Why Are My Tomatoes Not Ripening? Reasons & Easy Solutions

Quick Answer: Why Are My Tomatoes Not Ripening

Your tomatoes may not ripen because the weather is extremely cold or the plant has too much leaf mass which prevents it from concentrating its energy to ripening. Green collar disease can also be a contributing factor.

In this post, we’ll see the reasons why your tomatoes are staying “ever-green”, refusing to ripen, and proffer some working solutions.

Keep reading to find out why your tomatoes are not ripening and what to do.

When is the normal ripe time for tomato fruits?

During the ripening process, the red varieties usually change from an initial green to a juicy red. The red color is supposed to protect against extreme sunlight, signal full ripeness, and at the same time attract animals.

But sometimes the fruits just don’t want to turn red. This can have different causes but can usually be remedied with a few little tricks.

The tomato plant, botanically Solanum Lycopersicum, will only be planted outdoors in late spring or early summer, around early February to mid-May.

It is allowed to move into the greenhouse a few weeks earlier. Then it takes about two months for the seedling to bear the first red berries.

In the open field, the harvest begins towards the end of July and ideally lasts into autumn because new fruits are constantly growing. Once the tomatoes have reached the size typical of the variety, they begin to turn red.

Within a few days, the color changes from green to green-yellow and orange to red. Of course, some varieties show themselves in different colors when ripe, such as yellow.

Small delays are normal

If two months after planting, there are still no red tomatoes on the otherwise healthy plant, this is not necessarily a cause for concern.

Summers, in some parts of the world, are not exactly known for consistent weather. Temperatures can often fluctuate considerably during the tomato plants’ vegetation period from mid-May to around the end of September.

If there are many more rainy days, it is not surprising that the normal development takes a long time. Then the harvest time can start up to three weeks later.

The conditions also become more and more unfavourable towards autumn. In this situation, not all tomato fruits will ripen.

What Causes Tomatoes to Stop Ripening?

It takes about eight to nine weeks from the planting of the seedling to the fully ripe fruit. The red colour is the last development step of the tomato before harvest and usually only takes a few days.

For various reasons, however, this last step can be delayed or even not taken at all.

1. Temperatures are too low

Tomato plants are supposed to be very warm. Make sure they are in a sunny location and are protected from rain. Do not plant outdoors before the Ice Saints.

Frost is deadly for plants and fruits. In greenhouse crops, it can get very hot very quickly. Temperatures that are too cold slow down the development of plants and fruits.

Otherwise, even if there is fruit formation, the red color only occurs slowly or does not appear. Then your fruits will stay green and unripe.

2. Too much leaf mass

Another reason for a delay in the ripening of tomatoes can be too much leaf mass. Tomato plants are constantly forming new shoots and leaves.

The more shoots and leaves they form, the less energy they have to develop and ripen fruits. You can remedy this by regularly maxing out the plants, i.e., pruning superfluous shoots.

How to troubleshoot - The bottom leaves of tomato plants should generally be removed to counteract the dreaded late blight and brown rot.

Below is a video tutorial that shows how to prune tomato leaves:

3. Green Collar Disease

The ripening process is interrupted when the so-called green-collar disease sets in, so the fruits will not turn completely red.

At the base of the stem, there remains a circular, green stripe that is very hard, which also continues under the skin. The green is clearly distinguished from the red.

The cause can be too much sunlight, temperatures above 30 ° C, too intensive watering, as well as a lack of potassium or excess nitrogen.

This disease can be avoided by shading the plants slightly in strong sunlight and heat.

Stop fertilizing with too much nitrogen and ensure that there is an adequate supply of potassium and magnesium. A soil analysis can also be useful.

How to troubleshoot - Some varieties are particularly susceptible to this disease, such as Harzfeuer tomatoes, which you should consider when choosing a variety. Small-fruited, panicle, and bush tomato varieties are relatively rarely affected.

4. Wrong location

One of the most common causes of the tomato not turning ripe and red is the incorrect location of the tomato plants.

