Why Tomatoes Take So Long to Redden

Ethylene — The Conductor of Ripening

The tomato is a so-called climacteric fruit. This means that at a certain point, its production of ethylene—a gaseous plant hormone—sharply increases, triggering a cascade of changes (Mattoo & Vickery, 1977; Mattoo et al., 2017). Under the influence of ethylene, dozens of genes are activated: the breakdown of chlorophyll (the pigment that makes the fruit green) begins, and simultaneously, carotenoids—lycopene and β-carotene—are synthesized, coloring the fruit red or orange (Gavrish, 2005). Ethylene also causes cell walls to soften, starch to turn into sugars, and aromatic compounds to form.

Therefore, the first and main question when ripening is delayed is: why is ethylene not being produced or not working?

Temperature: Too Hot and the Process Stops

The production of ethylene and the synthesis of lycopene are highly dependent on temperature. The optimal range for tomato ripening is 20–25°C during the day and 16–18°C at night (Gavrish, 2005). At temperatures above 30°C, lycopene synthesis is practically blocked, and at 35–36°C, it completely stops (Mattoo et al., 2017). The fruit may continue to grow but remain yellow-orange or even greenish because carotenes break down faster than they accumulate.

On the other hand, at temperatures below 14–15°C, the ripening process slows down significantly: ethylene is produced, but very slowly, and fruits can hang for weeks at the "mature green" stage.

Light — Not as Crucial as Often Thought

Unlike many other plant processes, tomato fruit ripening does not require direct sunlight. Lycopene is synthesized in the dark, and fruits can turn red even inside a dense canopy or under cover. However, light is important for warming the fruit and for photosynthesis in the leaves, which supply sugars. If a fruit is heavily shaded, it receives fewer assimilates, and ripening may be delayed due to an overall lack of nutrition (Mattoo et al., 2017).

Nutrition: What the Fruit Needs to Turn Red

The key element for ripening is potassium. It is potassium that is involved in transporting sugars from leaves to fruits and in the synthesis of lycopene (Gavrish, 2005). With potassium deficiency, fruits ripen unevenly, often with green shoulders near the stalk.

Nitrogen in excess acts oppositely: it stimulates vegetative growth (leaves and shoots) at the expense of generative development. With nitrogen overfeeding, fruits can stay green for a long time, and plants become "lush" — with dark green large leaves and weak flowering (Gavrish, 2005).

Phosphorus (for energy metabolism) and magnesium (for photosynthesis) are also important, but their deficiency is less often a direct cause of delayed reddening.

Brief summary of Chapter 1:

• Ripening is triggered by ethylene.
• Ethylene and the synthesis of the red pigment (lycopene) are sensitive to temperature: optimal is 20–25°C, above 30°C — blocked, below 15°C — significantly slowed down.
• Light is not directly needed for reddening but is important for the overall nutrition of the fruit.
• Potassium accelerates ripening, excess nitrogen delays it.

In the next chapter, we will analyze the main reasons for delayed ripening and learn how to diagnose them by external signs.

Diagnostic Table: Why Tomatoes Are Not Turning Red

Explanations for Key Points

Why heat blocks reddening. At temperatures above 30°C, the activity of the enzyme lycopene synthase, which converts the colorless precursor into red lycopene, is suppressed (Mattoo et al., 2017). The fruit may even start to turn yellow (due to the accumulation of β-carotene) but not red. This is not a disease but a physiological failure.

Why cold slows down the process. At low temperatures, not only lycopene synthesis slows down but also ethylene production. The root system absorbs potassium and phosphorus less effectively, which exacerbates the situation (Gavrish, 2005). The critical threshold for tomatoes is a night temperature below 10°C: growth stops completely.

How to distinguish potassium deficiency from a genetic trait. Potassium starvation has a characteristic sign — "green shoulders" (the stalk and adjacent area remain green or yellow, even when the rest of the fruit has turned red). This is a direct consequence of disrupted sugar and pigment transport. In varieties with a genetic predisposition to "green shoulders" (e.g., some older varieties), this effect appears even with good nutrition, but to a lesser extent.

