Care

Why loosen the soil in onion beds?

1. Breaking up the soil crust. After watering or rain, a dense crust forms on the soil surface. This significantly hinders oxygen access to the roots, which is necessary for plant respiration and nutrient uptake (Swiader & Ware, 1992). Furthermore, the hard crust physically impedes the growth of young, tender onion seedlings, especially in the "loop" stage when they are most vulnerable (Karataev and Sovetkina, 1984). Timely loosening breaks this crust, ensuring free air access.

2. Conserving moisture in the soil. By breaking the capillaries in the topsoil layer, loosening creates a mulching layer that prevents intensive moisture evaporation from the surface (Hochmuth & Sideman, 2023). This is particularly important for onions, which, despite the relative drought tolerance of their leaves, are very demanding of soil moisture due to the weak absorbing power of their roots (Autko et al., 2012). Loosening allows for reduced watering frequency and helps maintain a more stable water regime.

3. Weed control. Loosening between rows is one of the primary mechanical methods of weed control. Destroying weeds at their early stages of development reduces competition for moisture and nutrients, which is critically important for slowly growing onions at the beginning of the growing season (Nonnecke, 1989).

How to properly loosen onions: timing and depth

The loosening technique changes depending on the plant's development stage. The main rule is to be careful not to damage the shallow root system.

• First loosening: Performed immediately after emergence or, when grown from sets, after they have rooted. During this period, loosen the soil very carefully and to a shallow depth to avoid damaging the delicate roots. The treatment depth between rows can be 4-6 cm (Karataev and Sovetkina, 1984; Autko et al., 2012).

• Loosening during active growth: As plants grow and the root system develops, the loosening depth is gradually increased to 8-12 cm, especially on heavy soils. This helps break up denser layers, improve aeration, and facilitate water penetration deeper into the soil (Pantielev, 1986). However, as the bulb enlarges and roots approach the surface, the loosening depth near the plant should be reduced again to avoid damaging the base and the growing bulb.

• Stopping loosening: Once the bulbs begin to actively swell and their upper part (shoulders) emerges from the soil, loosening between rows is stopped. Excessive loosening during this period can damage the forming bulb. Typically, loosening is completed 2-3 weeks before harvest.

Practical tips

• Regularity: During the growing season, 4-6 loosening operations are usually carried out (Autko et al., 2012). The number of treatments depends on soil type, weather conditions, and the degree of weed infestation. On light sandy soils, loosening can be done less frequently; on heavy loams, more often.

• Connection with watering: Loosening is most effective after watering or rain. As soon as the water has been absorbed and the soil has dried slightly, loosening should be carried out immediately to break the forming crust and seal in the moisture.

• Tools: For small plantings, hand hoes, garden cultivators, or special loosening tools are convenient. For larger areas, cultivators are used between rows. The main thing is to ensure a sufficient protective zone width to avoid damaging the roots and the plant itself.

Conclusion: Loosening is one of the simplest and most effective techniques that helps create a favorable air and water regime in the soil for onions. Regular and skillful loosening promotes active root system growth, strengthens plants, and is the key to obtaining a high yield of large, healthy bulbs.

Why is weeding so important for onions?

1. Intense competition for resources. Weeds are generally more aggressive and grow faster than onions. They outgrow them and shade them. Their powerful root systems absorb water and nutrients from the soil faster, leaving the onions "hungry." Competition is especially dangerous during the seedling phase and during bulb formation (Swiader & Ware, 1992). Any suppression of onions by weeds before bulb formation begins will lead to a significant reduction in yield (Nonnecke, 1989).

2. Worsening of growth conditions. Dense weed thickets create a stagnant, humid microclimate near the soil surface. This promotes the development of fungal diseases, such as downy mildew (peronospora) and various rots (Autko et al., 2012). Additionally, weeds can serve as secondary hosts for onion pests, such as the onion fly.

3. Hindering maturation and harvest. Weeds left between rows can shade and "constrict" the bulbs, preventing their normal maturation. Closer to harvest, weeds interfere with the natural lodging and yellowing of leaves and significantly complicate mechanical or manual harvesting (Hochmuth & Sideman, 2023).

