Tomatoes in Open Ground: Complete Practical Guide

2.1 Sunlight – priority number one

Tomato is a plant that “works” on sunlight. The more light, the sweeter and larger the fruits, the higher the yield.

• Choose the sunniest spot. Tomato needs at least 6‑8 hours of direct sunlight per day (Jones, 2008). This is the golden rule. If your plot is shaded even for a few hours a day by trees, buildings, or fences, the plant will stretch, delay flowering, and fruits will be small and sour.
• Bed orientation. If the terrain allows, arrange rows from north to south. With this orientation, plants will be evenly illuminated throughout the day (Balashev and Zeman, 1981). If the bed is on a slope, prefer a southern or south‑eastern slope – they warm up fastest and receive more solar energy in the morning hours, which is very important for the start of the growing season.
• Reflective light. For maximum efficiency, you can use techniques that increase illumination. For example, covering the soil with white mulch or film. This simple agronomic practice reflects light onto the underside of leaves, improving photosynthesis and increasing yield by 10‑15% (Akhatov, 2010).

2.2 Wind protection – protection from dehydration

Strong, especially dry, wind is a serious stress for tomatoes.

Why it is bad: Wind increases evaporation of moisture from leaves (transpiration). The plant, trying to compensate for water loss, may close its stomata, which stops photosynthesis. In addition, wind mechanically damages leaves and can break stems and branches, especially of tall varieties. The result is a weakened plant, poor yield, and reduced disease resistance.

Natural and artificial barriers: The ideal place is a wind‑sheltered area. Good “windbreaks” can be:

• Curtains: Natural or artificial plantings (e.g., a row of sunflower, tall‑stalked corn) on the windward side that create a barrier to the wind.
• Hedges: Shrubs or trees, but the distance from them to the bed must be sufficient so that they do not shade the tomatoes.
• Fences and walls: A solid fence or building wall can reflect sunlight and heat, additionally warming the area, but it is important that the fence does not create strong shading.

Practical conclusion: If your plot is exposed to all winds, consider planting curtain crops or installing light shields on the windward side. This will significantly improve the microclimate for your tomatoes.

2.3 Drainage and soil structure

Tomatoes categorically do not tolerate stagnant water. Over‑moistening of the soil is a direct path to the development of root rots (such as phytophthora) and plant death (Jones, 2008; Heuvelink et al., 2020).

• Drainage: The planting site should be well‑drained. Avoid lowlands where water accumulates after rains. If you are forced to plant in such a place, the only option is to make raised beds.
• Soil structure: Tomato is not demanding on the mechanical composition of the soil, but prefers loose, aerated loams or sandy loams (Balashev and Zeman, 1981). On heavy clay soils, which warm up slowly and tend to become waterlogged, the plant will suffer greatly. In this case, it is necessary to improve the soil structure by adding organic matter and sand.

2.4 Crop rotation – protection from diseases

A very important point that is often underestimated.

• Do not plant tomatoes in the same place. Tomatoes, like other nightshades (potatoes, peppers, eggplants), share similar diseases and pests. If you plant tomatoes in the same place every year, pathogens accumulate in the soil, in particular, the causative agents of Fusarium wilt, late blight, and nematodes (Blancard, 2012; Jones, 2008).
• Best predecessors: It is advisable to return tomatoes to their original place no earlier than after 3‑4 years. This is also called the “rest period” for the soil. The best predecessors for tomatoes are crops not belonging to the nightshade family: cabbage, cucumbers, squash, onions, legumes (peas, beans) and green manures (Balashev and Zeman, 1981; Gavrish, 2005).

2.5 Considering the microclimate of your plot

Even within one plot, conditions can vary. Pay attention to details:

• “South wall”: The spot near the south wall of a house or fence is the warmest, as the wall accumulates solar heat and releases it at night. Here tomatoes will feel especially comfortable and produce an earlier harvest.
• Elevations: If you have a choice, plant tomatoes on a slight elevation. Cold air, as is known, flows down into lowlands, and frosts occur there much more often and more severely.
• Shading from dew: On open flat areas, plants in the morning hours take a long time to dry after dew, which promotes the development of fungal diseases. On elevated or well‑ventilated areas, this problem is less pronounced.

2.6 Practical checklist for site selection

1. Sun: The plot receives at least 6‑8 hours of direct sun.

2. Wind protection: There are natural or artificial barriers to wind.

3. Drainage: The soil does not retain water after rain, water does not stand.

4. Predecessors: In the last 3‑4 years, tomatoes, potatoes, peppers, or eggplants have not grown on this spot.

5. Slope: Southern or south‑eastern slopes are preferred.

3.1 Soil analysis and pH adjustment

Before applying fertilizers, it is important to understand what you are working with. Tomatoes prefer soil with pH between 6.0 and 6.5 (Jones, 2008; Heuvelink et al., 2020). It is in this range that all major nutrients (nitrogen, phosphorus, potassium, calcium, magnesium, and micronutrients) are in a form available to the plant.

Why it is important: If pH is below 5.5 (acidic soil), aluminum and manganese become toxic to plants, and the availability of phosphorus, calcium, and magnesium decreases sharply. If pH is above 7.0 (alkaline soil), iron, zinc, and manganese become unavailable, causing chlorosis (yellowing of leaves) (Jones, 2008; Gavrish, 2005).

How to test: The most reliable way is to conduct an agrochemical soil analysis in a laboratory. For amateur gardeners, portable pH meters or indicator strips sold in garden centers are also suitable.