Excess nitrogen — the most common mistake. Gardeners often overfeed tomatoes with manure or nitrogen fertilizers in the first half of summer. This leads to a powerful leaf apparatus, but flowering and fruit set are delayed. Nitrogen stimulates the growth of vegetative organs, and switching to ripening requires a signal (ethylene), which is suppressed by excess nitrogen (Gavrish, 2005). If you notice "lush" growth, immediately stop watering for a week and apply phosphorus-potassium fertilizer.

Crop overload — a hidden threat. Each fruit is a "pump" that draws sugars and water. If there are too many clusters, the plant cannot provide all fruits with nutrition, and ripening stretches over weeks. This is especially noticeable in indeterminate varieties in greenhouses, where clusters form continuously. Removing excess ovaries is one of the fastest ways to accelerate the reddening of the remaining fruits (Mattoo et al., 2017).

Shading and leaves. Direct sunlight is not required for lycopene synthesis, but lighting is important for warming the fruit and for the photosynthesis of nearby leaves that feed the cluster. If the cluster is covered by three layers of leaves, it will starve. Removing 2–3 old lower leaves above each cluster improves light and air access.

Variety characteristics — not a problem. Different varieties have different growing seasons: from 85 days (ultra-early, e.g., 'Betta', 'Gavrosh') to 140 days or more (late large-fruited). If you planted 'Russian Size', don't expect reddening in early July — that's normal. Always check the variety's characteristics when buying seeds (Gavrish, 2005).

In the next chapter, we will analyze specific techniques on how to accelerate ripening in a greenhouse using ventilation, thinning, and temperature control.

1. Ventilation: Dry Air is the Key to Fast Ripening

Air humidity above 70–75% not only provokes fungal diseases (late blight, gray mold, cladosporiosis) but also inhibits ripening. At high humidity, pollen sticks together, fruit set worsens, and ethylene release slows down.

What to do:

• Open all vents and doors in the greenhouse daily, even in cloudy weather, but avoid drafts that can damage flowers.
• On sunny days, start ventilating in the morning as soon as the temperature inside exceeds 22–23°C.
• In hot weather, leave ventilation openings open at night if the night temperature does not drop below 14–15°C.
• Optimal humidity for tomatoes during ripening is 60–70% (Gavrish, 2005). If humidity is higher, increase ventilation and reduce watering.

Why it works: Reducing humidity improves evaporation from leaves, enhances root pressure, and transports nutrients to fruits. Additionally, dry air promotes better pollination and fruit set on upper clusters.

2. Reducing Soil Moisture: Mild Stress Accelerates Reddening

Excessive watering during the ripening period is a common mistake. When the soil is constantly saturated with moisture, the plant spends energy on vegetative growth, and ripening is delayed.

What to do:

• 2–3 weeks before expected mass ripening, reduce watering to once every 5–7 days (depending on weather).
• Water only at the root with warm water (20–25°C), avoiding water on leaves and fruits.
• Rely on soil condition: the top layer should dry to a depth of 3–5 cm between waterings.
• On heavy clay soils, water less often but more abundantly to soak the root zone.

Why it works: Mild water stress stimulates ethylene production and accelerates the transition of fruits to ripening. However, severe drying out should not be allowed — it leads to fruit cracking and dropping of ovaries (Mattoo et al., 2017).

3. Thinning Clusters: Quality Over Quantity

In a greenhouse, especially for indeterminate varieties, a plant can form up to 15–20 clusters or more. If their number is not limited, all fruits will be smaller and ripen with a significant delay.

What to do:

• For determinate varieties, leave 5–6 clusters; for indeterminate ones, 8–10 (Gavrish, 2005).
• On each cluster, leave 4–6 of the largest and most even ovaries, remove the rest as soon as they become visible (at the "pea" stage).
• Regularly (once every 10–14 days) inspect plants and remove all newly appearing side shoots (suckers) so that all the plant's energy goes into filling the already set fruits.

Why it works: Each fruit is a consumer of assimilates. The fewer fruits competing for nutrition, the faster they gain mass and trigger the ripening program. Thinning also improves lighting and ventilation for the remaining clusters.

4. Leaf Removal: Light and Air for Each Cluster

Old, yellowed, and lower leaves not only shade the fruits but also create hotspots for fungal infections. Their timely removal is one of the most effective techniques for accelerating ripening.

