Why do the leaves of tomato seedlings turn yellow?

At home, the leaves of tomato seedlings sometimes turn yellow. Why this happens and what to do about it is described in the article.

Causes of yellowing seedlings

The main reasons for yellowing of seedlings on the windowsill are: improper carewhen one or more growth factors are deficient. The main reasons are:

1. Lack of light.
2. Too bright spring sun.
3. Incorrect watering.
4. Thickened crops.
5. Tight containers.
6. Incorrect feeding.
7. Unsuitable soil.
8. Picking.
9. Landing in the ground.

Tomatoes during the seedling period are quite unpretentious and it is not difficult to correct all negligence in care, if they have not gone too far.

reason 1. Lack of light

Tomatoes are light-loving plants, so when grown on a window, especially on the north side, they always lack light. In cloudy weather, even with backlighting, there is little light for them. Due to low light, tomatoes stretch out and their lower leaves begin to turn yellow.

How to fix the situation. It is always advisable to grow tomatoes in the brightest window. Seedlings up to 30 days of age are always illuminated, especially late varieties that are sown 2 weeks earlier. If it is cloudy outside, then additional lighting is provided 16 hours a day. If the weather is sunny and the tomatoes are grown on a southern windowsill, then illumination for 12-14 hours a day is sufficient. In addition, to enhance the illumination, a reflective film, foil or mirror is placed behind the seedlings.

If the days are cloudy and the tomatoes on the windowsill have turned yellow, despite additional lighting, then it is extended to 18-19 hours a day. In addition to the lamps for illumination behind the seedlings, you can place a table lamp. In difficult situations, this often turns out to be a decisive factor for the normal development of tomatoes.

reason 2. The sun is too bright

Signs of damage. White dry spots appear on the leaves. They can be located either along the edge of the leaf blade or in the center. The tissue at the site of damage dries out, becomes thinner and resembles parchment paper in color. The plant itself becomes pale in color and, in severe cases, turns yellow.

Burn Prevention. If the burn is very severe, then the damaged specimen cannot be saved - it will dry out. The rest of the seedlings are removed from the window in a bright place, but without direct sunlight. When the tomatoes become a natural green color, they are returned to the same window, but be sure to shade them.

To prevent yellowing of seedlings in a greenhouse, they must be shaded. Light shading should remain after planting the seedlings in the ground for 5-7 days.

reason 3. Improper watering

This is the most common reason. Both a lack and an excess of moisture leads to the appearance of a yellow tint to tomatoes. As the situation worsens, the tomatoes turn yellow, starting from the lower leaves. If there is not enough moisture, the leaves first hang and then dry. With excess moisture, the leaves also lose turgor and turn yellow, but do not dry out.

What to do. If the tomatoes on the windowsill have turned yellow due to insufficient watering, they should be watered immediately, but moderately. As a rule, after this the natural color of the plants is restored, and they then develop normally.If some of the leaves have already curled, they will still dry out and need to be torn off.

With excess moisture the situation is more complicated. Tomatoes recover more slowly after waterlogging. Watering is completely stopped until the soil dries out. In severe cases, tomatoes will have to be planted in a larger container with the addition of dry soil. After picking, the plants are not watered for 5-7 days. After waterlogging, yellowness remains for 7-10 days.

4. Thickened crops

If the crops are heavily thickened, the seedlings may turn yellow already at the stage of the first true leaves. But usually this happens as it grows.

Tomatoes look thin, frail, their lower leaves are yellow, the upper ones are light green with a yellowish tint.

Elimination of causes. Seedlings are planted in separate containers. If the tomatoes are growing in separate containers, but they are cramped and their leaves are touching, then they are placed freely on the windowsill. Then they stop competing with each other and begin to develop normally.

5. Tight containers

Signs. The lower leaves acquire a yellowish tint, and as the situation worsens, they become bright yellow. If the plant is not picked, then all this quickly spreads to the overlying leaves, and the tomatoes themselves acquire a green-yellow color.

Restoration of tomatoes. The only way to correct the situation is to plant the seedlings in larger containers. The roots that have grown along the perimeter are removed because they are not functional. The rest are reduced by 1/4, filled with fresh soil and dived.

After picking, the leaves of the seedlings may turn yellow even more. But this is a short-term phenomenon. After a few days, new roots will appear and the tomatoes will continue to grow. As the young roots grow, the tomatoes will become stronger and the plants will acquire a natural green color.

It should be noted that tomatoes recover quickly. After some time, the dishes may again turn out to be small, and the tomatoes on the window will begin to wither again. It is better not to carry out a second picking, but to immediately plant the plants in a permanent place. If the time is not yet right for this, then you will have to pick them again, but you should not shorten the roots.

