Agrotechnology for growing early tomato cultivars in protected soil

Early greenhouse cultivars and hybrids sown in January, having been transplanted into nutrient cubes in a timely manner, grow to 18–20 cm by the end of February and set their first inflorescence. At this time, they can be planted in a heated winter greenhouse.

Before planting in a permanent location, plants showing signs of disease or biological inferiority are culled.

In soil that has been previously prepared and allowed to settle slightly, holes at least 10 cm deep are made; the transplants in their cubes are placed into them and covered with good, light soil. 2-3 g of superphosphate is added to each hole beforehand. The soil should not be filled up above the hypocotyl. Early cultivars are usually spaced according to a 50x30 or 50x35 cm pattern.

For better soaking, transplants are removed from their containers and immersed in warm water for 5-7 seconds. Plants should be set into the hole 3-5 cm deeper than they were in the transplant stage.

After planting, the transplants are immediately tied to stakes, and suckers are removed as they grow. When the plants reach a height of 140-150 cm, the lower leaves up to the first inflorescence, as well as any that have begun to yellow or dry out, are pruned. The top of the stem is pinched off above the 6th or 7th inflorescence.

Tomatoes at this stage are watered not often, but abundantly, directing the water straight to the soil, at the root, without splashing it or the fertilizer solution, as tomatoes do not like high air humidity and fall ill from it.

Planting in spring greenhouses with auxiliary heating is carried out from the end of March to the beginning of April; in frame and tunnel covers with solar heating, it begins from mid-May.

Air humidity in the greenhouse should not exceed 60-65%, and the temperature on a clear, sunny day should be no higher than 33 °C, since at higher temperatures the pollen becomes sterile.

To accelerate the warming of the soil under plastic, ash, crushed charcoal, or peat crumbs are spread on the snow. Manure is not used for tomatoes.

Beds 30-35 cm high and 60-90 cm wide (depending on the width of the greenhouse) are made along the greenhouse 5-10 days before planting the transplants. A walkway is left between the beds.

For loamy or clay soil, add 1 bucket of peat, sawdust, or humus per 1 m2. If the beds are made of peat, add 1 bucket of humus, sod soil, and 1/2 bucket of coarse sand and sawdust per 1 m2. It is also necessary to add 3 tablespoons of double granular superphosphate, 1 tablespoon each of potassium sulfate and potassium-magnesium, 1 teaspoon of urea or sodium nitrate, and 2 cups of wood ash or dolomite flour to neutralize acidity. All components are tilled into the soil.

The prepared beds are watered with a warm (30—40 °C) mullein solution (1 L of mullein per 10 L of water) at a rate of 3-4 L per 1 m2.

Then, before planting, the transplants are watered with a potassium permanganate solution (1 g per 10 L of water) at 1-1.5 L per hole.

Tomato transplants are planted when the soil warms up to 16-18 °C. In case of frost, it is necessary to use insulating material (kraft paper, straw mats, or 2 layers of plastic).

Transplants are ready for planting in 50-55 days; by this time, they should have 6-8 leaves and a formed inflorescence. High-quality transplants and early planting in a permanent location ensure an earlier harvest (on average 20-25 days earlier), as well as a 20-30% increase in yield. As a rule, 2-3 plants per 1 m2 are planted in a 40x50 cm pattern (depending on the cultivar).

Non-overgrown transplants (25-30 cm) are planted vertically, covering only the pot with the soil mixture. If the transplants have nevertheless become leggy for any reason, dig holes 12 cm deep and make a depression in them according to the size of the transplant pot. In this case, the first hole is left open. After 12-15 days, as soon as the transplants have established themselves well, the first hole is filled with the soil mixture. This method of planting yields the best results.

Hybrids and cultivars of tall crops are planted 3-4 plants to a row in the middle of the bed or in a staggered pattern 30 cm apart. After planting, the plants are not watered for 10-12 days. This prevents them from becoming leggy and allows their root system to develop well.