The fruits like it sunny and warm. However, in partially shaded locations, the plants may wither, or at least, refuse to ripen.

Did you know that tomatoes need at least 8 hours of sun a day?

How to troubleshoot - If the valuable solar radiation is missing, a plant lamp, such as the 4FT LED Grow Light, in a greenhouse can help. These full-spectrum lamps equipped with LEDs help the fruits ripen.

5. Wrong soil

Tomato is a demanding crop and only thrives in nutrient-rich, fresh soils. In nutrient-poor soil, the tomato stays green for months and does not ripen.

However, overfertilization and the use of the wrong fertilizer can also slow down the ripening process or bring it to a standstill.

How to troubleshoot - Optimal soil for tomato plants has the following properties: 

1. Good drainage, no waterlogging
2. Rich in nutrients
3. Moderate clay content
4. Neither too damp nor too dry

Note: Again, an oversupply of nitrogen-rich fertilizers can delay the ripening process. Also, a lack of potassium or magnesium slows down the ripening process.

Too Cold Weather

One of the most common causes of the fruit staying green for too long is, in the worst case, a cold, rainy summer. If the location is wrong, the tomatoes hardly ripen.

Another requirement for the optimal location for tomato plants is adequate protection from wind and rain.

In exposed places, the fruits may not turn red and ripe despite long exposure to the sun. Therefore, the best locations for tomato plants are a greenhouse or the south side of the house.

How to troubleshoot - A ripening hood or plastic film can help to ensure that the fruits turn red and ripe outdoors. Under the tomato cover, the plants are not only protected from rain and wind but are also in a warm, favorable environment. The tomato hood is especially recommended in bad weather.

How Do I Get My Tomatoes to Turn Red?

To promote the ripening process in the greenhouse, you can hang bananas or apples next to the plants. These give off the ripening ethylene gas, which can accelerate the ripening process of tomatoes. Tomato plants also produce this gas themselves, but they have to use a lot of energy, for which they need a lot of heat and water.

To make the fruits ripe faster, try out the following tips:

Reduce the watering amount

The deprivation of water can induce the plants to promote the ripening of the fruit. However, you shouldn’t start doing this before autumn.

As long as the plant is growing and producing fruits, it is dependent on a regular and abundant supply of water.

In autumn, when the fruits have reached their final size and do not want to turn red, the intervals between the waterings are extended, and watering is only done about every three days.

The reduced water supply is intended to signal to the plant that its growth is complete. As a result, they put all their energy into the ripening process of the fruit.

Reduce light

Tomatoes don’t necessarily need direct sunlight to ripen up. All they need is warmth. The situation with the withdrawal of light is similar to that of dehydration.

As long as the tomato plant is growing and producing fruits and seeds, it cannot do without sufficient light either.

As soon as the fruits are fully grown, they get by with significantly less light because the light intensity hardly plays a role in the red color of the fruits.

They can turn red even in complete darkness. To speed things up, you can put tomatoes in the pot or tub in a shady place and cover the plants in the bed, probably with a fleece flower.

If all else fails – pick green tomatoes and let them ripen

It often happens that the tomato season in the garden is over, but many fruits are still green.

Before the frost kills them, they should be harvested and allowed to ripen indoors. It is best to harvest them as soon as the temperatures drop permanently below 10 ° C.

Always harvest unripe tomatoes with the stem. Green tomatoes for subsequent ripening should not have any damaged areas. Cracks are entry points for germs.

Also, mold often forms on the cracks, and the fruits may spoil. Check fruits for brown spots, risk of brown rot.

The fruits can be placed in fruit boxes and stored in a suitable place.

The tomatoes should not lie on top of each other, if possible, and should be regularly checked for damage or rot, and the corresponding fruits should be sorted out.

If you want, you can put an apple in the box and use the ripening gas that escapes for the ripening process.

The fruits can be placed in fruit boxes and stored in a suitable place. You can put a banana or an apple in the container because they emit a ripening gas.

But in our opinion, it doesn’t need that at all. Check it after every few days, and you will see that some tomatoes still turn red even without a bush, water, or light.

