Soil Preparation

Loose, “Breathable” Structure

Although the tomato root system has a deep taproot, 70 % of it consists of thin, actively absorbing roots in the top 20‑cm layer (Autko et al., 2012). For their normal functioning, two conditions are critical: aeration (oxygen access) and the absence of physical barriers.

Why it matters: Tomato roots are very sensitive to oxygen deficiency (Autko et al., 2012). In dense, slaking soil or under overwatering, they suffocate, stop absorbing nutrients (especially phosphorus and potassium), and become easy prey for pathogens.

Practical takeaway: The soil should be cloddy, not dusty, and not clumping into a monolithic mass. Deep digging (to a spade’s depth) with mandatory loosening, as well as avoiding work on wet soil, are basic rules.

Optimal Acidity (pH) – The “Golden Mean”

Tomatoes are not extremists. They prefer a neutral or slightly acidic soil solution reaction. This is not a whim but a matter of nutrient availability.

Ideal range: pH 6.0–6.5 (Jones, 2008; Hochmuth and Sideman, 2023).

Why this works: In this narrow corridor, all major nutrients (nitrogen, phosphorus, potassium, calcium, magnesium) and micronutrients (iron, boron, manganese, zinc) are in their most plant‑available forms. Deviations lead to deficiencies. For example, at pH above 6.8, the availability of iron and boron drops sharply, causing chlorosis of young leaves and blossom‑end rot of fruits (Jones, 2008). On acid soils (pH < 5.5), plants suffer from aluminium and manganese toxicity, and phosphorus is bound into unavailable compounds (Hochmuth and Sideman, 2023).

Practical takeaway: Do not guess. You can determine soil pH using a simple test‑strip kit or a portable pH meter. This will give a clear understanding of whether liming (to raise pH) or sulfur addition (to lower pH) is needed.

Moderate but Balanced Nutrition

Tomato is a “hungry” plant, but an excess of fertiliser, especially nitrogen, harms it more than a deficiency.

Nitrogen (N): Essential for vegetative growth. However, excess nitrogen causes “luxuriant growth” – lush foliage at the expense of flowering and fruit set, and also reduces disease resistance (Jones, 2008; Gould, 1992). The dose should be moderate.

Phosphorus (P): A key element for the development of a strong root system and the formation of flower trusses. Its deficiency sharply retards growth and delays ripening (Swiader and Ware, 1992).

Potassium (K): The most important element for fruit quality. It is responsible for sugar content, firmness, storage ability, and disease resistance (Atherton and Rudich, 1986). The tomato’s need for potassium is higher than for nitrogen, especially during fruiting (Jones, 2008).

Organic Matter – Not Just Food, but a Habitat

Organic matter (humus, compost, rotted manure) performs three critical functions in the soil:

1. Improves structure: It binds sandy particles, giving them the ability to retain moisture and nutrients, and loosens clayey soils, making them more air‑permeable.

2. Is a nutrient source: During mineralisation, organic matter slowly releases nitrogen, phosphorus, potassium, and micronutrients.

3. Supports biological activity: The activity of soil bacteria and fungi that process organic matter is directly linked to the availability of nutrients for plants.

Important caveat: Fresh manure is not the tomato’s best friend. Applying it just before planting can burn roots, and the excess of readily available nitrogen can provoke luxurious growth. Use only well‑rotted manure or compost (Jones, 2008). It is best applied in autumn under digging.

Drainage – The Key to Root Health

Tomato is not rice. Water stagnation at the roots is detrimental. It leads to oxygen starvation, and the development of late blight and fusarium wilt.

Sign of a problem: If after rain or watering water stands in puddles on your plot for more than 2–3 hours, this is a signal that drainage needs improvement, for example, by constructing raised beds (ridges) or adding loosening materials (sand, compost).

Thus, the ideal soil for tomatoes is loose, well‑drained loam or sandy loam, with pH 6.0–6.5, rich in well‑rotted organic matter, and containing a balanced reserve of major nutrients. By understanding these requirements, you can purposefully prepare your plot rather than acting at random.

