Purple leaves in tomato seedlings: causes and methods of struggle

By certain external signs one can find out if the plant is experiencing a deficiency of useful elements.Purple tomato leaves are the result of a lack of phosphorus, nitrogen or potassium. Less commonly, the cause is cold ground or lack of water. To fix the problem, the gardener needs to know what methods to deal with it.

Tomatoes grow well in warm regions with air temperatures from 21 to 24 ° C. They require loamy, well-drained soil with a pH between 5.5 and 6.8. Like all fruit plants, tomatoes need the sun for most of the day.

Compared to the lack of other nutrients, the symptoms of phosphorus deficiency are usually not very noticeable and can be difficult to determine. In tomato seedlings, leaves become purple or lilac from below, which is an unnatural color for tomatoes at any stage of growth. Sometimes the gardener notices that the bush does not grow well. The underside of older leaves shows a purple pigmentation brighter. However, in some cases, no obvious symptoms on the leaves are observed, the color change is not noticeable, if you do not look closely.

In tomatoes, the leaf is not only blue, but can also become leathery, and the veinlets form a brown grid. It becomes clear that the purple hue appeared for a reason. In tomato seedlings of some varieties, phosphorus deficiency is characterized by burnt tips and the development of chlorosis, as well as necrotic spots on the edges of the leaves. There are flowers, but the yield is low.

In advanced cases, plants can not bloom, despite the fertile soil, watering, feeding, and this may be the result of nutritional deficiencies. Violet leaves with a bronze or brown edge indicate an excess of moisture or a lack of potassium in the soil. The reddish-purple undersides of the leaves, combined with slow growth, indicate phosphorus deficiency due to cold or acidic soil.

If we talk specifically about the lack of phosphorus, then the plant has the following symptoms:

• usually affects the lower first leaves of the plant;
• the cover darkens (dark green, blue, purple or grayish) and looks brilliant;
• leaves may begin to turn yellow if phosphorus deficiency is combined with a lack of other nutrients or pH problems;
• bronze, purple or brown spots appear;
• the stems sometimes turn bright red or purple, but not always.

Phosphorus is an essential element for plant growth and development. When other nutrients enter it, phosphorus helps turn them into useful building blocks (proteins and nucleic acids). It is an intermediary between two types of energy in the metabolic process.

Phosphorus is important during each step of the life cycle:

• in seedlings promotes healthy root development;
• in young plants provides strong stems and leaves;
• during flowering and formation of ovaries contributes to the development of fruits;
• during ripening improves the nutrition of tomatoes.

Consider the main causes of violet leaf color seedlings. In most cases, this is due to the lack of nutrients.

Causes of phosphorus deficiency:

• insufficient use of fertilizers and organic matter;
• non-compliance with the temperature regime;
• low fertilizer use due to soil erosion;
• immobilization in Ca phosphates due to excessive liming;
• unbalanced use of fertilizers.

Some soils are naturally low in phosphorus. It is a calcareous alkaline soil in which calcium is present in high concentration. The optimum pH for tomato growth is 6.5-6.8.Soils that are low in organic matter or rich in iron can also be problematic. Phosphorus is necessary for growth, cell division, elongation of roots, seeds, and fruit development. It is part of several compounds, including oils and amino acids.

There are differences in susceptibility to phosphorus deficiency between different tomato varieties. If the field has been treated properly, residual fertilizer from previously grown crops can provide the next crop with sufficient phosphorus.

Sometimes phosphorus goes into an insoluble form, even if it enters the soil in liquid form. This happens when a large addition of ash in the ground. In this case, the mineral is not only not absorbed by the plant, but also inhibits its development. It is easy to check the element surplus: it is enough to sow a radish in this place at the beginning of spring, which will start abundantly shoot if phosphorus is present in the soil in excess.

Another reason for the appearance of purple color - cold or wet weather, which prevents the proper development of the roots. Planting tomatoes outdoors too early or in a greenhouse where it is cool, can cause the leaves of young plants to be purple. This is a short-term problem, but may affect tomato growth.

No matter how strange it may sound, but pets also have a negative impact on the development of plants. Their urine contains a component harmful to tomatoes, especially it is necessary to allocate cats.

Another reason could be a virus infection, which is easily transmitted from beets or small insects that inject their saliva into the leaves, hence the change in color. Listabloshki are small flying insects. They are easy to detect, as they are usually present in large quantities.

The earliest symptoms of infection are a slight yellowing and / or purple color of the upper leaves. Lower tend to slightly curl upwards. With a strong infection, the entire top of the plant changes to a reddish-purple, sometimes yellowish-green. These problems are solved using special chemicals that spray plants.

Detection of phosphorus deficiency can be difficult. Most soils contain some element, which may be sufficient to prevent the visible symptoms of deficiency, even if the current level is too low to maintain healthy growth of vegetables. To prevent deficiency, you can use ready-made mixtures that are inexpensive and easy to use. Phosphorus is applied to plants in the form of phosphate along with nitrogen and potassium (trio N-P-K in fertilizer products).

Soil testing is recommended to determine the ratio of each of these nutrients. Before planting, phosphorus and potassium are usually recommended. Nitrogen must be introduced later during vegetative growth. Phosphorus improves the quality of vegetables and the efficiency of soil absorption of water.

Sources of phosphorus:

• organic fertilizers;
• animal droppings and humus;
• mineral fertilizers;
• superphosphate, diammonium phosphate;
• bio-fertilizers;
• solubilizing phosphate bacteria, mycorrhiza.

You can control the process of feeding, using organic sources such as phosphate or fish fertilizer. Plants that are adapted to low levels of available soil phosphorus are likely to suffer from phosphate poisoning. In this case, it is necessary to ensure the optimum level of phosphorus for the plant. But the sense of proportion comes to the gardener only with experience.

It is important to know the following principles.

• Any change in leaf color indicates a problem.The best prevention is taking care of plants at the stage of their growth. The gardener is obliged to provide the optimum temperature, since it largely affects the development of tomatoes.
• Tomatoes are heat-loving inhabitants of the vegetable garden, they do not like sudden cold snaps, but there is a good remedy - hardening. Seedlings can be taken out at night, but only if the air temperature does not fall below 18 degrees. This method will help prevent the likelihood of a violet hue afterwards.
• To avoid pests and prevent diseases, it is necessary to spray the plants on time.
• Treatment of phosphorus deficiency will require adding an element to the soil in such a way as to saturate the tomatoes, but not harm them. This is important because the tomato loves extra food, like any fruit-bearing or flowering plant. When phosphorus levels become high, other problems may occur.

• Use fertilizer that comes in the form of powder or granules. Do not put phosphate on plants that do not produce vegetables, and do not add the element directly to the water.
• Although phosphorus can play a major role in the growth of fruits and the appearance of inflorescences, much attention needs to be paid to maintaining balance in the soil. It is important not only to eliminate the deficit, but also to prevent problems in the future.
• As a rule, phosphorus should be added only once per plant growth cycle. You can use it as needed along with calcium and magnesium. The excess will prevent the plants at a certain stage of development to absorb other key nutrients that threaten the emergence of new problems.

The first signs may appear in the interval 6-8 weeks after germination of the seeds. A competent agricultural technician can fix everything before irreversible consequences occur.

About why the leaves of tomato seedlings turn purple, see the next video.