How to correct:

• For acidic soils (pH < 6.0): Apply dolomite flour or lime. Dolomite flour is preferable because it contains magnesium, which is often deficient in acidic soils. It is better to apply lime in autumn under digging, as the neutralization process takes several months (Jones, 2008).
• For alkaline soils (pH > 7.0): Apply acidic organic fertilizers (high‑moor peat, coniferous litter) or use physiologically acidic fertilizers (e.g., ammonium sulfate). However, dramatically changing pH towards alkaline is difficult; it is easier to organize raised beds with imported soil.

3.2 Application of organic fertilizers – the basis of fertility

Tomatoes are a crop with intensive nutrition. To obtain a rich harvest, the soil must be rich in humus and organic matter. Organic matter improves soil structure: it makes it loose, air‑permeable, and moisture‑retentive.

When to apply: It is best to apply organic matter in autumn, under deep digging. Over winter and spring, it will have time to decompose and turn into humus available to plants (Jones, 2008). However, it can also be applied in spring, 2‑3 weeks before planting seedlings.

What to apply:

• Well‑rotted manure or compost: Application rate – 4‑6 kg per 1 m² (Gavrish, 2005). This is a universal and valuable fertilizer. Important: fresh manure should never be applied to tomatoes! It causes “luxuriance” – vigorous growth of green mass at the expense of fruiting, and can also be a source of diseases and weed seeds. Use only well‑rotted manure (at least 1‑2 years old) or compost.
• Green manures (cover crops): This is a very effective and environmentally friendly way to improve the soil. In autumn or spring, sow mustard, phacelia, rye, or vetch on the bed. 2‑3 weeks before planting tomatoes, mow the green mass and incorporate it into the soil to a depth of 10‑15 cm. Green manure enriches the soil with nitrogen, improves its structure, and suppresses weed growth (Jones, 2008).

3.3 Drainage and soil structure – roots must breathe

The root system of tomato does not tolerate stagnant water. In waterlogged soil, roots suffocate, begin to rot, and the plant becomes easy prey for pathogens.

• Deep digging: In autumn or early spring, dig the soil to a depth of 20‑25 cm (spade depth). This improves aeration, promotes the penetration of air and moisture into deep soil layers, and also helps control weeds (Balashev and Zeman, 1981).
• Improving heavy soils: If you have heavy clay soil that warms up slowly and is often waterlogged, be sure to add loosening materials: sand (1‑2 buckets per 1 m²), sawdust (pre‑rotted or treated with urea), shredded straw, or high‑moor peat.
• Raised beds: This is a real “lifeline” for regions with cold climates or heavy soils. Raised beds (20‑30 cm high) warm up faster in spring, drain excess water better, and roots develop more actively. Bed orientation – north to south (for maximum light) or considering prevailing winds (Gavrish, 2005).

3.4 Application of mineral fertilizers – precise calculation

Mineral fertilizers are “concentrates” of nutrition that are applied to correct specific deficiencies.

Phosphorus and potassium: These elements are immobile in the soil. Therefore, it is better to apply them in autumn or spring under digging so that they are evenly distributed in the root zone.

• Superphosphate (phosphorus): 50‑80 g/m².
• Potassium sulfate (potassium): 20‑30 g/m².
• Wood ash: An excellent source of potassium and micronutrients. Can be applied at 100‑200 g/m².

Nitrogen: Nitrogen is mobile and is quickly washed out of the soil by rain or irrigation. Therefore, it is applied mainly in spring and as top‑dressings during the growing season. In spring, you can apply ammonium nitrate (10‑15 g/m²) or urea (8‑10 g/m²).

Important: Excess nitrogen is as harmful as its deficiency. It provokes vigorous growth of tops at the expense of fruits, makes plants loose and more susceptible to diseases, and fruits watery and less sugary (Gavrish, 2005). Therefore, always follow recommended doses, especially for nitrogen fertilizers.

3.5 Mulching – a modern approach

Mulching is a mandatory agronomic practice in modern organic farming, especially relevant for open ground.

• Organic mulch (straw, hay, mown grass, peat, compost): This is the best way to retain moisture in the soil, prevent weed growth, and protect roots from overheating. A layer of mulch 5‑10 cm slows evaporation, maintains stable soil temperature, and, as it decomposes, serves as additional nutrition (Heuvelink et al., 2020). Apply mulch on moist soil after plants have grown and warmed up (for sunny regions, it can be done immediately after planting).
• Black plastic film (plastic mulching): Widely used in professional vegetable growing. It warms the soil well in spring, prevents moisture evaporation, and suppresses weeds (Santos and Salamé‑Donoso, 2018). Ideally suited for obtaining early harvests in regions with short summers. However, in hot climates, the soil under black film can overheat, so it is better to use film with a white (reflective) upper side or use organic mulch.

3.6 Step‑by‑step soil preparation plan

1. Autumn: Collect and remove plant residues (they can be a source of diseases). Apply organic matter (compost, well‑rotted manure) and phosphorus‑potassium fertilizers. Dig the bed to a spade depth.

2. Early spring (as soon as snow melts): If the bed has not yet been dug, do it now. Loosen the soil with a rake. If you plan raised beds, form them. Apply nitrogen fertilizers (if not applied in autumn). If beds were covered with black film, remove it so that the soil warms up faster.

3. 1‑2 weeks before planting: Thoroughly loosen the soil, remove weeds. Form the final configuration of beds and holes. Plan the planting scheme. If necessary, add additional compost or humus to the holes, thoroughly mixing with the soil.