The remaining green tomatoes can still be processed into a chutney, for example (boil down with sugar and vinegar).

Tips and Advice for Great Ripened Tomatoes

Here are some tips!

For the best taste, eat your tomatoes as soon as they have ripened. They will gradually lose their taste after a week in the refrigerator.

You should never eat unripe, green tomatoes. They are too acidic and can be poisonous except for special green varieties. The solanine content in unripe fruits is so high that it is harmful to health.

If fruits remain unripe in the greenhouse for a long time, ripe bananas or apples should be placed near them. The two types of fruit are known to release large amounts of the gaseous phytohormone ethylene or ethene during the ripening process. The plant hormone promotes the ripening of the fruits in the area.

If the weather is permanently unfavourable, tomato tubs and pots should be brought from the balcony or terrace to a winter garden or indoors. The ripening process gets going in the warm air and on a sunny window sill or under the light of a plant lamp.

To harvest a juicy, bright red tomato with a full-bodied taste, the tomato plants should be stripped regularly. Pruning means removing shoots that grow in the leaf axes. Ideally, the side shoots should be removed as soon as they measure a few centimeters. In this case, the shoots can be removed with your fingers without secateurs.

It would be a mistake to remove too many shoots. A tomato plant needs leaves for photosynthesis and healthy growth. When pricking out, caution and a good sense of proportion are required.

If the tips still don't help or if the first frost is already approaching, you can still harvest all of the fully grown but green tomatoes in good time. Then place these tomatoes in a cardboard box, dark paper bag, or individually wrap in a newspaper for a few days. Next, store the tomatoes at least 18 degrees in a non-sunny place (e.g., kitchen cupboard).

FAQs

Do tomatoes need the sun to ripen?

Tomatoes don’t necessarily need direct sunlight to ripen up. All they need is warmth. Fruits that are exposed to too much direct sunlight will heat up to a level that inhibits pigment synthesis. Direct sunlight can sunscald the fruit.

Can the tomatoes tolerate a change of location?

Yes, if the outdoor tomatoes are not red and ripe, you can move the outdoor tomatoes. Carefully dig up the plant so as not to damage the roots. Water the repotted plant abundantly. Tomato plants in pots and containers can easily handle a change of location.

Can I eat unripe green tomatoes?

No, that would not be a good idea. The side effects are not serious, but there are side effects nevertheless. Unripe, green tomatoes contain around 30 milligrams of natural toxin solanine per 100 grams of weight. After eating only two green tomatoes, symptoms such as headache, nausea, and cramps may become noticeable. For comparison: red and ripe tomatoes contain only 1 milligram of solanine per 100 grams of pulp. 400 milligrams of this natural poison can even be fatal.

Can tomatoes ripen after harvesting?

Yes, the tomatoes will ripen after they’re harvested in a green state. Wrap the fruit in blank paper or a piece of cloth, place a ripe banana or apple nearby, and wait a few days. Most of the fruits will turn red and ripe. Alternatively, cut the plant near the roots and hang it up at home. A tomato only becomes red and ripe in a warm, dry place.

Are there varieties that are ripe but stay green?

Yes, “Green Zebra” is the best known of these types of tomatoes. Aunty Ruby’s German Green is another.
When the fruit ripens, hardly any color is formed; the tomato stays green but tastes full-bodied.
You don’t have to worry about the solanine content – this dangerous active ingredient is broken down when “Green Zebra” or any other ripens in the same way as when classic red fruits are ripened.

Which tomato varieties are less susceptible to green collar disease?

Cherry, cocktail, and vine tomatoes show green stems less often. Bush tomatoes are also largely resistant to this. Varieties with light-coloured tomatoes are less susceptible than varieties with darker fruits. However, the popular “Harzfeuer” variety is an exception because it is prone to this disease.

Summary

We hope you can now take care of your tomato plants so they can ripen naturally and at the appropriate time.

If they don’t, you can take them through any of the suggested post-harvest ripening processes.

If you have further questions, kindly ask. And if you enjoyed the article, please share.

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