8 Reasons Your Tomatoes Aren’t Ripening and How to Ripen Them

If you’re waiting for red tomatoes, but it’s not happening, you have to figure out why your tomatoes aren’t ripening.

Tomatoes are my arch-nemesis. I work hard each year to plant enough tomato plants to provide the right amount of tomatoes I need for canning. Without fail, something goes wrong, and I’m stuck trying to figure out why my tomatoes aren’t ripening.

Is the temperature too cold?

Or is it too hot?

We live in Ohio, so the weather changes as often as I change my clothes.

Is the problem something else entirely?

If you’re like me and wondering why some of your tomatoes aren’t ripening, you have to know the common causes of these problems and what to do if this happens to you.

Related: 12 Gardening Hacks: Growing More Tomatoes This Year

Why Tomatoes Turn Red

There is a whole, scientific reason why tomatoes turn to a red color, but let’s sum it up to make it easier to understand.

Lycopene is a chemical naturally found inside of fruits and vegetables that cause them to develop their color. Lycopene isn’t just found in tomatoes; it is in watermelons, apricots and more. Almost 80% of the lycopene you need in your diet is found in tomato fruit products.

It’s also in all types of tomatoes, whether you grow beefsteak tomatoes or cherry tomatoes!

Believe it or not, your body processes lycopene better when it is heated. Sources such as ketchup and tomato sauce are perfect for getting lycopene into your diet!

Why do you need lycopene? It is valuable in the fight against heart disease, as well as some cancers (colon, pancreas, bladder, ovaries, and breast, to name a few).

When Do Tomatoes Turn Red?

Tomato ripening doesn’t happen overnight; ripening depends on several factors like the type of tomatoes you grow and your growing zone.

However, after the flowers are pollinated on the plants, it takes 6-8 weeks for the flowers to turn into fruits and ripen to a red color.

The month that this happens depends on your growing zone. If you live in a warmer zone, you may start to get red tomatoes as early as June, but in my growing zone, I expect red tomatoes between the end of July and August.

8 Reasons Why Your Tomatoes Aren’t Ripening

1. Longer Time to Maturity

On each seed packet, you will find an average time for maturity for every vegetable you plant. You might be tempted to overlook this date, but I encourage you to pay attention! Certain varieties take less time to mature.

I live in Ohio, and in my growing zones, we have between 140-170 frost-free days. I put this wide range because, in the last few days, we’ve experienced later frosts in the beginning and middle of May.

Ohio weather is wild, y’all!

In general, most tomato varieties require between 90-110 days to mature, so I grow almost all types.

If you have a shorter growing season, you will want to select varieties with a shorter maturity time. It is a good idea also to plug in some longer growing varieties. You can rest assured knowing the shorter varieties will at least yield some fruits for you.

2. Temperatures Are Too Cold

Tomatoes love warm temperatures, which is why you can’t plant them until well after your final frost date for the season.

The optimum temperature for tomatoes is between 68-77 degrees. This is the ideal range for ripening mature green tomatoes. It may happen outside of this range, but it takes longer.

The plants like a consistent temperature range; fluctuating between cooler temperatures and hot temperatures is sure to confuse your plants. However, this fluctuation is normal at the end of the season for gardening.

Unfortunately, our weather in Ohio has been rather unpredictable, and chilly summers are becoming an issue. As I write this, it is the beginning of August, and the high for the day barely touched 80 degrees. That is insane!

Sometimes, you will notice your tomatoes turning pink but never reaching the redness needed to indicate ripeness. They lack flavor, but they will typically ripen if you leave them on your countertops.

One of the best solutions to this problem is harvesting in the green stage and keeping them inside. Tomatoes produce ethylene gas to encourage ripening, so putting them in a paper bag is one way to get them to ripen even if the temperatures outside are too cold.