Question 1. Does water stand for a long time after rain or watering?

• Yes, water does not drain for 2–3 hours or longer.
• is is a clear sign of poor drainage. Most likely, you have dense clay soil or a compacted layer (plough pan) at a depth of 20–30 cm. Tomatoes cannot tolerate waterlogging – roots suffocate, leading to growth inhibition and outbreaks of root rots (Jones, 2008).
• No, water soaks in almost immediately.
• is means drainage is good. The soil is either sandy or well‑structured. This is a plus, but remember: on such soils, nutrients and moisture leach faster, and fertilising will be needed more often (Hochmuth and Sideman, 2023).

Question 2. Does a wet clod of soil stick together into a dense, plasticine‑like mass?

• Yes, the clod does not crumble, stains hands, and does not break even with light pressure.
• is is heavy loam or clay. Such soil is rich in nutrients but poorly permeable to air and warms up slowly in spring. Tomato roots have difficulty breathing in it and often suffer from excess moisture (Autko et al., 2012).
• No, the clod is loose and falls apart easily.
• u have good structure. If the soil does not turn to dust, it is ideal.

Question 3. Is there a white or greyish coating on the soil surface?

• Yes, especially in dry weather.
• is is salt efflorescence. Often occurs when watering with hard water or overdosing mineral fertilisers. Tomatoes are sensitive to salinity – their roots absorb water less effectively, and fruits suffer from blossom‑end rot (Atherton and Rudich, 1986; Hochmuth and Sideman, 2023).
• No, the surface is clean. – Salinisation is unlikely.

Question 4. Are there many horsetail (field horsetail), buttercup, plantain, or moss on the plot?

• Yes, these plants dominate the grass cover.
• ey are natural indicators of acidic soil. On acidic soils (pH < 5.5), tomatoes poorly absorb phosphorus, calcium, magnesium and suffer from toxic aluminium (Swiader and Ware, 1992; Jones, 2008).
• There are few or no such plants. – The pH is probably closer to neutral, but this does not negate the need for an accurate test.

Question 5. Does the soil dry out quickly and crack like a desert?

• Yes, a day or two after watering, the crust cracks.
• is is a sign of sandy soil with low organic matter content. Moisture escapes instantly, and with it nutrients. Tomatoes on such soil constantly struggle with drought and starvation (Hochmuth and Sideman, 2023).
• No, the soil retains moisture for several days. – Structure and water‑holding capacity are fine.

Question 6. Is there a smell of rot or swamp, especially in wet weather?

• Yes, there is an unpleasant putrid smell.
• is is a signal of anaerobic processes – there is a lack of oxygen in the soil, organic matter is rotting rather than decomposing into nutrients. Such soil is a breeding ground for pathogens. Tomatoes will suffer here (Jones, 2008).
• No, the smell is earthy, fresh. – Everything is fine.

Question 7. How does the soil behave in a simple acidity test?

Take two small soil samples from different places (from a depth of 10–15 cm). Moisten them with distilled water. Drop table vinegar on one and baking soda solution on the other.

• Fizzes on vinegar – alkaline soil (pH > 7.5). This is rare, but requires lowering pH by adding sulfur.
• Fizzes on soda – acidic soil (pH < 5.5). Liming is required.
• No fizzing on either – pH is somewhere in the middle, but the exact value will only be shown by a device or litmus paper (Hochmuth and Sideman, 2023).

What Next?

You already have a preliminary diagnosis. Even if not all answers matched the “ideal”, do not despair. Knowing the problems, you can correct them. For example:

• Poor drainage → make raised beds.
• Clayey structure → add coarse sand and organic matter.
• Acidic soil → lime.
• Sandy soil → increase organic matter and use mulch.

The main thing is not to act at random. The next chapter will tell you how to correct the identified shortcomings.

Problem 1. Water stands after rain (poor drainage)

Tomato roots suffocate without oxygen access (Jones, 2008). Water stagnation is a direct path to late blight, fusarium wilt, and growth inhibition.