To obtain an earlier harvest, determinate cultivar transplants can be planted more densely — 8-10 plants per 1 m2, with the plants formed into a single stem, pinching off above the 3rd or 4th inflorescence.

When planting, the plants are buried up to the first true leaves and tied to stakes, or in a high greenhouse — to a trellis at a height of 180-200 cm, attaching the twine to the base of the plant and the wire stretched above with a slip knot. This allows the twine to be lengthened and the stem of the tomato to be supported. This should be done weekly. Care must be taken not to over-tighten the twine, as the plants could be pulled out by their roots.

When training plants to a single stem, 7-9 inflorescences are left.

A key feature of care is the timely removal of side shoots (suckers) in indeterminate cultivars, which accelerates fruiting. This must be done when side shoots are no longer than 3—5 cm. In determinate cultivars, only the lower side shoots are removed.

To avoid infection with viral diseases, side shoots from leaf axils and root shoots are not cut, but snapped off sideways so that plant sap does not splash onto the fingers, as the disease is transmitted from a sick plant to a healthy one through it. Stubs from side shoots should be left 2-3 cm high; it is best to snap them off in the morning.

Pinching the top of the stem is carried out when growing in a single stem — for the earliest harvest in dense plantings above the 3rd—4th inflorescence, and in indeterminate cultivars above the 8th—10th inflorescence. In all cases, 1-2 leaves are left above the inflorescence, which contributes to better fruit filling.

When growing determinate cultivars and hybrids of tomato for a long period, it should be remembered that due to their biological characteristics, they are prone to "topping," i.e., growth limitation by an inflorescence. If all side shoots are removed by that moment, the plant's growth ceases. To prevent this, a backup side shoot is left, which becomes a continuation of the stem upon topping. The backup side shoot can be a shoot from the axil of a leaf located under one of the top inflorescences. If the stem growth is not limited by an inflorescence, the side shoot is removed, and a new backup side shoot is left closer to the top. With regular side shoot removal (once a week), the backup side shoot does not have time to overgrow and does not worsen the condition of the plant.

Leaving additional side shoots in indeterminate hybrids significantly increases labor costs. Fruit set at the inflorescences on the main stem is poorer, the plants become severely overcrowded, which ultimately leads to a decrease in yield and the spread of fungal diseases (especially gray mold). Additional rooting of side shoots also provides no advantages. It often even reduces yield and requires significant expenditure of materials and labor.

For better pollination in the greenhouse, a draft is created or the plants are shaken by hitting the trellis wire.

To increase the yield of early harvest, one can use the experience of practitioners who recommend "feeding" plants in unheated greenhouses with a nutrient solution warmed to 25 °С. In this case, the harvest from the first three fruit clusters of the plants increases by 200 g, and the output of early harvest — by 10-12%. To prevent fruits from becoming smaller, the clusters of tomatoes must be thinned, leaving 3—5 fruits in each.

To obtain a good harvest, 10-15 top dressings are carried out. The first one is done after the transplants have established: for 10 l of water, take 16 g of ammonium nitrate, 50 g of superphosphate, and 10 g of potassium chloride. Subsequently, before the start of fruiting, dissolve 9, 25, and 15 g of fertilizers in 10 l of water, respectively. During the fruiting period, the amount of nitrogen is doubled. On old soil, top dressing is applied less frequently, on new soil — more often. Usually, 10 l of solution is enough to water 3—4 m? of the plantation. After each top dressing of plants, the plantings must be sprayed with clean water.

Yield is increased by spraying plants with micronutrients: 0.04% manganese sulfate, 0.02% each of copper sulfate, boric acid, zinc sulfate, and 0.003% ferric citrate. Tomatoes are also watered and fertilized with basic phosphorus-potassium fertilizers, applying them as a solution directly into the soil around the plants, avoiding wetting the leaves and stems.

Air humidity in the greenhouse should be kept at the lowest possible level. In addition to increased ventilation, compost is applied, and the soil is mulched with sphagnum moss or peat, which absorb moisture well.