3. Temperatures are TOO Hot

On the flip side, the temperatures can be too hot for your tomatoes to ripen. High temperatures happened a few years ago, leaving my harvest in ruins. Yes, they love the heat, but they don’t want to roast on the vine with intense heat.

I don’t blame them!

The ideal temperatures for ripening are 70 to 75 degrees F. Once the temperatures go higher than 85 to 90 degrees F, the plant is unable to produce the correct amount of lycopene to create the right pigments. The green ones on your vine will stay green for a long time.

4. You Picked Tomatoes That Aren’t Red

If you grow heirloom plants, there are a lot of varieties that aren’t red. You can buy tomatoes that ripen to pink, yellow, white, orange, purple, and green! They make great additions to the dinner table and farmer’s market stand.

It is easy to forget what varieties you plant; make sure you know your red varieties! You need to mark each variety, so you know what to look for in ripeness. For example, we always grow Brandywine tomatoes. Brandywine ripens to a beautiful pink, but they never turn red. If I forgot, I would let the entire harvest go to waste waiting for red tomatoes to arrive.

5. Stressed or Overgrown Vines

Stress is an energy sucker for humans and tomato plants alike. If your plant only has enough energy to grow new leaves and new flowers, it won’t be able to give any energy into ripening your tomatoes.

Gardeners need to make sure their plants aren’t overly stressed or overgrown, so timely pruning is something that you need to plan. Tomato plants need to be pruned throughout the growing season and six weeks before the first expected frost date in your area.

Pruning tomato plants is important for several reasons.

  • It stops the plant from blossoming further too late in the growing season.
  • Pruning improves airflow, discouraging tomato fungal diseases.
  • It tells your tomato plant to send energy elsewhere.

6. Blossom End Rot

Do your tomatoes have black lesions on them, small or big? If so, you have blossom end rot. It is a disease caused by low calcium in your soil. It is highly suggested that you add natural sources of calcium to your soil during the growing season.

Blossom end rot also forms from uneven watering. If you have frequent downpours of rain, blossom end rot can result.

7. Plants Don’t Receive Enough Sunlight

Another possibility is that you selected a bad location for your tomato plants. Tomatoes love heat and sunlight. The plants need at least seven hours of direct sunlight per day.

You might have picked a great location, but planted them too close together. Tomato plants need at least 18 inches to two feet apart, depending on the variety. Large plants, like the Brandywine, need two feet apart to receive adequate sunlight.

If all else fails, you can take some of your green tomatoes and put them in a cardboard box with a few ripened tomatoes. It should encourage the tomatoes to turn red! I know how it feels to have dozens of plants full of green tomatoes and end up with a pitiful harvest.

8. Too Much Nitrogen in the Soil

Gardeners have good intentions, but at times, that means you may give your plants too much fertilizer. If your tomato plants have too much nitrogen, it leads your plants to produce more leaves rather than focusing their energy on producing new fruits and ripening existing fruits.

This is why you should cut back on fertilizing once your tomatoes set fruit. Fertilizing is essential, but you should ideally only fertilize tomato plants two or three times in the growing season.

Related: 11 Natural Nitrogen Sources All Gardeners Need to Know

7 Tricks to Try if Your Tomatoes Aren’t Ripening

Once you figure out what the problem is, you can try some different tricks to help your tomatoes ripen on the vine. Now, nothing totally fixes the problem – we can’t control the weather, but when fall is approaching, give these ideas a try.

1. Cut Off The New Growth

As your growing season comes to an end, your plant no longer needs to focus energy on growing new leaves. So, try topping the plant and removing new growth to force the plant to send more of its energy into ripening tomatoes faster.

Plants only have a set amount of energy to give, so they prioritize where to send their energy based on the plant’s needs. If your plant has new branches, it sends the attention towards this area for larger growth.

Unfortunately, your plants have no idea that you have a time crunch, and that tomatoes not turning red is a big deal. So, trim off new stems and leaves, forcing the plant to send its energy towards ripening fruits.