4.1 Is seedling required?

In open ground, tomatoes can be grown both by seedling method and by direct sowing of seeds into the ground. However, for most temperate regions, seedling method is the only way to obtain a guaranteed harvest.

Why seedlings are better: Seedlings give the plant a “head start” of 50‑60 days. During this time, the plant manages to form a powerful root system and several flower clusters before being planted in open ground. This allows the tomato to yield a harvest before autumn cold and late blight. Direct sowing is justified only in southern regions with a long warm period, or for ultra‑early cultivars (e.g., 'Boni‑M', 'Betta') that can ripen in 80‑85 days (Gavrish, 2005). For beginner gardeners, I would recommend using seedlings – it is more reliable and simpler.

4.2 Timing of transplanting – the key question

Transplanting dates are determined not by calendar date, but by soil and air temperature. Tomato is a heat‑loving plant, and its roots begin to function normally only at soil temperatures above +14 °C (Gavrish, 2005; Jones, 2008). At lower temperatures, roots do not absorb nutrients, plant growth slows down, and it becomes susceptible to diseases.

• Key rule: Transplant seedlings when the threat of return frosts has passed and the soil at a depth of 10‑15 cm has warmed to +15…+16 °C. For most central regions, this is late May – early June.
• Folk wisdom guide: In central Russia, people often look at the flowering of bird cherry or lilac. When they begin to bloom, frosts are usually unlikely, but this is only an additional guide, not an exact science.

4.3 Age and quality of seedlings

Ideal seedlings for open ground should be:

• Age: 45‑60 days (from emergence).
• Height: 20‑30 cm, not leggy.
• Stem: Pencil‑thick (0.8‑1 cm), sturdy, with short internodes.
• Leaves: 7‑9 well‑developed, dark green leaves.
• Flower clusters: Preferably with the first flower cluster with buds (but not open flowers, to avoid stress during transplanting) (Gavrish, 2005).

4.4 Hardening off – preparation for life outdoors

Seedlings grown in greenhouse or home conditions are pampered. A sudden change of conditions (bright sun, wind, temperature fluctuations) can cause severe stress, up to leaf burn and death.

• Hardening process: Start hardening 7‑10 days before planting. If seedlings grew indoors, take them out to the balcony or greenhouse for a few hours, gradually increasing the time. If in a greenhouse, open the vents, and 3‑4 days before planting, leave the plants outdoors for 24 hours (Gavrish, 2005).
• Why it is needed: Hardening slows growth but increases cell resistance to adverse factors, increases the concentration of sugars in tissues, which acts as a kind of “antifreeze”. Hardened seedlings tolerate transplanting more easily and begin to fruit even earlier than unhardened ones planted at the same time.

4.5 Planting technique – doing it correctly

1. Preparing holes: A day before planting, prepare holes according to the chosen scheme. Hole depth – the size of the root ball. In each hole, you can add a handful of compost and ash, thoroughly mixing with the soil.

2. Time of planting: Plant seedlings on a cloudy day or in the evening when solar activity subsides. This will help plants cope more easily with transplant stress.

3. Planting methods:

• Vertical planting: Standard method for healthy, non‑overgrown seedlings. Place the root ball in the hole, fill with soil up to the root collar (the transition point from stem to root). Do not bury it!
• Slanted planting (for overgrown seedlings): If seedlings are leggy, they can be planted slanting, in a trench, placing the stem almost horizontally. The stem covered with soil will give additional adventitious roots, strengthening the root system. But do not bury the stem too deep if the soil is still cold – the upper layer warms up faster.
• Compaction and watering: After planting, lightly compact the soil around the roots to ensure good contact. Water each plant abundantly with warm water (1‑2 liters under the root). This removes air pockets from the soil and initiates the establishment process.

4.6 Protection from return cold – temporary covers

Even if you have waited for the “safe” date, the weather can surprise you with night cooling or frost. Young tomatoes are critically vulnerable to temperatures below +5 °C.

• Tunnel covers: The most reliable and simple solution for protecting young plants initially. Install arcs over the bed and cover them with non‑woven material (lutrasil, agril, spunbond) with a density of 30‑60 g/m² or film. This creates a greenhouse effect, protects from wind, and retains heat 2‑5 °C higher than outside (Gavrish, 2005). The cover can be left for a week or two until the plants take root and the weather becomes steadily warm.
• Individual caps: To protect individual plants, you can use cut plastic bottles, paper caps, or simply cover each bush with a bucket or cardboard box at night if a sharp cold snap is expected. Do not forget to remove the cover in the morning so that the plants do not overheat in the sun.
• When to remove the cover: As soon as the threat of frost has passed and steadily warm weather has established (average daily temperature above +15 °C), the covers can be removed. If you use cover to protect from wind and early frosts, it can be removed 1‑2 weeks after planting, leaving it in case of cold weather. Remember that in hot sunny weather under film, plants can overheat, so the film should be lifted for ventilation or removed in time.

5.1 Why is it so important?

• Stimulation of the root system: With deep and infrequent watering, moisture penetrates to a depth of 30‑40 cm, and roots are forced to grow deeper to reach water. This forms a powerful, deep root system that makes the plant more drought‑resistant and able to extract nutrients from deeper soil layers.
• Stability of soil moisture: Sharp fluctuations in moisture are the main cause of fruit cracking and blossom‑end rot. When after a long drought you give abundant watering, fruits quickly gain water, their skin does not keep up with pulp growth and bursts (Blancard, 2012). Constant, moderate moisture prevents this problem.
• Reducing disease risk: Watering in heat or after noon, especially by sprinkling, creates a film of water on leaves, which combined with high temperature becomes an excellent environment for the development of fungal diseases such as late blight and alternaria (Blancard, 2012).