When growing tomatoes under plastic film, in a small greenhouse, in a "tent," or simply under a plastic frame, the air should not be allowed to heat up above 30 °С, as fruit set will not occur and the plants will stretch excessively. The temperature is regulated by ventilation and kept at 22-26 °С on sunny days (5—6 °С lower without sun), and no lower than 12—13 °С at night. If the night is warm, the plants are not covered at all.

A greenhouse intended for tomatoes must have vents not only on both sides but also at the top (1—2), as plants, especially during flowering, require thorough ventilation.

The greenhouse should be fully illuminated by sunlight from morning to evening; even slight shading by fruit trees or bushes negatively affects yield.

Carbon dioxide top dressing is very helpful in greenhouses: 10 g of dry ice per 1 m³ of greenhouse space. It is best to perform gas enrichment in the morning.

The harvest is collected as the fruits ripen. It is best to pick them at the breaker or pink stage of ripeness and then let them ripen in a dry, warm room: on a terrace, in a room, or in an attic.

As tomato fruits ripen, the lower leaves are removed. This increases the illumination of plants within the row, which is necessary for improving photosynthesis, and improves air exchange, which reduces air humidity and decreases disease incidence, as old leaves are more easily affected by fungal diseases. A plant should have 13–18 leaves, including young ones; leaves should be removed up to the truss on which fruits have started to ripen.

Remember that excessive leaf removal will lead to a decrease in yield, as tomato fruits are formed by the products of photosynthesis delivered to them by 2–3 leaves located above the truss.

It is standard practice to form plants of early-ripening cultivars into 2–3 stems. The second stem is formed from a sucker located in the leaf axil under the first (bottom) inflorescence, and the third from a sucker of a leaf located below or from a sucker located in the leaf axil under the second inflorescence. It is acceptable to form the plant into one stem by removing all side shoots. In this case, transplants should be planted densely — 6–8 plants per 1 m².

Determinate cultivars form 4–6 inflorescences on the main shoot, after which the stem growth ceases.

The first inflorescence is set above the 7th–9th leaf, and subsequent ones are located every 1–2 leaves. This group is represented mainly by modern first-generation hybrids, which hold a leading position both in commercial plantings and in private gardens due to many properties: extraordinary plasticity (they can be grown in all regions, and in the middle latitudes, good results are obtained even in open ground), high yield, earliness, uniform fruiting, and complex disease resistance.

Hybrids of the determinate type are unique in their biological characteristics and therefore require an individual approach, especially when forming the plants.

The simplest method is to leave 1–2 reserve suckers in the upper part of the plant after the formation of 4–5 inflorescences. When stem growth is restricted, the reserve sucker replaces

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Diagram of tomato plant formation (Roman numerals indicate the sequence numbers of inflorescences, Arabic numerals indicate the sequence numbers of leaves) 209 it. The second sucker must be removed. It should be remembered that the strongest shoot always develops in the axil of the leaf located directly below the inflorescence. This is the one that should be left.

Sometimes suckers overgrow, and flowers bloom on them; fruit set may even occur. Some gardeners let them develop. But it is a problem if there are several such overgrowths. The plant becomes overgrown, and fruit growth drops sharply. Therefore, if a reserve sucker was not used to form the continuation of the shoot, it should be removed in time.

In commercial plantings, as well as by experienced gardeners, the method of transferring the stem to a side shoot is used. This technique is carried out as follows:

• a continuation shoot is formed from the sucker of the leaf located directly below the fourth inflorescence;
• 5–6 inflorescences are left on the main stem, and it is pinched;
• the next shoot is formed on the continuation shoot from the sucker of the leaf located below the first inflorescence;
• it is pinched after the 2nd–3rd inflorescence, and the plant's growth is transferred to a new side shoot.

By using this formation method, it is possible to increase the number of fruit-bearing inflorescences by two times or more. It is advisable to use the method of transferring growth to a side shoot during long growing seasons of determinate hybrids — in glass or heated greenhouses and in southern regions.