How to fix:

• Make raised beds (ridges). Raise plantings 20–30 cm above the general soil level. This is a classic technique for regions with excessive moisture (Gould, 1992; Autko et al., 2012). Moisture drains into the rows, while roots remain in an aerated layer.
• Add loosening materials. Clay soils are improved by adding coarse river sand (not construction sand!) and well‑rotted organic matter (compost, manure). Sand creates pores, organic matter binds clay particles into loose clods (Hochmuth and Sideman, 2023).
• Deep loosening. If there is a dense “plough pan” under the top fertile layer, break it up with a deep ripper (manual or mechanical) to a depth of 40–50 cm. This will improve drainage and allow roots to penetrate deeper (Welbaum, 2015).

Problem 2. Soil is sticky like plasticine (heavy loam or clay)

Plants have difficulty penetrating, roots experience mechanical resistance, and the soil warms up slowly in spring (Autko et al., 2012).

How to fix:

• Add organic matter. This is the main remedy. Add 10–15 kg of well‑rotted manure or compost per 1 m² under digging. Organic matter causes clay particles to aggregate – forming water‑stable clods, improving aeration and water permeability (Hochmuth and Sideman, 2023; Jones, 2008).
• Green manures with powerful root systems. Sow rye, oats, or mustard in autumn. Their roots break up clay clods, and spring incorporation of green mass enriches the soil with organic matter (Kemble et al., 2022).
• Do not work with wet soil. Digging or cultivating wet clay turns it into concrete. Wait until the soil dries to a “crumbly in hand” state (Swiader and Ware, 1992).
• Add sand or vermiculite. Adding 10–20 kg/m² of coarse sand improves structure, but on its own with clay it does not always work – better in combination with organic matter (Hochmuth and Sideman, 2023).

Problem 3. White coating on the surface (salinisation)

Excess salts prevent roots from absorbing water. Tomatoes suffer from thirst even in moist soil (Atherton and Rudich, 1986).

How to fix:

• Leaching. In autumn or early spring, water the plot with clean water at the rate of 10–15 l per 1 m² to wash excess salts into lower horizons. Repeat 2–3 times with intervals of several days (Hochmuth and Sideman, 2023).
• Stop using hard water. For irrigation, use settled rainwater or well water with low mineralisation. If impossible, apply mineral fertilisers with a high salt index less frequently (Swiader and Ware, 1992).
• Add organic matter. It binds excess salts and improves structure, facilitating their leaching (Hochmuth and Sideman, 2023).
• Do not over‑fertilise. Excess fertiliser is the main cause of salinisation. Stick to moderate recommended doses.

Problem 4. Many horsetails, buttercups, moss (acidic soil)

In an acidic environment (pH < 5.5), phosphorus, calcium, and magnesium become unavailable, while aluminium and manganese become toxic to tomatoes (Jones, 2008).

How to fix:

• Liming. In autumn, apply dolomite lime (which contains calcium and magnesium) or slaked lime. The rate depends on acidity (determine by test), usually from 200 to 500 g per 1 m² for sandy soils and up to 800 g for clay soils (Hochmuth and Sideman, 2023). Lime should be applied 2–3 months before planting, preferably under autumn digging.
• Repeat liming every 3–4 years. Acidity recovers over time (Swiader and Ware, 1992).
• Use wood ash. It alkalises the soil, but acts more gently and faster than lime. Apply 1–2 cups per 1 m² in spring or autumn (Welbaum, 2015).
• Do not plant on acidic soils without prior preparation. If time is lost, add dolomite to the planting holes (1–2 tablespoons each) – this will locally reduce acidity for the young plant (Heuvelink, 2018).

Problem 5. Soil dries quickly and cracks (sandy)

Water and nutrients leach deep like through a sieve. Tomatoes suffer from drought and starvation (Hochmuth and Sideman, 2023).