What to do:

• Remove all leaves below the first ripening cluster. This is usually done gradually, 1–2 leaves per week, to avoid weakening the plant abruptly.
• Remove leaves that directly shade the clusters, especially those growing over the fruits.
• Leave at least 5–6 full leaves on each shoot above the top cluster — they are needed for photosynthesis and feeding the last fruits.
• Do all removals in the first half of the day, in sunny weather, so that wounds dry quickly.

Why it works: Leaves that no longer actively participate in photosynthesis (old, diseased, heavily shaded) become "parasites" — they consume nutrition but give almost nothing to the fruits. Removing them redirects assimilate flows directly to the clusters. In addition, air circulation improves, humidity decreases, and disease risk is reduced.

5. Temperature Control: Keeping Fruits in the "Comfort Zone"

In a greenhouse, temperatures can rise above 35°C even in temperate zones if ventilation and shading are not monitored. Conversely, on cool nights, temperatures can drop below 12–14°C, which inhibits ripening.

What to do in heat:

• Whitewash glass roofs with a weak chalk solution or use special shading nets (20–30% shade).
• On the hottest days (above 30°C), use fine misting outside the greenhouse or wet the pathways — this lowers the temperature by 2–3°C.
• Ensure intensive ventilation by opening all possible openings.
• Water in the morning so that the soil is moist but not wet by noon.

What to do in cold:

• If nights are cold (below 12°C), use additional plant cover with non-woven material (lutrasil, agrotex) directly over the trellis.
• In unheated greenhouses, use heat guns or oil radiators on the most critical nights (especially in late August — early September).
• Reduce ventilation in the evening to retain accumulated daytime heat.

Optimal values:

• Daytime in sunny weather: 22–25°C (for ripening)
• Daytime in cloudy weather: 20–22°C
• Nighttime: 16–18°C (not below 14°C)

Why it works: Temperatures above 30°C block lycopene synthesis, while below 14°C sharply slow ethylene production. Keeping fruits in the "golden range" of 20–25°C guarantees maximum reddening speed (Mattoo et al., 2017; Gavrish, 2005).

Additional Technique: Ethylene Stimulation

A ripe fruit releases ethylene, which accelerates the ripening of neighbors. Place 2–3 fully red tomatoes next to green clusters (you can put them in a plastic bag with several green fruits for a day, but do not completely block air access). This "infects" neighboring fruits with ethylene and triggers a chain reaction. However, the method works only at normal temperatures (not below 18°C).

Brief summary for greenhouses:

• Regular ventilation reduces humidity and temperature.
• Moderate water stress stimulates ripening.
• Removing excess clusters and ovaries redirects nutrition to remaining fruits.
• Removing old leaves opens access to light and air for the clusters.
• Maintaining a temperature of 22–25°C during the day and 16–18°C at night is a key condition.

In the next chapter — how to accelerate ripening in open ground, where there are fewer control options but some effective techniques exist.

1. Temporary Covers: Protection from Cold and Excessive Moisture

In temperate and northern regions, the main enemies of ripening are cold nights (below 12–14°C) and prolonged rains. Covers help retain heat and prevent root hypothermia.

What to do:

• Use arches with non-woven cover material (spunbond, agril, lutrasil with a density of 30–60 g/m²) — they let through light, air, and moisture but create a "microclimate" 2–4°C warmer than outside.
• In case of frost or sudden cold snaps, cover plants at night and leave cover until morning when the temperature rises above 15°C.
• During rainy periods, use film tunnels with end ventilation — they protect against soil waterlogging and reduce the risk of late blight.
• For individual plants, you can use cut plastic bottles or agro-fabric caps, removed during the day and put on at night.

Why it works: Cover raises air and soil temperature by 2–3°C, bringing conditions closer to optimal for lycopene synthesis and ethylene release. It also prevents moisture from getting on leaves and fruits, reducing the risk of fungal diseases that slow ripening in weakened plants (Gavrish, 2005; Mattoo et al., 2017).

2. Protection from Rain and Excess Moisture

Soil waterlogging in open ground is one of the main causes of delayed ripening: roots suffocate, nutrition is blocked, and fruits remain green.