5.2 How much and when to water?

The frequency and volume of watering depend on the plant development phase, air temperature, and rainfall.

• Active growth and flowering phase (before fruit set): During this period, the plant builds green mass. The soil should be moderately moist. Water plants only when the top layer of soil (5‑7 cm) dries out. Usually this is 1‑2 times a week, depending on weather. Watering rate – about 5‑10 liters per 1 m² (Heuvelink et al., 2020). Over‑watering is unacceptable, as it provokes the development of gray mold and other diseases.
• Fruit filling and ripening phase (from the formation of ovaries): This is the most critical period. The tomato's water requirement is maximal. Water plants 1‑2 times a week, but increase the rate to 15‑20 liters per 1 m² (Heuvelink et al., 2020). It is important to ensure deep wetting of the soil. In dry weather, watering can be increased to 2‑3 times a week, controlling soil moisture.
• 2‑3 weeks before the main harvest: To increase the sugar and dry matter content in fruits and accelerate their ripening, watering can be reduced or stopped altogether (Akhatov, 2010). This is especially relevant for tomatoes destined for processing or long‑term storage.

How to check if watering is needed? The simplest way is to take a handful of soil from a depth of 10‑15 cm. If it is dry and crumbles in your fingers – it is time to water. If it is moist and forms a ball – watering can be postponed.

5.3 How to water: rules and methods

Time of watering: Water early in the morning, before sunrise, or in the evening when the sun is not active. Morning watering is preferable, as leaves have time to dry before the heat sets in, which reduces the risk of fungal diseases. Evening watering (before 5‑6 pm) is also acceptable, but make sure leaves do not remain wet overnight.

Watering method: Water only at the root! Sprinkling (overhead watering) in open ground is categorically not recommended. Water on leaves and fruits in conditions of heat and high humidity is an invitation for diseases (Gavrish, 2005).

Drip irrigation: This is the ideal method for tomatoes. It provides:

• Uniform and economical moistening of the soil.
• Water delivery directly to the root zone.
• Possibility to combine watering with fertilizing (fertigation).
• Less weed growth.

Mulching: This is your best assistant in the fight for moisture. A layer of organic mulch (straw, hay, peat, compost) 5‑10 cm thick slows evaporation of moisture from the soil, prevents overheating of roots, suppresses weed growth, and serves as additional nutrition (Heuvelink et al., 2020). Mulch beds immediately after the soil warms up and warm weather sets in.

5.4 Watering after rain and in hot weather

Open ground is always working with the weather.

• After heavy rains: If heavy rain has passed, the next watering can be skipped. Check soil moisture. If it is heavily waterlogged, it is necessary to loosen the top layer to break the crust and provide air access to the roots. Nitrogen fertilizers applied superficially may be washed out, so they should be replenished through top‑dressing after the soil dries out a little.
• In hot and windy weather: Evaporation of moisture increases sharply. It may be necessary to increase watering frequency to 3‑4 times a week. In this case, you can reduce the volume of each watering (e.g., water 2 times a week with 20 l/m² or 3 times with 10‑12 l/m²). The main thing is not to allow prolonged drying of the soil during fruit filling.

5.5 Effect of watering on taste

Many gardeners notice that tomatoes grown in southern regions are sweeter. This is due not only to abundant sun but also to the fact that in hot climates watering is often limited. Moisture deficit during ripening forces the plant to concentrate sugars in the fruits (Blancard, 2012). Therefore, 2‑3 weeks before the main harvest, watering can and should be reduced – this will increase sweetness and improve fruit taste. However, do not overdo it! Complete cessation of watering during intense heat can lead to growth arrest and dropping of ovaries.

6.1 Main nutrients and their roles

To understand what and when to apply, let us briefly recall what each element is responsible for:

• Nitrogen (N): This is the “building material” for green mass. Responsible for stem and leaf growth. Deficiency: leaves pale, yellow, plant growth stops. Excess: plant “luxuriates” – produces vigorous foliage at the expense of fruits, fruiting is delayed, fruits become watery, plant becomes more susceptible to diseases (Gavrish, 2005; Jones, 2008). Open‑ground specificity: nitrogen is very mobile and easily washed out by rains. Therefore, it is applied in fractions throughout the season.
• Phosphorus (P): Responsible for root system development, flowering, and fruit set. Participates in sugar synthesis, improves fruit taste. Deficiency: leaves acquire a purple tint, stems thin, flowering and ripening delayed (Jones, 2008). Open‑ground specificity: phosphorus is immobile in soil; it is better to apply it in advance, under digging, or locally in holes.
• Potassium (K): The most important element for tomatoes during fruiting. Responsible for fruit filling, color, firmness, and shelf life. Increases resistance to diseases and drought. Deficiency: marginal leaf burn (chlorosis), fruits ripen unevenly, green patches appear (“green shoulders”) (Blancard, 2012; Heuvelink et al., 2020). Open‑ground specificity: potassium is also washed out, but slower than nitrogen. Its consumption increases sharply with the onset of fruiting.

6.2 How to adjust nutrition after rains

Precipitation is the main factor requiring correction of fertilisation in open ground.

Nitrogen leaching: Heavy rains can wash nitrate nitrogen (NO3) into deep soil layers, making it unavailable to roots. Symptoms: yellowing of lower leaves.