How to fix:

• Add plenty of organic matter. This is the only way to increase the water‑holding capacity of sand. Add 20–30 kg/m² of compost or well‑rotted manure under digging (Jones, 2008). Organic matter acts like a sponge, retaining moisture.
• Use mulching. A layer of mulch (straw, mown grass, compost, black film) 5–10 cm thick sharply reduces evaporation and retains moisture near the roots (Gould, 1992; Kemble et al., 2022).
• Add clay or bentonite (in small amounts). This improves moisture retention, but requires care (better consult an agronomist).
• Water more often, but in small doses. Sandy soil does not hold moisture, so watering is needed every 2–3 days, especially in hot weather (Swiader and Ware, 1992).
• Increase the dose of potassium fertilisers. Potassium improves the water‑holding capacity of tissues, increasing drought tolerance (Atherton and Rudich, 1986).

Problem 6. Smell of rot (anaerobic processes)

This is a signal that pathogenic bacteria and fungi have appeared in the soil, and organic matter is not decomposing but rotting (Jones, 2008).

How to fix:

• Provide drainage (see Problem 1). The main cause is excess moisture and lack of oxygen.
• Add fresh organic matter (compost, peat). It loosens the soil and “starts” aerobic processes (Hochmuth and Sideman, 2023).
• Do not use fresh manure. It will only increase rotting. Only well‑rotted.
• Dig the plot to a full spade depth. This aerates the top layer and destroys anaerobic zones.
• Use Trichoderma or other biological products. They help suppress pathogenic microflora and restore a beneficial community of soil organisms (Welbaum, 2015).

Important Addition

Most problems are corrected not by one but by a combination of measures. For example, on heavy clay, you simultaneously add organic matter, sand, and make raised beds. On sand – organic matter and mulch. Improving soil structure is a gradual but rewarding process. Within a year, you will notice that the soil becomes softer and more alive, and tomatoes respond with an abundant harvest. The main thing is not to rush and not to overdo chemistry: more is not always better.

Organic Matter: The Basis of Fertility

Organic substances (compost, humus, green manures) are not just nutrition, but a “revitaliser” of soil life. They improve structure, retain moisture, feed microorganisms, and gradually release elements in available form.

Mineral Fertilisers: The Three Pillars

Mineral elements are divided into macro (nitrogen, phosphorus, potassium) and micro (boron, iron, manganese, etc.). For tomatoes, three macronutrients are critically important, but their ratio must be balanced.

Micronutrients: Small but Vital

Tomatoes need small amounts of boron, iron, manganese, zinc, copper, molybdenum. Their deficiency often appears on acidic or over‑limed soils.

• Boron (B) – critical for flowering and fruit set. Deficiency causes blossom‑end rot and fruit cracking. Apply 1–2 g of boric acid per 10 l of water for spraying at budding stage (Jones, 2008).
• Iron (Fe) – deficiency causes young leaves to yellow (chlorosis). Chelated forms (e.g., Ferrovit) applied foliarly are best (Welbaum, 2015).

Important: Excess micronutrients (especially boron and manganese) is toxic. Apply only as needed and strictly according to instructions.

What Is Better Not to Apply

1. Fresh manure – see above.

2. Potassium chloride – chlorine inhibits tomatoes. Use sulfate forms.

3. Excess nitrogen – do not exceed recommended doses, especially during fruiting.

4. Single‑nutrient fertilisers without considering pH – if the soil is acidic, phosphorus and potassium will be unavailable no matter how much you apply (Swiader and Ware, 1992).

5. Undecomposed plant residues (straw, fresh grass) – they “tie up” nitrogen during decomposition, causing nitrogen starvation in tomatoes.

Quick Reference for Application

• Autumn: dolomite lime (if pH < 6.0) + phosphorus fertilisers (superphosphate) + compost/humus (10–20 kg/m²).
• Spring (2–3 weeks before planting): digging + potassium fertilisers (potassium sulfate) + additional compost (if not applied in autumn).
• In the hole: a handful of vermicompost or humus + 10 g of superphosphate.
• Top dressings (during growth): ammonium nitrate (10–15 g/m²) 2–3 weeks after transplanting, then potassium top dressing at the beginning of flowering and fruiting (potassium sulfate 15–20 g/m²).
• Foliar: boron‑ or iron‑containing preparations at the first signs of deficiency.