What to do:

• During prolonged rains, make film "umbrellas" or canopies over the beds from transparent film stretched over a frame (so water drains into the rows).
• Organize drainage ditches between rows to drain excess water.
• If the bed is flat, make small earth mounds around the plants to prevent water from stagnating at the root collar.
• After rain, gently loosen the soil to a depth of 3–5 cm to restore air exchange in the root zone.

Why it works: Waterlogged soil is poor in oxygen; roots stop absorbing potassium and phosphorus, and the plant spends energy adapting to stress rather than ripening. Drainage and loosening restore normal root nutrition, which immediately affects the speed of reddening (Gavrish, 2005).

3. Crop Thinning and Removing Excess Ovaries

In open ground, plants often carry more fruits than they can "feed" before cold weather arrives. Extra clusters divert resources and delay the ripening of all fruits.

What to do:

• For determinate varieties, leave 4–5 of the strongest clusters, remove the rest at the ovary stage (as soon as fruits reach the size of a pea).
• For indeterminate varieties in open ground, it makes sense to leave no more than 6–7 clusters — anything that sets after August is unlikely to ripen in time.
• In each cluster, leave 4–5 large fruits, pinch off the rest (smallest, deformed).
• Pinch the growing point of the main stem 30–40 days before expected frosts, leaving 2–3 leaves above the top cluster — this stops the formation of new inflorescences and directs nutrition to existing fruits.

Why it works: The fewer fruits competing for assimilates, the faster they reach physiological maturity and trigger the ethylene signal. Limiting the number of clusters is the fastest way to accelerate the reddening of the remaining ones (Mattoo et al., 2017; Gavrish, 2005).

4. Potassium and Phosphorus Fertilizing (No Nitrogen)

In open ground, it is easier to lose nutrient balance due to fertilizer leaching by rains. Potassium is the key element for ripening, and nitrogen should be excluded during this period.

What to do:

• Apply foliar feeding with monopotassium phosphate (10–15 g per 10 L of water) on the leaves — this quickly delivers potassium and phosphorus directly to the fruits.
• Root feeding: potassium sulfate (15–20 g/m²) or wood ash (1 glass per bucket of water, steep for a day, and water 1 L under each bush).
• Completely exclude nitrogen fertilizers (nitrate, urea, manure infusion) from the moment the first fruits begin to redden.

Why it works: Potassium activates the enzymes of lycopene synthesis and sugar transport, while phosphorus improves cell energetics. Excess nitrogen, on the contrary, stimulates leaf growth at the expense of ripening. A "potassium push" in late summer is a standard agricultural practice to accelerate harvest yield (Gavrish, 2005; deficiency sign table, pp. 145–146).

5. Pinching Tops and Removing Suckers

In open ground, especially in regions with short summers, stopping vegetative growth is critical for fruits to ripen before cold weather.

What to do:

• Starting from late July — early August (depending on the region), regularly remove all suckers (side shoots) longer than 2–3 cm so that the plant does not waste energy on excess greenery.
• In the first decade of August, pinch the top of the main stem on indeterminate varieties, leaving 2 leaves above the last cluster. For determinate varieties, pinching is usually not required, but you can pinch the growing point on strong side shoots.
• Remove all flowering clusters that clearly will not have time to set large fruits before September.

Why it works: Pinching redirects photoassimilates from growing points to fruits, accelerating their filling and reddening. This is especially relevant in August when daylight decreases and nights become cooler (Gavrish, 2005).

6. Harvesting Brown Fruits for Ripening — As a Way to Accelerate Ripening of Remaining Ones

This technique works especially effectively in open ground because green fruits left on the bush may not have time to turn red before frost.

What to do:

• Start harvesting fruits at the brown ripeness stage (when they begin to turn pink but are still firm) and place them in boxes in a warm room for ripening.
• After harvesting the first brown fruits, the remaining green fruits on the bush begin to redden faster because competition for nutrition decreases, and the plant receives a signal "it's time to finish the cycle."

Why it works: Removing brown fruits from the plant reduces the load on the root system and stimulates the ripening of the remaining ones, as the plant "understands" that vegetation is ending. In addition, brown fruits release ethylene during ripening, which can be used to accelerate the ripening of green fruits indoors (more details in Chapter 6).

