut back too much and then experience heavy rain, your tomatoes will crack. The fruit shrinks and expands with moisture. So, when it goes from dehydrated to suddenly overhydrated, the inside bursts out of the skin. Just reduce it by a mild to moderate amount.

Thin Excess Foliage

Selectively thinning foliage improves air and light exposure.

Thinning excess foliage is another effective way to speed tomato ripening.  It’s particularly effective nearing the end of the season. Tomato plants produce a lot of leafy growth. Too much of it can cast a shadow on the fruit. When the fruits sit in the shade of the foliage, they stay cooler, which slows the ripening process. 

You can selectively prune the larger leaves, particularly the ones that are casting shade on your fruit. This allows light to reach your tomatoes, and the light and warmth speed up the ripening process. 

The reason increased sunlight helps ripen your tomatoes faster is that it speeds up the production of ethylene. Ethylene is the hormone that triggers ripening. Thinning out that foliage also increases air circulation, which reduces the risk of fungal diseases. 

Thin the foliage selectively. Remove any leaves below the first fruit set. These are no longer contributing, but consuming energy. Then cut back or thin out dense foliage around branches with a lot of fruit on them. This lets the sun get through. 

Leave the foliage at the top of the plant alone. Your tomato plants do need some foliage for photosynthesis. Without it, the plant won’t have enough energy to ripen those fruits. 

Root Stress

A careful root nudge promotes healthier fruit growth overall.

We talked about the way that water stress can induce ripening. Root stress is another way to speed tomato ripening. It follows the same notion that when the plant senses that it may not survive long, it will attempt to mature its seeds. 

You can achieve this mild to moderate stress in a couple of ways. You can give the plant a tug from the base to pull on the roots. This will upset them a bit and achieve your goal.

The other method is by driving a spade or fork into the ground a short distance from the stem. Don’t cut in too close to the base. Move out about six inches, and aim to sever some of the feeder roots. 

Pinch New Growth

Cutting new growth encourages the plant to strengthen its fruits.

One of the most reliable ways to speed tomato ripening is to pinch out the new growth. This works only if your days are still warm enough for the plant to produce new growth. As long as it’s relatively warm, the plant will continue to produce new growth and flowers. 

Producing new growth requires energy. Later in the season, that energy would be better spent maturing the existing fruit. We call this method topping, and it’s most useful for indeterminate varieties. 

To top your plants, pinch off the top inch or two of growth, as well as any side shoots that grow from the leaf axils. This prevents the plant from wasting energy on developing new branches. 

Warm It Up

Cover plants at night to trap gentle warming heat.

Artificially warming up your plants is a great way to speed up your tomato ripening in the fall. If you know that the first frost is fast approaching and want to give your tomatoes a little more time on the vine to ripen, this works. 

Tomatoes ripen best when nighttime temperatures are above 55°F (13°C). During the day, 70-85°F (21-29°C) is ideal. You can reflect or absorb and harness heat from the sun and the ground to create ripening conditions around your plants. 

Remember that warmth produces ethylene, which causes ripening. You can cover your plants with row cover or plastic sheeting at night to lock in heat at night. This uses the heat from the ground to raise the temperature. 

During the day, placing dark mulch or stepping stones around the base of the plant also has a warming effect. It absorbs the heat of the sun during the day and bounces it back up into the canopy at night. 

If you’re working with tomato plants in containers, it’s easy to warm them up. Move them against a warm, south-facing wall. The reflected heat that comes off the wall will speed things up.

Harvest Early

Green fruits continue to develop taste once brought inside.

If there’s just not enough time to speed up the ripening of your tomatoes on the vine, it’s fine. They may be slightly less flavorful if you harvest early, but you won’t lose them to frost. They truly don’t need to ripen on the vine; they just need to reach their mature size. 

Once your fruits reach the mature green stage, they contain all the compounds for developing flavor and color. If a frost is impending, pick them and bring them indoors. You can use other methods to ripen them indoors and salvage them from freezing. 

Ripen Indoors

Room temperature trays help fruits slowly deepen in color.

If you’ve decided to harvest them at the mature green stage and ripen them indoors, there are a few methods. Some will speed ripening, while others will be more gradual. The nice thing about this is that you can ripen some of them now, and slowly ripen the rest to keep them fresh longer. 

If you have any fruits at the breaker stage, you’ll want to use the faster method with these. The breaker stage is when they are beginning to show some color, but aren’t ripe yet. These methods will take a few days to a week. 

Ripe bananas and apples produce ethylene gas, which speeds ripening. Place your tomatoes in a paper bag along with a ripe apple or banana, and the gas will speed ripening. This is the fastest method.