Now that you have a clear picture of what and when to apply, let us move on to the next stage – step‑by‑step preparation of the tomato bed.

Step 1. Choose the Time

It is best to start soil preparation in autumn, after harvesting previous crops (Swiader and Ware, 1992). This gives time for the main amendments (lime, organic matter, phosphorus) to gradually interact with the soil. In spring, only final finishing remains.

If you did not manage in autumn, you can prepare the plot in spring, but at least 3–4 weeks before transplanting (Jones, 2008). In that case, use fast‑decomposing organic fertilisers (compost, vermicompost) and avoid fresh manure.

Step 2. Clear the Plot

Remove all plant residues (tops, weeds, roots). It is better not to bury them but to send them to compost or burn (if there were diseases) to avoid provoking pathogens (Gould, 1992).

Step 3. Conduct Final Diagnostics (if not done)

If you have not yet performed tests, do it now:

• pH test – with litmus paper or a portable pH meter (Hochmuth and Sideman, 2023).
• Structure test – take a wet clod and squeeze it. If it does not crumble, the soil is heavy; if it crumbles to dust, it is light sandy.

Based on this data, you decide which adjustments are needed (see Chapters 3 and 4).

Step 4. Adjust Acidity (if necessary)

If pH < 6.0 (acidic soil), apply dolomite lime (contains calcium and magnesium) or slaked lime. Rate: for sandy soils _{200–300 g/m², for clay soils} 400–600 g/m² to raise pH by 0.5–1 unit (Hochmuth and Sideman, 2023). Apply in autumn under digging so that the reaction stabilises by spring.

If pH > 7.0 (alkaline), you can use elemental sulfur (30–50 g/m²) to lower it, but this is a slow process, and you may not have time in spring. In that case, focus on organic mulches and acidifying watering (water with citric acid) (Swiader and Ware, 1992).

Step 5. Apply Organic Matter and Basic Fertilisers

This is the key step.

Step 6. Form the Beds

Tomatoes grow better on raised beds (ridges) 20–30 cm high and 60–80 cm wide. This provides drainage, rapid warming, and air access to the roots (Gould, 1992; Autko et al., 2012). Make rows at least 70–80 cm apart for ease of care and ventilation.

• For open ground – ridges are best oriented north‑south for even sunlight.
• For a greenhouse – you can make flat raised beds bordered by sides, or use containers (Heuvelink, 2018).

If the plot is level and does not suffer from waterlogging, flat beds are acceptable, but then mulching is mandatory.

Step 7. Loosen and Level the Surface

A day or two before planting, go over with a rake or cultivator to break the crust and level the surface. This will allow even moisture distribution during watering and facilitate planting.

If the soil has become heavily compacted after digging, you can additionally loosen the top layer by 5–10 cm without turning the soil (Welbaum, 2015).

Step 8. Disinfect (if necessary)

If there were diseases in the past season (late blight, fusarium, root rots), it is worth carrying out biological disinfection: water the soil with a solution of Trichoderma or another biofungicide (Welbaum, 2015). As a last resort, you can use a weak solution of potassium permanganate (1–2 g per 10 l of water), but it kills not only pathogens but also beneficial microflora, so use it only locally – in holes.

Step 9. Prepare Planting Holes

On the day of planting or the day before, make holes 10–15 cm deep and 20–25 cm in diameter. Distance between holes:

• For determinate (short) varieties: 40–50 cm in the row, 60–70 cm between rows.
• For indeterminate (tall, trellised) varieties: 50–60 cm in the row, 80–90 cm between rows (Heuvelink, 2018).

In each hole you can add:

• A handful of humus or vermicompost (0.5–1 kg).
• 10–15 g of superphosphate (for initial root nutrition).
• If the soil is acidic – 1 tablespoon of dolomite lime directly into the hole.

Mix all this with the soil at the bottom of the hole.

Step 10. Water the Holes

An hour before planting, thoroughly water each hole (2–3 l). This will create a moist layer for the roots and reduce transplant stress.