• What to do: If after prolonged rains you notice signs of nitrogen starvation, carry out foliar feeding with urea (1 tablespoon per 10 liters of water). This gives the plant quick access to nitrogen. Or root feeding with nettle infusion or cow manure (1:10) after the soil dries out a bit.

Potassium and magnesium leaching: Although potassium is less mobile than nitrogen, on light sandy soils it can also be washed out. Symptoms: marginal leaf chlorosis, fruits do not fill well.

• What to do: Apply potassium fertilizer (potassium sulfate – 1.5‑2 tablespoons per 10 liters of water) or wood ash (a glass per 10 liters of water, steep for a day). You can add magnesium sulfate (1 tablespoon per 10 liters of water), as magnesium is often washed out together with potassium.

Soil acidification: Frequent rains can acidify the soil, especially if it was initially close to neutral. When acidified, the availability of phosphorus, calcium, and magnesium decreases.

• What to do: If the soil is prone to acidification, together with potassium‑magnesium fertilisers, you can add dolomite flour (0.5‑1 glass per 1 m²), but do not overdo it so as not to make the soil alkaline.

6.3 Fertilisation schedule by growth phases

Here is an approximate fertilisation schedule for tomatoes in open ground. The number of feedings may vary depending on soil fertility and plant condition.

6.4 Foliar feedings: when and why

Foliar feeding (spraying on leaves) is first aid for plants. It is especially relevant in open ground when the root system for some reason does not work well (cold soil, waterlogging, overheating) or when a quick effect is needed.

When to use:

• After rains, to quickly replenish leached elements.
• In cold weather, when roots absorb nutrients poorly.
• During flowering – to improve fruit set (boron, zinc).
• During fruiting – to improve taste (potassium, magnesium).

How to use: Spray the underside of leaves (there are more stomata) in cloudy weather or in the evening. Make solutions weakly concentrated (as per instructions) to avoid burns.

6.5 Folk remedies for fertilisation

Many gardeners successfully use natural fertilisers that are no worse, and sometimes better, than chemical ones:

• Nettle infusion: An excellent nitrogen fertilizer and growth stimulant. Steep for 7‑10 days. Dilute 1:10.
• Ash: A treasure trove of potassium, calcium, magnesium, and micronutrients. Can be applied dry (into the soil) or as an infusion (a glass per 10 liters of water, steep for a day). An excellent alternative to potassium sulfate.
• Yeast: Stimulates root system growth and increases activity of soil microflora. Dissolve 100 g of raw yeast in 10 liters of warm water with sugar, leave for a few hours, dilute 1:5 and water at the root.

7.1 Why train the plant?

• Load regulation: Tomato has a powerful potential. If growth is not limited, it can form an endless number of shoots and flower clusters. But in open ground, the season is limited, and all these “extra” organs will only divert energy from already formed fruits, preventing them from ripening. Training helps balance vegetative (green mass growth) and generative (fruiting) development.
• Improving light and air penetration: A dense bush is an ideal environment for fungal diseases (late blight, gray mold) and pests. Training and removing excess leaves allow light and air to reach fruits and lower parts of the plant (Blancard, 2012).
• Accelerating ripening: By limiting the number of shoots and fruits, we help the plant concentrate all its strength on filling and ripening the remaining fruits. This is especially important in regions with short summers (Gavrish, 2005).

7.2 Tomato growth types and their training

Before training, it is important to know which type your cultivar or hybrid belongs to. This determines how exactly it should be trained.

• Indeterminate (tall): Grow without limit, constantly forming new flower clusters. In open ground, they are rarely grown, only in southern regions with a long season, or as a trellis crop on tall supports. They are trained strictly into one stem, removing all side shoots, and the tip is pinched 30‑40 days before the end of the season, leaving 2‑3 leaves above the top cluster to allow fruits to ripen (Balashev and Zeman, 1981).
• Semi‑determinate: Grow to 6‑8 clusters, then growth is limited. This is a good choice for open ground in warm climates. They can be trained into one or two stems.
• Determinate: Grow to 3‑5 clusters, then growth stops. These are the most common varieties for open ground. They are compact and can be grown without training. However, for early harvest they are also trained into 1, 2, or 3 stems (Gavrish, 2005).
• Super‑determinate (dwarf): The shortest and earliest. Quickly form 2‑3 clusters and stop growing. They practically do not require training. You can leave them without suckering, only remove lower aging leaves.

Plant training in open ground.

7.3 Training methods for open ground

For open ground, especially in temperate zones, the following schemes are most often used:

One stem (earliest harvest):

• For whom: For indeterminate and semi‑determinate varieties, and also for determinate if we want a very early harvest.
• How to do: Only one main stem is left on the plant. All side shoots (suckers) are removed regularly, not allowing them to grow more than 3‑5 cm. Leave 4‑5 lowest clusters (for determinate) and up to 8‑10 (for indeterminate, if season allows). Pinch the tip above the top cluster one month before the expected end of the season.
• Pros: Early fruit ripening, fruits larger.
• Cons: Fewer fruits per plant.

Two stems (optimal balance):

• For whom: For determinate and semi‑determinate varieties. This is the most popular method for open ground.
• How to do: Leave the main stem and one sucker. The strongest sucker is usually left from the leaf axil below the first flower cluster (Gavrish, 2005). Remove all other suckers. Leave 3‑4 clusters on each stem.
• Pros: Good balance between yield and ripening time. Fruits are large enough and ripen uniformly.