Determinate tomatoes have a relatively small leaf apparatus. The root volume is also small. Therefore, the plant is unable to provide all growing fruit sets with nutrients.

Hybrids of the determinate type require mandatory top dressing with mineral fertilizers, which should begin during the period of fruit set formation on the 1st–2nd inflorescence.

Gardener Y. Vinogradov from the Moscow region is fond of growing tall tomato cultivars. These cultivars are characterized by continuous stem growth and an extended fruiting period. When grown in greenhouses, they significantly outperform low-growing cultivars in yield.

Continuous growth of the stem leads to the fact that even in the middle regions in unheated greenhouses, plants reach a height of 2–3 m by August. Subsequently, one has to move the growth of stems to a horizontal position or even lower the top of the growing stem, which is, of course, unnatural for the plant and reduces its productivity.

Some enthusiasts build greenhouses 3 m high or more for growing tall tomatoes, but this only leads to increased consumption of building materials. Meanwhile, there is a so-called "Danish" method that allows for growing long-stemmed tomatoes in a greenhouse of low height.

The essence of the method lies in the fact that the tomato plant, grown as a single stem and having reached the top of the greenhouse, is subsequently lowered together with the twine around which the stem is wound. Before lowering, old leaves and ripe fruits are necessarily removed from the lower "spent" part of the stem.

The stem is lowered due to the fact that there is a supply of twine on a special hook, which is attached to the trellis wire stretched under the greenhouse roof. The stem is lowered, and the hook is moved along the trellis wire in a horizontal direction. The top of the plants with 10-15 leaves and growing fruits continues to fruit. When it reaches the top of the greenhouse again, the stem is lowered once more. Thus, the stem growth always continues in a natural vertical direction, and the method provides a yield increase of up to 20-40%.

Diagram of the "Danish" method of growing transplants: 1 — hook with a supply of twine; 2 — direction of stem placement;

With the "Danish" method, plants are planted in a bed in 2 rows with a distance of 40-50 cm between plants in a row. A net is stretched over the bed at a height of 20-25 cm, onto which the stems of the lowered plants rest. All plants of one row are laid in one direction, and those of the other — in the opposite direction. When the laid stem reaches the edge of the bed, it is turned and transferred to the other row.

With the "Danish" method, plants are grown in a single stem, removing all side shoots (suckers).

A small universal unheated greenhouse has been specially developed for growing tall tomato cultivars using the "Danish" method, which can be easily re-equipped for various tomato growing methods.

Greenhouse construction, drip irrigation, and bush staking

For growing tall tomatoes, reliable fixation of the bushes is important. Staking is performed using a horizontal cable stretched over the plants. Vertical sections of twine or fishing line with loops every 20–25 cm are attached to it, into which wire hooks are inserted. The stem or fruit cluster is supported by rings made from an old bicycle inner tube, which are folded in half and hung on the hooks. With this method, the bushes do not break under the weight of the fruits and develop freely.

The collapsible greenhouse with an area of 10 m² is assembled from individual wooden sections. Each section consists of two uprights and a triangular truss roof, reinforced with internal struts for stability under the harvest load. Metal spikes are attached to the bottom of the uprights for anchoring into the soil. The sections are connected by three longitudinal battens — along the ridge and the tops of the uprights. The rigidity of the structure is provided by diagonal braces made of aluminum wire in each opening, after which the frame is covered with polyethylene film.

For good fruit set, it is necessary to control the humidity and air temperature. Ventilation openings are left at the top and bottom in the ends of the greenhouse, which are covered with film only during the threat of frost. To reduce air humidity and preserve soil moisture, the beds are mulched with polyethylene film. Drip irrigation hoses connected to a tank inside the greenhouse are laid under the mulch. The water in the tank heats up during the day, and evening irrigation is started by simply opening a tap, eliminating the need for weeding and loosening.