6. Incorrect feeding

Seedlings may have a pale appearance if there is no nitrogen fertilizer in the fertilizing. With a lack of nitrogen, especially if incorrectly selected soil is added to this, the seedlings on the windowsill become small, thin, weak and greenish-yellow.

What to do. At home, tomatoes are always fed with complex fertilizers, which should contain nitrogen. No matter how well the soil is fertilized, during the seedling period tomatoes need additional feeding, which contains all the nutrients.

For fertilizing, you can use both special complex fertilizers for tomatoes and fertilizers for indoor plants in which the nitrogen content does not exceed 10%.If there is more of it, then the tomatoes will quickly begin to gain green mass and stretch out (since they do not have enough light in any window). As a result, they weaken and outgrow.

7. Unsuitable soil

If the soil is selected incorrectly, seedlings on the windowsill suffer from nutrient deficiency and, as a result, turn yellow. Tomatoes require slightly acidic soil (pH 5-6).

If the soil is alkaline, then tomatoes grown in the window often experience iron deficiency. The leaves become yellowish with dark green veins. This is more pronounced on the lower leaves.

If the soil is too acidic (for example, a peat mixture), then a deficiency of all elements appears, with the same consequences.

Restoration activities. First of all, you need to find out the pH of the soil mixture in which tomatoes are grown, since the measures for influencing alkaline and acidic soils are different. But since stores do not sell soils for seedlings with a pH above 7 and below 4.5, this greatly simplifies the situation.

If alkaline soil (the main symptom is iron deficiency, pH 6.5-7):

• tomatoes are watered with a slightly pink solution of potassium permanganate, which reduces the alkalinity of the soil;
• When picking seedlings, peat is added to the container, which perfectly reduces the alkalinity of the soil.

The soil is acidic. After planting in the ground, tomatoes can tolerate a slight increase in acidity. But during the seedling period, especially in cramped containers, they are sensitive to acidic soil.If all the tomatoes on the windowsill turn yellow for no apparent reason, although they look healthy and receive proper care and feeding, then the problem is in acidic soil. Plants become yellowish-green, evenly colored.

To eliminate acidity, tomatoes are watered with fertilizers:

• infusion of ash;
• chalk or plaster solution.

There are now many drugs on sale in stores that lower the pH of the soil, which are used in accordance with the instructions.

8. Picking

After picking, tomatoes are always fade slightly. But if the roots are also damaged, then yellow spots appear on the leaves, which quickly spread over the entire surface, and the lower leaves may dry out. However, plants recover quite quickly even with severe damage to the root system. After 3-4 days they are already developing normally. With minor damage to the roots, tomatoes can easily tolerate the procedure. Their lower leaves droop slightly, but this goes away after 4-5 hours.

However, if more than half of the roots are damaged, the plant dies. The only thing that can be done is to water the tomatoes with the root formation stimulator “Kornevin”. But if the leaves begin to curl and dry out after picking, the plants cannot be saved.

Another reason for yellowing of the leaves is that, a few hours after picking, the tomatoes were placed on a window in direct sunlight. Even if the leaves have not drooped, the plant is still sick. If at this time it comes under the rays of the sun, the evaporation of moisture from the surface of the leaves will increase significantly.But the root system has not yet recovered and cannot ensure normal flow of water to the above-ground part.

As a result, the lower leaves droop and become yellowish. To prevent tomatoes from wilting, they can be placed in the sun only 1-2 days after picking.

9. Planting seedlings in the ground

Sometimes this kind of trouble happens right away after landing in the ground. This occurs due to a sharp change in growing conditions. At home on the windowsill it grew in relatively comfortable conditions with minimal fluctuations in day and night temperatures. After planting in the ground during the day, it is always much warmer in the greenhouse than in the window, and at night it cools down greatly. Temperature fluctuations in a greenhouse or greenhouse can be 15-20°C.

If the yellow tint persists for more than 7 days and the tomatoes do not grow, it means that their roots were severely damaged during planting. You should water the plants with Kornevin or Kornerost solution. If the situation does not improve within a week, then the roots are very damaged. Most likely, such seedlings will not take root. Even if it improves, the harvest will be significantly smaller.

Sometimes already yellowed seedlings are planted in the ground. If she is healthy, but she was already cramped on the windowsill, there was not enough moisture, or she was growing in cramped containers, that’s why she looks so unhealthy. Such tomatoes adapt very quickly and begin to develop quickly. If the lower leaves turn completely yellow, they will dry out and fall off. This is a natural phenomenon and there is no need to worry.

Continuation of the topic:

1. Diseases and treatment of tomato seedlings
2. How to properly feed tomatoes in a greenhouse and outside
3. Why do tomato leaves curl?
4. Rules for planting tomatoes in open ground
5. When can you plant seedlings in open ground?
6. Caring for tomatoes in open ground
7. Planting tomato seedlings in a greenhouse