Additional Technique: Treatment with Stimulants

There are preparations based on gibberellins and other growth regulators on the market that promise accelerated ripening. However, for amateur gardeners, we recommend using them with caution: in open ground, they can have unpredictable effects due to weather fluctuations. A safer method is spraying plants with a weak solution of succinic acid (0.002–0.005%) or preparations based on chitosan, which gently stimulate protective reactions and slightly accelerate metabolism. But the main thing — do not replace basic agricultural practices with them (thinning, covering, potassium fertilizing).

Brief summary for open ground:

• Covers protect against cold and waterlogging, creating a microclimate.
• Draining excess water and loosening restore root respiration.
• Thinning clusters and fruits is the fastest way to accelerate ripening of the remaining ones.
• Potassium fertilizing and excluding nitrogen are the key nutritional decision.
• Pinching tops and removing suckers in August stop growth and direct nutrition to fruits.
• Harvesting brown fruits unloads the bush and triggers the ripening of the rest.

In the next chapter, we will analyze in detail whether to remove leaves and how to do it correctly without harming the plants.

Why Remove Tomato Leaves at All?

This procedure has three important tasks, all directly related to accelerating ripening:

1. Redirecting nutrition. Old, yellowed, or diseased leaves no longer produce enough sugars but continue to consume resources for their maintenance. By removing them, we direct assimilates to the fruits (Gavrish, 2005).

2. Improving lighting. When a fruit cluster is shaded by 3–4 layers of leaves, the fruits receive less heat (meaning lycopene synthesis slows down) and fewer assimilates from nearby leaves. Illuminated fruits redden faster even in open ground.

3. Reducing humidity and preventing diseases. In a dense canopy, air stagnates, humidity rises, and ideal conditions are created for late blight, gray mold, and cladosporiosis. Removing lower leaves improves ventilation, especially in greenhouses and during the rainy season (Mattoo et al., 2017).

Which Leaves to Remove — and Which to Keep?

There are clear criteria — a leaf is removed if it falls under at least one of the following points:

Important rule: Never remove all leaves at once — this is severe stress for the plant. Losing more than 30% of the leaf apparatus in one day leads to growth arrest and delayed ripening, as the roots are left without a "pump" — transpiration (Gavrish, 2005).

When and How to Properly Remove Leaves

Timing:

• Start removing lower leaves 2–3 weeks after planting seedlings in the ground, when plants have established and begun to grow.
• During the active growth of clusters (from ovary to the start of reddening), carry out removal regularly — once every 7–10 days, 1–2 leaves per plant at a time.
• Stop mass leaf removal when mass reddening of fruits begins — now the plant needs all its leaf mass for final filling.

Technique:

• Remove leaves only in the first half of the day, in sunny weather, so that cuts dry quickly and do not become entry points for infection.
• Use sharp, clean pruners or a knife. Do not break leaves off by hand — ragged wounds take longer to heal and are more often affected by rot.
• Cut the leaf at the very base, leaving a stump 1–2 cm long. Do not cut flush with the stem — this can damage the axillary bud and slow growth.
• If you remove a leaf above a cluster, leave a petiole 1–2 cm long to avoid damaging the fruit stalk.

After removal:

• If humidity is high in the greenhouse, immediately ventilate so that sap droplets on the cuts dry quickly.
• In open ground, postpone removal to a dry day after rain.
• Remove cut leaves immediately from the bed and destroy them (compost separately, not near plantings).

Why You Can't Remove All Leaves "To the Ground"

Sometimes gardeners get carried away and cut off all leaves, leaving only clusters with fruits. This is a serious mistake:

• Leaves are the "factory" of sugars and amino acids that go into fruits. Without them, fruits become smaller, lose flavor, and do not accumulate the sugar content characteristic of the variety.
• Roots feed on photosynthesis products. If there are too few leaves, the root system weakens, and the plant begins to starve, even if all elements are present in the soil (Gavrish, 2005).
• A sharp loss of foliage triggers a stress reaction that may, on the contrary, delay ripening: the plant switches to an "emergency" mode rather than completing its cycle.

Optimum minimum: at least 5–6 full (large, dark green) leaves should remain on each plant above the top cluster. For indeterminate varieties in a greenhouse, you can leave 8–10 leaves along the entire height of the trellis, but it is important that they are evenly distributed along the stem.