Three stems (maximum yield):

• For whom: For determinate varieties, especially in southern regions or with good agronomy.
• How to do: Leave the main stem and two strongest suckers: one below the first cluster, the second below the second (or 2‑3 leaves from the first). Remove all other suckers. Leave 2‑3 clusters on each stem. This gives the highest total yield, but fruits will ripen later and may be smaller.
• Pros: Highest overall yield.
• Cons: Later ripening, may require more space and supports.

7.4 Main operations in training

1. Suckering (removing side shoots):

• What it is: Removing shoots that grow from leaf axils (the angle between leaf and stem).
• When: Suckers are removed regularly, once every 5‑7 days, not allowing them to overgrow. It is best to remove them when they reach 3‑5 cm in length. At this time, the operation is least painful for the plant.
• How: Snap out suckers with your fingers (pinch), leaving a small stump (0.5‑1 cm) so that a new shoot does not appear in that place. If the sucker has already grown, it is better to remove it with pruning shears to avoid injuring the stem. It is advisable to perform this operation in dry, sunny weather so that wounds heal faster (Blancard, 2012; Gavrish, 2005).

2. Tip pinching (topping):

• What it is: Removing the growing point on the main stem and suckers.
• Why: Stops stem growth, directing all nutrients to already formed fruits. This is critically important for obtaining a harvest in regions with short summers.
• When: Usually 30‑40 days before the expected end of the season (harvest). By this time, the plant should already have enough fruits that will have time to ripen.
• How: Carefully remove the tip of the stem, leaving 2‑3 leaves above the last flower cluster. These leaves will provide nutrition to fruits on that cluster (Gavrish, 2005).

3. Fruit thinning:

• What it is: Removing excess flowers and ovaries in a cluster.
• Why: Used to obtain very large fruits. If only 1‑2 ovaries are left in a cluster, they will grow much larger.
• How: When fruits set, leave the largest ones and remove the rest. In practice, flowers at the top of the inflorescence are often removed, leaving 4‑6 of the most vigorous ovaries in the cluster.

4. Removal of lower leaves:

• Why: Improves air circulation in the lower part of the bush, reducing the risk of late blight and other fungal diseases. It also promotes faster fruit ripening.
• When: Gradually, as fruits on lower clusters ripen, remove leaves below them.
• How: Remove old, yellowed, or diseased leaves. It is important not to remove all leaves at once – this weakens the plant. Usually 1‑2 leaves per week are removed under each ripening cluster. Never remove leaves above unripe fruits (Gavrish, 2005).

7.5 Practical recommendations for open ground

• For determinate varieties: In open ground, we do not aim to get many clusters. Usually 4‑5 clusters on 1‑2 stems are left. For early harvest – train into 1 stem and leave 3‑4 clusters, pinching the tip. For maximum yield – train into 2 or 3 stems, leaving 3 clusters on each. Important: if you train the plant into 1 stem and leave few clusters, it can be planted more densely (Gavrish, 2005).
• For dwarf and super‑determinate varieties: They practically do not require training. You can only remove lower leaves as fruits ripen and upper suckers if they grow too vigorously. In the case of varieties like 'Boni‑M' or 'Betta', suckering can be omitted altogether.
• Considering climate: In cold and humid regions, prefer training into 1 stem. This ensures better ventilation and accelerates ripening. In warm and dry regions, you can train into 2‑3 stems.

8.1 Heat (temperature above +30…+35 °C)

High temperature is one of the most serious stresses for tomatoes. It negatively affects all life processes of the plant.

Problems:

• Pollen sterility: At temperatures above +30 °C during the day and above +20 °C at night, pollen becomes sterile, fruits do not set (Sato et al., 2006 in Heuvelink et al., 2020; Gavrish, 2005). This leads to flower drop and hollow fruits (“puffy”).
• Stoppage of photosynthesis: At temperatures above +35 °C, photosynthesis practically stops, the plant switches to survival mode.
• Sunburn: Direct sunlight combined with high temperature can burn fruits and leaves, especially if the plant is poorly foliated (Blancard, 2012). On fruits, pale, watery spots appear, which then dry out and become hard.

How to protect:

• Shading: During the hottest hours (11 a.m. to 4 p.m.), shade the plants. You can use light shade nets, non‑woven material (spunbond, agril), or even old sheets draped over arcs or stakes. In greenhouses, whitewashing the roof or interior screens are used (Akhatov, 2010). In open ground, tall curtain plants work well.
• Watering: In heat, watering should be abundant and regular. Water early in the morning or evening so that water does not evaporate instantly. A good layer of mulch (straw, hay) protects roots from overheating and retains moisture.
• Anti‑stress treatments: In extreme heat, you can carry out foliar feeding with drugs that increase stress resistance (e.g., humates, succinic acid, or anti‑stress preparations like "Megafol") (Akhatov, 2010).
• Cultivar choice: Prefer heat‑tolerant varieties and hybrids that set fruit better in hot conditions (e.g., hybrids with genetic resistance to high temperatures, such as 'Biatlon', 'Tamerlan').

8.2 Hail

Hail is mechanical damage to tissues. It can pierce leaves, stems, and, worst of all, damage fruits, making them unsuitable for sale and storage (Akhatov, 2010).

How to protect:

• Cover: The most reliable way is to cover plantings with durable non‑woven material or fine‑mesh netting when hail is threatened. You can use arcs and film, but film can be torn by hail.
• Protective screens: Large farms use special anti‑hail nets. For amateur gardeners, this is an expensive pleasure, so often improvised means are used: old curtains, dense fabric.
• Important: After hail, treat plants with copper‑containing preparations (e.g., Bordeaux mixture or copper oxychloride) to prevent infection through damaged tissues (Blancard, 2012).