• Greenhouse size — 2,5х4 m
• Height at the ridge — 2,3 m
• Bar cross-section — 40х40 mm
• Loop spacing on the twine — 20–25 cm
• Temperature threshold for fruit set — up to 30 °C

Protecting tomatoes from damping off, late blight, and white spot disease

The main threat to young tomato transplants is damping off. The pathogen of this fungal disease persists in the soil, causing darkening, thinning, and rotting of the stem. To prevent plant loss, it is necessary to strictly follow a set of preventive measures. Plant protection includes seed treatment, soil processing, and microclimate control.

1. Perform seed treatment in a 1% potassium permanganate solution (1 g per 100 ml of water) for 20–30 minutes, then rinse with water and dry until free-flowing.
2. Add TMTD preparation to the potting soil mixture at a rate of 7–8 g per 10 kg of mixture or thoroughly steam the soil.
3. Ensure good ventilation and irrigate seedlings exclusively in the morning at the edge of the pot, avoiding wetting of stems and leaves.
4. Maintain the temperature regime in accordance with the seedling development phase and light levels.

Upon detection of the first signs of blackleg, diseased plants are immediately removed. The soil is disinfected with a pink solution of potassium permanganate, then covered with wood ash or calcined sand in a layer up to 2 cm thick. For complete sanitation of nursery beds, the soil is replaced or treated with a 40% formalin solution at a rate of 0.2 l of preparation per 10 l of water, with an application rate of the working solution of 1.5–1.7 l per 1 m².

In damp and cold weather, tomatoes are affected by late blight. The fungus overwinters on plant debris and potato tubers, rapidly activating in high humidity. At the first signs of darkening of leaves and fruits, the planting is treated with garlic infusion: 100 g of dried leaves and husks are infused in 10 l of water for 24 hours. Spraying is repeated 2–3 times at intervals of 5–7 days. Significant damage is also caused by white spot, where brown spots appear on the lower leaves, turning into dirty white, which leads to their drying out.

Brown and dry spot are dangerous fungal diseases that quickly deprive tomatoes of their leaf canopy. Brown spot is first noticed on the underside of leaves, where light-gray velvety blurred spots appear. Gradually they darken, and light-green, then browning foci form on the upper side of the leaves. With severe spread of the disease, the leaves begin to dry out.

Dry spot manifests as brown rounded or irregular spots on the lower leaves of tomatoes. Gradually, the disease spreads to the upper leaves of the plant. As a result of the disease spread, tomato fruits also become infected.

Methods of tomato protection and recipes for working solutions

• Application rate of copper-based solutions — 1 l per 1 m²
• Garlic infusion period — at least 72 hours
• Concentration of Bordeaux mixture — 1%
• Concentration of Burgundy mixture — 0.5%

For reliable prevention and control of spots, the agronomist must regularly carry out a complex of protective treatments. This includes mandatory seed treatment before sowing and disinfection of the greenhouse soil. Vegetating plants are sprayed with copper-based preparations, including the classic 1% Bordeaux mixture.

Alternatively, a 0.5% Burgundy mixture can be used. To prepare this working solution, it is important to strictly observe the dosage of active ingredients. The necessary amount of components for preparing the mixture is indicated in the table below.

1. Prepare solutions of copper sulfate and soda ash in separate containers according to the specified proportions.
2. Pour both prepared solutions together into one container.
3. Add 10 g of sugar to the resulting mixture to improve adhesion to the leaves.

Against tomato pests — aphids, mites, and thrips — garlic infusion shows high effectiveness. This remedy is prepared based on crushed garlic cloves and laundry soap. The working solution is used for foliar spraying of the plantings.

1. Finely chop and crush 150 g of garlic cloves, then cover them with 3 l of water.
2. Close the jar tightly with a lid and keep the infusion in a dark place for at least 72 hours.
3. Immediately before use, carefully filter the resulting liquid.
4. Dilute 1–1.7 cups of the finished infusion in 10 l of water and add 40 g of laundry soap.