Special Cases: Leaf Removal During Ripening

If you practice harvesting brown fruits for ripening (see Chapter 6), removing lower leaves becomes even more relevant: the freed space improves air circulation and accelerates the reddening of remaining fruits on the bush. But even in this case, leave at least a minimum of leaves above the top cluster — they will feed the fruits until the very frosts.

Brief rules for leaf removal (cheat sheet):

Brief summary: Leaves should be removed, but moderately and according to rules. Remove only those that no longer work for the harvest, and do it gradually so that the plant does not experience shock. Leave at least 5–6 full leaves for feeding fruits and roots. Proper leaf removal is one of the safest and most effective ways to accelerate ripening, if combined with other techniques (thinning, potassium, temperature).

In the next chapter, we will answer an important practical question: when to harvest brown fruits and how to properly ripen them to preserve flavor and not spoil the harvest.

What is "Brown Ripeness" and How to Identify It

Brown (or blush/breaker) ripeness is a transitional stage between mature-green and full red. At this point, the fruit has reached its maximum size, seeds have formed, but coloring has only just begun to change.

Signs of brown ripeness:

• The fruit's color becomes light green with a pinkish or brownish tint (for red-fruited varieties) or begins to turn yellow (for yellow-fruited ones).
• When cut, the flesh around the seed chambers becomes pink or reddish, while the central part is still green.
• The fruit is firm, but when pressed, it is no longer "rock hard" — you can feel a slight resilience.
• The pedicel separates easily from the stem (in some varieties — with a characteristic "snap").

Important: Do not confuse brown ripeness with "mature-green" (the fruit is completely green but already large). Mature-green fruits ripen poorly: they will not accumulate enough sugars and will remain tasteless.

When to Start Harvesting Brown Fruits

Rely not on the calendar but on the condition of the bush and the weather forecast:

1. 2–3 weeks before expected sustained frosts (in temperate zones — usually late August to early September). From this point on, all fruits that have reached brown ripeness can be safely harvested.

2. When prolonged rains and cold weather set in (below 15°C during the day). In wet, cool weather, ripening on the bush practically stops, and the risk of late blight increases sharply. Harvesting brown fruits in such a situation saves the crop from rot.

3. At the first signs of late blight on leaves — do not wait for the disease to spread to fruits. Harvest all brown and even large green fruits immediately (Gavrish, 2005).

4. If the bush is overloaded and fruits on the upper clusters clearly will not have time to redden before cold weather. Removing lower brown fruits eases the load and accelerates the ripening of upper ones (Mattoo et al., 2017).

Practical rule: as soon as 2–3 brown fruits appear on the lower cluster, start selective harvesting and continue regularly (every 3–4 days) to inspect plantings.

Technique for Harvesting Brown Fruits

• Pick fruits with the pedicel or carefully separate it, leaving a small "tail." This prevents infection from entering through the wound.
• Use pruners or scissors — do not pull fruits off by hand to avoid damaging the stem or knocking off neighboring ovaries.
• Place fruits in wide baskets or boxes in one or two layers so they do not press on each other.
• Sort immediately: brown ones for ripening, mature-green ones can be left on the bush (if weather permits) or also harvested for long-term storage (at 8–10°C).
• Discard damaged, cracked, or spotted fruits — they will rot during ripening and infect neighbors.

How to Properly Ripen Brown Fruits

Ripening is not "ripening" in the refrigerator but a controlled process that requires certain conditions. If followed, the fruits will be almost indistinguishable from those ripened on the bush (Gavrish, 2005, p. 110).

Optimal conditions:

How to organize:

• Spread fruits in one or two layers on shelves, in boxes, or cardboard boxes. Do not stack boxes on top of each other — lower fruits may get bruised.
• The room should be warm (not below 20°C) and dry (without dripping condensation). A pantry, garage (if heated), or veranda will work.
• Every 2–3 days, sort through the fruits, removing any that have started to spoil.
• Full ripening at 23–25°C occurs in 6–8 days. At 18–20°C, the process may take 10–14 days.

How to Speed Up Ripening: Ethylene "Kick-start"

Brown fruits themselves release ethylene, but if there are few of them, the process may be slow. To speed it up, place one or two fully red tomatoes or an apple (or banana) in the box with brown fruits. These fruits release a lot of ethylene and "infect" their neighbors, triggering a chain reaction (Mattoo et al., 2017).