2. Trim Off the Flowers

When fall is looming, any new floors won’t have time to turn into a tomato and ripen before cold weather strikes. It takes an average of 6-8 weeks for this process to take place.

So, it’s a sure bet that those flowers are simply an energy sucker. Pick those off and tell the plant to focus its energy on ripening the tomatoes it already has on the plant.

3. Remove Suckers

If you haven’t focused on removing suckers throughout the growing season, now is the time. Suckers are smaller stems that grow between a branch and a leaf joint. Removing suckers is a great idea because, as their name suggests, they suck energy from your plant.

Despite looking like a branch, suckers will never produce fruits! Pinch off the suckers to stop the removal of that energy.

Related: How to Prune Tomato Plants: 7 Steps for Success

4. Take Off Tiny Tomatoes

While the tiny tomatoes on your plants are adorable, they won’t have time to mature before the frost. Removing tomatoes a few weeks before the first frost will help your plant send energy towards ripening.

Don’t forget; green tomatoes are edible, so don’t toss them out! You can find all kinds of things to do with green tomatoes.

5. Prune Some Leaves

You don’t want to cut off all the leaves of your plant because leaves pull in the sunlight and lead to food production. Plants die if they lose all of their leaves.

Removing some leaves is recommended if you have a huge tomato plant with healthy leaves but the tomatoes aren’t ripening. Trimming off some of the vigorous growth stops the energy-sucking.

6. Keep The Plants Dry

In the fall, late blight is a real issue; it destroys the fruits on your plants if it takes hold. One of the best preventative measures against late blight is to prevent soil from touching the plants. You should also try to tie the long branches to cages or stakes to stop the branches from touching the ground.

7. Protect Plants from Cold or Hot Weather

You know that weather plays a huge part in tomato ripening. However, if you can keep your plants between the optimal temperatures (between 68-77 degrees F), you have a better chance of seeing color changes in your tomatoes.

When temperatures get too high, protect the plants from heat, using things such as shade cloth, extra mulch, and additional watering.

When temperatures are below the necessary range, use protective fabric or bring container-grown tomatoes indoors to be safe. Row covers keep plants warm when the temperatures dip too low. If your plants are still small enough, you may be able to use garden cloches!

How to Ripen Tomatoes Indoors

Sometimes, when your tomatoes aren’t ripening, it’s time to admit defeat and start ripening tomatoes indoors. The flavor is different when you have to ripen tomatoes indoors; vine-ripened tomatoes are THE best.

However, ending with tons of wasted tomatoes is even worse, so it’s worth the shot. There are a few ways to attempt this, so let’s go through your options.

Bring Container-Grown Tomatoes Inside

If you have tomatoes in containers, the easiest choice is to bring the entire plant inside your house where its warmer. This is one great reason to grow tomatoes in containers (at least a few!)

Uproot and Hang Upside Down

If you have space in your basement or garage, another option is to dig up and uproot your entire tomato plant, full of green tomatoes. Then, hang the tomato plants upside down from the rafters until the fruits are ripened.

The roots have to be attached for this to be successful, and you have to make sure the area you select is well-lit but not in direct sunlight. Keep them in an area that has a consistent, room temperature range between 50-70°F.

Leave on the Counters to Ripen

Another option is to bring the unripe tomatoes inside and put them on your kitchen counter or window sill to ripen. If you leave them for long enough, they’ll produce ethylene and cause the fruits to ripen.

Use a Brown Paper Bag

If you’re feeling particularly impatient, the best thing to do is put the unripened tomatoes in a paper bag with an apple or a ripe banana. Adding the fruits will help speed up the ripening process because they also give off ethylene gas.

Ripen Your Tomatoes

If you’re tomatoes aren’t ripening, don’t stress. Try to identify the reasons why your tomatoes aren’t turning red, and then use some tricks to ripen the tomatoes so your family can enjoy them.

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