8.3 Strong wind

Wind dries out the soil, increases evaporation from leaves, can break stems and flower stalks, and also contributes to the spread of diseases and pests.

How to protect:

• Windbreak strips (curtains): Plant tall plants (corn, sunflower) on the windward side to serve as natural barriers.
• Fences and shields: If the site is not protected, you can install temporary shields from boards, plywood, or dense fabric.
• Staking: Be sure to tie plants to sturdy supports (stakes, trellis). This protects them from lodging and stem breakage.
• Cover: In strong winds, you can temporarily cover plants with non‑woven material, which reduces wind speed.

8.4 Downpours and prolonged rains

Excess moisture in open ground is a serious problem, especially during fruit filling.

Problems:

• Fruit cracking: A sharp transition from drought to abundant watering (rain) causes fruits to split (Blancard, 2012).
• Development of fungal diseases: High humidity and wet leaves are an ideal environment for late blight, alternaria, and brown spot.
• Leaching of fertilizers: Rain washes out nitrogen, potassium, and magnesium from the soil.

How to protect:

• Good drainage: Plant tomatoes on raised beds or ensure good drainage away from roots.
• Mulching: A layer of mulch protects the soil from erosion, but during heavy rains it can become too wet.
• Rain cover: In regions with frequent rains, you can use temporary film covers or tunnels that protect plants from direct precipitation. In greenhouses, ventilation systems are used for this (Akhatov, 2010). Important: after rain, ensure good ventilation so that leaves dry quickly.
• Nutrition correction: After prolonged rains, carry out foliar feedings to replenish leached elements (nitrogen, potassium, magnesium).
• Disease treatment: After rain, be sure to carry out preventive treatment with copper‑containing preparations (Bordeaux mixture, copper oxychloride) or bio‑preparations (e.g., "Fitosporin") to prevent the development of fungal infections (Blancard, 2012; Gavrish, 2005).

8.5 Cold nights and return frosts

Even after transplanting seedlings, cold snaps and frosts are possible that can destroy young plants.

Problems:

• Growth arrest: At temperatures below +12 °C, tomato growth stops (Heuvelink et al., 2020).
• Damage to flowers: Frosts below 0 °C kill flowers and ovaries. At ‑2 °C, the plant dies (Jones, 2008).

How to protect:

• Temporary covers: The most reliable way is to use arcs with film or non‑woven material (lutrasil, spunbond). The cover retains heat, protects from wind, and from frosts down to ‑3…‑5 °C (Akhatov, 2010). You can also use individual caps from cut plastic bottles or paper.
• Smudging: An old method of frost protection is to light smoky piles on the site. Smoke creates a screen that retains heat (Akhatov, 2010). Nowadays this is rarely used, but in extreme cases you can light a fire with wet wood.
• Watering: Before frost, abundant watering can help, as wet soil cools more slowly, but this method is not always effective.
• Hardening: Hardened seedlings are significantly more resistant to short‑term cold snaps than pampered ones (Gavrish, 2005).

8.6 Summary: action plan for extreme weather

9.1 Why are diseases and pests especially dangerous in open ground?

• Natural background: Spores of fungi and bacteria are constantly present in the soil and air.
• Weather factors: Rain, dew, wind, and temperature fluctuations create ideal conditions for the development of many diseases (Blancard, 2012).
• Contact with soil: Leaves and fruits touching the ground are easily infected by soil pathogens.
• Spread: Wind and insects quickly spread infection throughout the plot.

9.2 Main diseases of tomatoes in open ground

9.3 Main pests of tomatoes in open ground

9.4 Principles of integrated protection

Instead of fighting the consequences, it is better to prevent problems. Integrated Pest Management (IPM) is a comprehensive approach that includes:

1. Preventive measures:

• Use of healthy seed material and resistant varieties.
• Observing crop rotation.
• Balanced nutrition (do not overfeed with nitrogen!).
• Optimal watering (do not overwater!).
• Regular removal of weeds and plant residues.
• Soil mulching.
• Regular inspection of plants.

2. Biological methods:

• Attracting beneficial insects (entomophages).
• Use of bio‑preparations (Fitosporin, Trichoderma, Bitoxibacillin) (Gavrish, 2005).

3. Chemical methods (as a last resort):

• Use of pesticides only when economic threshold of harmfulness is reached.
• Rotation of preparations with different modes of action to avoid resistance.
• Strict adherence to application instructions, dosages, and waiting periods.
• Treatment in windless, dry weather, in the morning or evening.

9.5 Practical protection checklist

10.1 Stages of fruit ripeness

Tomatoes can be harvested at different stages of ripeness, depending on your goals: immediate consumption, transport, or storage. Usually, several stages are distinguished (Jones, 2008; Heuvelink et al., 2020):

• Green stage (technical maturity): Fruits have reached full size, but are still completely green. On cut, seeds are already formed and covered with a dense shell. Harvested at this stage, they are capable of ripening during storage. Used for long‑distance transport and storage.
• Breaker stage (milk ripeness): Fruits begin to lighten, a pinkish or yellowish tint appears. The flesh inside becomes pink. This is the ideal stage for ripening at home. Fruits keep well and transport well.
• Pink (brown) stage: Fruits are 30‑60% colored. They already have good taste, but are not yet sweet and aromatic enough. At this stage, they are harvested for sale in local markets or for ripening.
• Red (full) stage (biological maturity): Fruits are fully colored in the characteristic color of the variety (red, pink, yellow, orange). They contain the maximum amount of sugars, vitamins, and aromatic substances. Fruits at this stage have the richest flavor, but they are not suitable for long‑term storage and transport. They are harvested for immediate consumption or processing.
• Overripe stage: Fruits become too soft, lose firmness and taste. They may crack and rot. Harvesting at this stage is undesirable.