Step 11. Plant with Deepening

Tomatoes can be planted deeper than they grew in the pot – up to the first true leaves. On the stem that ends up underground, additional roots will form, enhancing nutrition and plant stability (Jones, 2008; Swiader and Ware, 1992).

Key Difference: Controlled Environment vs. Natural Factors

In open ground, you work with the natural soil profile, where processes depend on weather, precipitation, and temperature. In a greenhouse, you create an artificial environment where you can regulate humidity, watering, and soil composition, but you pay for this with accelerated soil depletion and disease accumulation (Heuvelink, 2018).

1. Timing of Preparation

Open ground:

• Start preparation in autumn – liming, main application of organic matter and phosphorus fertilisers (Swiader and Ware, 1992).
• In spring – only light loosening and final nitrogen application 2–3 weeks before planting, when the soil warms to +14 °C at a depth of 10–15 cm (Jones, 2008).
• Do not rush! Planting in cold soil delays root development and provokes rots (Autko et al., 2012).

Greenhouse:

• Preparation can start early spring (March–April), because you can accelerate soil warming (e.g., by watering with warm water or covering with black film) (Heuvelink, 2018).
• Main fertiliser application – 2–3 weeks before planting, but taking into account that mineralisation processes are faster in the greenhouse (Hochmuth and Sideman, 2023).
• Important: do not overheat the soil before planting – the optimal root temperature is +18…+22 °C. Above +25 °C, roots absorb nutrients poorly (Swiader and Ware, 1992).

2. Drainage and Water Regime

Open ground:

• If the plot is waterlogged, be sure to make raised beds (ridges) 20–30 cm high – this will save roots from water stagnation after rains (Gould, 1992).
• On sandy soils – improve water‑holding capacity with organic matter and mulching (Jones, 2008).

Greenhouse:

• Drainage is critical because there is no natural evaporation and precipitation. Water stagnation in a greenhouse leads to rapid development of root rots (Heuvelink, 2018).
• If you use in‑ground beds, be sure to make them high (30–40 cm) and with a slope for draining excess water.
• In a greenhouse, under no circumstances create closed water “cushions” – use drainage ditches or lay drainage pipes (Welbaum, 2015).

3. Fertility and Nutrition

Open ground:

• Open‑ground soil has a natural reserve of nutrients that mineralise gradually (Swiader and Ware, 1992).
• Organic matter (compost, humus) is applied once every 2–3 years in large volumes (10–20 kg/m²) under autumn digging (Jones, 2008).
• Nitrogen, phosphorus, and potassium – according to standard schemes, but with adjustment for leaching (e.g., on sands, nitrogen is applied in split doses) (Hochmuth and Sideman, 2023).

Greenhouse:

• Greenhouse soil depletes faster because plants grow more intensively and yields are higher (Heuvelink, 2018).
• Organic matter is applied annually (8–12 kg/m²), but it is better to use well‑rotted compost or vermicompost to avoid salinisation (Welbaum, 2015).
• Special attention – to salinisation! In a greenhouse, due to the limited soil volume and abundant watering, salts accumulate faster. Periodically (every 2–3 years) carry out leaching – abundant watering with clean water without fertilisers (Hochmuth and Sideman, 2023).
• Potassium and phosphorus in the greenhouse need to be applied more fractionally than in open ground, as they are removed faster with the harvest (Atherton and Rudich, 1986).

4. Acidity (pH)

Open ground:

• Liming is done in autumn, because lime acts slowly (Hochmuth and Sideman, 2023).
• Check pH once a year, especially after rainy seasons, when calcium is leached.

Greenhouse:

• pH in the greenhouse changes faster: fertilising with ammonium nitrate or urea acidifies the soil, while liming (dolomite) alkalises it. Monitor pH every 2–3 months (Welbaum, 2015; Heuvelink, 2018).
• If pH drops below 6.0, apply dolomite lime in a thin layer on the surface and gently incorporate without deep digging (so as not to disturb the structure).