Important: Do not place too many red fruits — excess ethylene can lead to overripening and softening. One or two red tomatoes for 5–10 brown ones are enough.

Why Ripening Does Not Ruin the Taste

Many gardeners fear that ripening produces "watery" and tasteless fruits. This happens only in two cases:

• Fruits were harvested too green (mature-green stage) — they did not have time to accumulate sugars.
• Ripening was done at low temperatures (below 18°C) or at very high humidity.

However, if you harvest brown fruits and ripen them at 23–25°C, they undergo the same biochemical processes as on the bush: starch turns into sugars, organic acids are partially oxidized, and the taste becomes rich. In chemical composition, ripening differs little from ripening on the plant (Gavrish, 2005, p. 110). However, fruits ripened on the bush are often slightly more aromatic due to a greater variety of volatile compounds, but for most practical purposes, the difference is not critical.

What Not to Do During Ripening

When Harvesting Brown Fruits Is the Only Salvation

In regions with short summers (northwest, Siberia, Urals), often by the end of August, many green fruits remain on the bushes that will not have time to turn red before frost. In this case, all large fruits (even mature-green ones) are harvested and laid out for ripening. At 23–25°C, they will turn red in 10–14 days, and at 18–20°C — in 2–3 weeks. The main thing is not to let them get too cold (below 12°C) during storage, otherwise they will remain green (Gavrish, 2005, p. 110).

Summary on brown fruits:

• Brown ripeness is the optimal stage for harvesting: the fruit has already accumulated sugars but is still firm.
• Harvest brown fruits in case of threat of cold, rain, or disease, as well as to unload the bush.
• Ripen at 23–25°C and humidity 80–85%, in one or two layers, with regular sorting.
• To speed up, place a red tomato or apple as a source of ethylene.
• Ripening gives full-flavored fruits if conditions are met.

In the next chapter, we will analyze folk methods for accelerating ripening — which ones actually work and which are myths.

Group 1. Working (Have Scientific Basis)

Group 2. Myths and Erroneous Practices

What Actually Works from Folk Methods — Brief List

Summary on folk methods:

Real acceleration of ripening is achieved through agronomic methods — managing load, nutrition, microclimate, and harvest timing. There are no magical solutions that "force" a green fruit to instantly turn red. Use proven techniques with scientific basis, and your tomatoes will redden faster and more uniformly.

In the next chapter, we will analyze the most common mistakes gardeners make when trying to accelerate ripening.

Mistake 1. Excessive Watering During Ripening

Mistake 2. Continuing Nitrogen Fertilizing in Late Summer

Mistake 3. Complete Removal of All Leaves

Mistake 4. Too Early or Too Late Pinching of Tops

Mistake 5. Harvesting Too Green Fruits for Ripening

Mistake 6. Ripening in the Refrigerator or Cold Basement

Mistake 7. Ignoring Variety Characteristics

Mistake 8. Improper Sucker Removal

Mistake 9. Too Dense Planting

Mistake 10. Ignoring Weather Signals

Summary Table: What to Do Instead of Common Mistakes

Summary of common mistakes:

Most mistakes are related to two extremes: either the gardener intervenes too actively (tears everything off, floods with water, stuffs with fertilizers), or, on the contrary, does nothing when the weather is already against the harvest. The golden mean is regular monitoring and timely but moderate actions. Learn to read the plants and trust proven agronomic techniques, not rumors or "magic" recipes.

Conclusion of the article:

We have traveled from understanding the biology of ripening to specific actions in the greenhouse and open ground, analyzed when and why to remove leaves, how to properly ripen brown fruits, and separated myths from working methods. The main takeaways:

• Ripening is triggered by ethylene, which is sensitive to temperature (optimally 20–25°C), potassium nutrition, and the absence of crop overload.
• The process can be accelerated by managing the microclimate (in a greenhouse) and protecting from weather (in open ground), as well as through reasonable thinning of clusters and removal of excess leaves.
• Do not be afraid to harvest brown fruits — this does not worsen the taste and accelerates the ripening of the remaining ones.
• Avoid extremes: nitrogen overfeeding, total pruning, and ripening in the cold.

May your tomatoes turn red uniformly and delight you with a bountiful harvest!