10.2 When and how to harvest?

Regularity of harvest: Harvest fruits regularly, at least 1‑2 times a week, and during mass fruiting – every 3‑4 days. Regular harvesting stimulates the plant to form new ovaries, and also prevents over‑ripening of fruits on the bush and spread of diseases. If you leave overripe fruits on the bush, they will take nutrients from new ovaries and can become a source of infection (Balashev and Zeman, 1981; Gavrish, 2005).

Time of harvest: Harvest fruits in dry, sunny weather, in the morning after dew has dried, or in the evening when the heat subsides. At this time, fruits are most elastic and less damaged during harvesting and transport. Do not harvest fruits in the rain or immediately after – they will be wet and spoil faster.

Method of harvesting: Fruits should be harvested with the pedicel, carefully breaking it off from the stem, or cutting with pruning shears. Leave the pedicel 1‑2 cm long. This prevents damage to the skin and reduces the risk of infection. Do not pull the pedicel out of the fruit – this injures the fruit, worsens its keeping quality, and can lead to rotting. When harvesting, do not squeeze or crush fruits, as this causes dents and rapid spoilage.

Sorting at harvest: Immediately at harvest, sort fruits by ripeness stage and purpose:

• For immediate consumption: Select the ripest, brightly colored fruits.
• For ripening and storage: Select fruits at breaker or pink stage, without damage.
• For processing (canning, juices, sauces): You can use fruits of different ripeness stages, including ripe and breaker.
• Culling: Separately collect and destroy damaged, cracked, or diseased fruits so that they do not become a source of infection for healthy fruits.

10.3 Ripening and storage of fruits

One of the valuable qualities of tomatoes is their ability to ripen after harvest. This allows you to extend the period of consumption of fresh fruits.

Why it is needed: In regions with short summers, not all fruits have time to ripen on the bush before frost. Ripening allows you to obtain a full harvest even in such conditions. Also, ripening is convenient for regulating the supply of fruits to the table: you can pick a batch of breaker fruits and ripen them as needed.

Conditions for ripening:

• Temperature: Optimal temperature for ripening is +20…+25 °C. At this temperature, fruits ripen quickly (5‑8 days). At lower temperatures (+12…+15 °C), the process slows down, and below +10 °C fruits stop ripening (Gavrish, 2005).
• Humidity: Optimal air humidity is 80‑85%. Higher humidity promotes rotting, lower – fruits wither.
• Light: Light is not needed for ripening, but some gardeners note that in light, fruits acquire a brighter color. Important: direct sunlight during ripening is not needed, as it can dry out fruits.
• Ethylene: Ripening accelerates in the presence of ethylene – a gas released by ripe fruits. Therefore, to speed up ripening, you can put one ripe apple or banana with green fruits.

Methods of ripening:

• In boxes or baskets: Place fruits in 2‑3 layers in boxes or baskets, interlayering them with dry sawdust, shavings, or paper so that they do not touch each other. Periodically sort, removing rotten ones.
• In closed plastic bags: Bags create increased humidity and ethylene concentration, which accelerates ripening, but increases the risk of rotting. Use bags with ventilation holes.
• On the bush in hanging position: In autumn before frost, you can pull up plants with roots and hang them upside down in a dry, ventilated room. Nutrients from the stem and leaves will continue to flow into the fruits. This method yields tastier fruits but requires more space.

Storage conditions:

• For ripe fruits: Store at +4…+6 °C and air humidity 80‑90%. Under such conditions, ripe fruits can be stored for 2‑4 weeks.
• For breaker and pink fruits: Optimal storage temperature is +8…+12 °C. At lower temperatures, they stop ripening and lose taste. Storage period can be 1‑2 months.
• For green fruits (ripening): Store at +12…+15 °C. Under such conditions, green fruits can be stored for 2‑3 months, gradually ripening.

10.4 How to extend fruiting in autumn

To extend the harvest and get more ripe fruits, use several techniques:

• Tip pinching: 30‑40 days before expected frosts, pinch the tips of all shoots. This stops growth and directs all nutrients to already formed fruits.
• Removing flowers: Remove all flowers appearing at this time – they still will not have time to produce fruits, but will take energy from ripening ones.
• Removing excess leaves: Gradually remove lower leaves, exposing stems. This improves ventilation and accelerates fruit ripening.
• Cover from frosts: If frosts are forecast, cover plants with film or non‑woven material overnight. This can extend the growing season by several weeks.
• Harvest all fruits before frost: If frost is inevitable, harvest all fruits, even green ones. They will ripen indoors.

11.1 Work calendar by tomato growth phases

11.2 Work calendar by weather conditions and soil status

11.3 Practical advice: keep a diary

To make your calendar as effective as possible, keep a field diary. Write down:

• Weather conditions: Temperature, precipitation, wind.
• Plant growth phases: Dates of flowering, fruit set, start of ripening.
• Work carried out: Dates of watering, fertilisation, treatments, suckering.
• Observations: Which varieties performed best, what problems arose.

By comparing records from different years, you will be able to better plan your actions and adapt agronomic practices to the specifics of your plot. This is the path to stable and high yields.