5. Soil Disinfection

Open ground:

• The main method is crop rotation (return tomatoes to the same place no earlier than after 3–4 years) (Jones, 2008).
• Additionally – watering holes with biological products (Trichoderma, Fitosporin) before planting (Welbaum, 2015).
• If there were disease outbreaks, in autumn – deep digging with turning the layer and adding organic matter.

Greenhouse:

• Diseases accumulate faster, so disinfection is mandatory (Heuvelink, 2018).
• The best method is steam sterilisation (heating the soil to +80…+90 °C for 30–40 minutes). If impossible – replace the top layer (20–30 cm) with new soil (Welbaum, 2015).
• Chemical disinfection (formalin, copper sulfate) in greenhouses is used with caution, as they kill beneficial microflora. Biological products (Trichoderma, pseudomonads) are safer – apply them 2–3 weeks before planting (Welbaum, 2015).

6. Structure and Loosening

Open ground:

• The soil is dug deeply (25–30 cm) once a year (autumn or spring). Additional loosening – only before planting (with a rake or cultivator) (Swiader and Ware, 1992).
• After rains, the top layer may become compacted – be sure to loosen between rows, but shallowly (5–7 cm) so as not to damage roots.

Greenhouse:

• Deep digging in the greenhouse is done once a year (autumn or spring), but additionally during the season the soil is loosened superficially to break the crust and improve aeration (Heuvelink, 2018).
• Important: in the greenhouse, it is not recommended to dig deeply frequently, as this disturbs structure and accelerates organic matter loss. It is better to use surface loosening and mulching (Welbaum, 2015).
• To improve structure in the greenhouse, add vermiculite or perlite – they create additional pores and improve drainage (Hochmuth and Sideman, 2023).

7. Soil Temperature Regime

Open ground:

• Soil warming depends on weather. Tomatoes are planted when the temperature at a depth of 10 cm stably exceeds +14 °C (Swiader and Ware, 1992).
• To accelerate warming, use black mulch (film, agrofabric) – it attracts solar heat and raises the temperature by 2–3 °C (Gould, 1992).

Greenhouse:

• Soil can be warmed artificially (warm watering, soil heating system) (Heuvelink, 2018).
• Important: do not overheat! Temperatures above +28 °C negatively affect the root system and calcium uptake, provoking blossom‑end rot (Jones, 2008).
• In hot weather, the greenhouse must be ventilated, and the soil mulched with light mulch (straw, white agrotextile) to reduce overheating (Welbaum, 2015).

Quick Cheat Sheet

Now you are ready to adapt soil preparation to your conditions – greenhouse or open ground. In the next chapter, we will discuss common mistakes that even experienced gardeners make, so that you can avoid them.

Mistake 1. Planting in cold, unheated soil

Essence: Planting seedlings without waiting for stable warming condemns roots to stress. At temperatures below +14 °C, tomato roots practically do not absorb phosphorus and water, and growth processes slow down (Swiader and Ware, 1992; Jones, 2008). Instead of active growth, the plant “sits still” and becomes vulnerable to root rots.

How to avoid:

• Measure soil temperature at a depth of 10–15 cm in the morning, at the coldest time of day. It should be stably above +14 °C for 3–5 days (Swiader and Ware, 1992).
• To accelerate warming, use black mulch (film, agrofabric) 2–3 weeks before planting – it raises temperature by 2–4 °C (Gould, 1992).
• In a greenhouse – water the beds with warm water (+25…+30 °C) the day before planting (Heuvelink, 2018).

Mistake 2. Excess fresh manure

Essence: Many think that the more manure, the better. But fresh manure (especially cow manure) contains a lot of ammonia, which burns tender roots, as well as weed seeds and pathogens. Moreover, excess readily available nitrogen causes lush green growth at the expense of fruiting (Jones, 2008; Gould, 1992).

How to avoid:

• Use only well‑rotted manure (aged at least 6–8 months) or compost.
• Apply organic matter in autumn under digging, not in spring just before planting (Swiader and Ware, 1992).
• Rate for tomatoes: no more than 10–15 kg/m² on medium soils (Jones, 2008).

Mistake 3. Over‑feeding with nitrogen (especially during fruiting)

Essence: Excess nitrogen is one of the main causes of tomato “luxuriant growth”. Plants build huge green mass, but flowering and fruit set are delayed. Moreover, nitrogen overload reduces disease resistance (late blight, grey mould) and impairs fruit quality (Atherton and Rudich, 1986).

How to avoid:

• Total nitrogen dose per season should not exceed 30–60 g/m² of pure substance (Swiader and Ware, 1992).
• Apply nitrogen in splits: ⅔ before planting (under digging), ⅓ – in the first half of the growing season (2–3 weeks after transplanting) (Gould, 1992).
• As soon as mass fruiting begins, stop nitrogen top dressings completely and switch to potassium‑phosphorus (Atherton and Rudich, 1986).

Mistake 4. Ignoring acidity (pH)

Essence: Applying fertilisers “by eye” without checking pH is shooting in the dark. In acidic soil (pH < 5.5), phosphorus and potassium are bound into unavailable forms, and aluminium and manganese become toxic (Jones, 2008). In alkaline soil (pH > 7.0), plants suffer from iron, boron, and zinc deficiencies, manifesting as chlorosis of young leaves (Hochmuth and Sideman, 2023).

How to avoid:

• Always measure pH before applying fertilisers, using litmus strips or a portable pH meter (Hochmuth and Sideman, 2023).
• If pH < 6.0 – apply dolomite lime (200–600 g/m² depending on soil) in autumn (Swiader and Ware, 1992).
• If pH > 7.0 – use acidifying watering (e.g., water with citric acid) or apply elemental sulfur (3–6 months before planting) (Hochmuth and Sideman, 2023).

Mistake 5. Planting in dense, unprepared soil

Essence: Superficial digging, when large clods are not broken and the surface is not levelled, leads to the fact that tomato roots cannot penetrate deeply. As a result, the plant develops a shallow, weak root system that easily suffers from drying out and waterlogging (Autko et al., 2012).

How to avoid:

• Dig the plot to a full spade depth (25–30 cm) (Swiader and Ware, 1992).
• Break up large clods, but do not turn the soil to dust – the optimal structure is fine‑cloddy (Welbaum, 2015).
• 1–2 days before planting, go over with a rake to level the surface and break the crust (Gould, 1992).

Mistake 6. Overwatering or poor drainage

Essence: Tomatoes do not tolerate water stagnation at the roots. Overwatering leads to oxygen starvation, root system depression, and activation of pathogens (late blight, fusarium) (Jones, 2008). This is especially dangerous on heavy clay soils.

How to avoid:

• On plots with water stagnation, make raised beds (ridges) 20–30 cm high (Gould, 1992).
• In greenhouses, be sure to provide drainage – ditches, drain pipes, or a layer of gravel under the fertile layer (Heuvelink, 2018).
• Water only as the top layer dries (to a depth of 5–7 cm), not on a schedule (Welbaum, 2015).
• During rainy periods in open ground, cover plantings with film or make temporary shelters (Kemble et al., 2022).

Mistake 7. Ignoring crop rotation and contaminated soil

Essence: Annual planting of tomatoes in the same place leads to the accumulation of specific pathogens in the soil (fusarium, verticillium, root‑knot nematodes). Even ideal preparation will not save you if the soil is infected (Jones, 2008).

How to avoid:

• Return tomatoes to the same place no earlier than after 3–4 years (Swiader and Ware, 1992; Gould, 1992).
• In greenhouses where crop rotation is impossible – replace the top layer of soil (20–30 cm) every 3–4 years or carry out steam sterilisation (Heuvelink, 2018).
• Use biological products (Trichoderma, Fitosporin) to suppress pathogens directly in the holes when planting (Welbaum, 2015).

Summary: How Not to Make Mistakes

Now you have a complete guide – from theory to practical solutions and warnings. Preparing soil for tomatoes is not a complicated science, but a system of conscious actions. Give enough attention to this stage, and the plants will thank you with strong health and an abundant harvest of tasty, aromatic fruits. Good luck!