Methods and features of weeding

1. Manual weeding. This is the most labor-intensive but, for small areas and spot control, the most reliable method. It is particularly important to thoroughly weed onions during the "loop" stage and until 3-4 true leaves appear. During this period, young onion seedlings are very easily damaged, so all work should be done as carefully as possible (Swiader & Ware, 1992).

2. Mechanical weeding. Cultivators are used for inter-row cultivation in industrial and farming operations. Several inter-row treatments are usually carried out per season, combining them with loosening. It is important to remember the "protective zone" – the strip near the row where work is done manually to avoid damaging the onion roots (Autko et al., 2012).

3. Chemical weeding (herbicides). Herbicides are widely used in large-scale farming. It is important to understand that onions are very sensitive to chemicals, especially in the early stages of growth – the "loop" stage (first true leaf) (Swiader & Ware, 1992; Nonnecke, 1989). Therefore, the use of herbicides on onions is not recommended for home gardeners due to the high risk of damaging the crop itself. Herbicide application requires precise adherence to instructions and consideration of the plant's growth stage.

Strategy for successful weed control

It is most effective to control weeds by preventing them from growing. Here are a few key principles:

• Clean site. Do not plant onions in areas infested with perennial rhizomatous weeds (couch grass, ground elder) or sow thistle. Controlling them in onion plantings is extremely difficult.

• Timeliness. The main rule of weeding is not to let weeds grow. Remove them when they first appear. Young weeds are easily pulled out and haven't had time to cause significant harm. If you miss the moment, their roots can intertwine with the onion roots, and you risk pulling out the plant itself while weeding.

• Regularity. Don't just do one "big" weeding. It's better to do it frequently but in small amounts. Regular weed removal keeps the bed clean and is more effective than fighting already overgrown "jungles."

• Combination with other techniques. Weeding is closely related to loosening. Breaking the soil crust and loosening between rows simultaneously destroys weed seedlings. Use these techniques in combination. Mulching is also very helpful in weed control, but more on that in the next chapter.

Conclusion: Weeding is not just an aesthetic procedure but a vital measure in onion cultivation. Regular and timely weed removal allows onions to use soil resources unhindered, receive enough light, and stay healthy, ultimately leading to the formation of large, healthy, and well-storing bulbs.

Why mulch onions?

1. Conserving moisture in the soil. This is perhaps the main task of mulch. A layer of mulch prevents direct evaporation of moisture from the soil surface, significantly reducing the frequency of watering. For onions, which need a stable but not excessive moisture level, this is especially important since sharp moisture fluctuations can cause bulbs to crack or develop diseases (Hochmuth & Sideman, 2023).

2. Suppressing weed growth. A thick layer of organic mulch or black plastic film creates a physical barrier to light, without which the seeds of most weeds cannot germinate. This significantly eases the task of weeding and sometimes eliminates it altogether (Hochmuth & Sideman, 2023; Autko et al., 2012). Remember that onions are weak competitors in the fight against weeds, and mulch gives them a decisive advantage.

3. Regulating soil temperature. Mulch acts as a heat insulator:

• In spring, light-colored mulch (straw, mown grass) can slow down soil warming, so it should not be used too early. Black plastic film, on the other hand, attracts sunlight and significantly accelerates soil warming (Hochmuth & Sideman, 2023). This can be useful in cold climates for early sowing.
• In summer, mulch protects roots from overheating in hot weather. Soil overheating, especially on light sandy soils, inhibits the onion root system. Mulch maintains a more stable and comfortable temperature in the root zone.

4. Reducing the risk of diseases. Organic mulch, as it decomposes, enriches the soil with humus. However, most importantly, mulch prevents soil containing pathogenic fungi and bacteria from splashing onto the leaves and bulbs during watering or rain, thus reducing the risk of infection (Hochmuth & Sideman, 2023). Also, mulch prevents bulbs from directly contacting wet soil, preventing rot development.

5. Preventing soil compaction. A layer of mulch softens the impact of raindrops and prevents the formation of a soil crust, keeping the soil loose and breathable, which is especially valuable for the shallow root system of onions (Hochmuth & Sideman, 2023).

Types of mulch for onions

Both organic and synthetic materials can be used for bulb onions. Each has its own characteristics.

Organic mulch (for small areas and gardeners):

• Mown grass (without seeds). A good option. It's important to dry it before use to prevent matting and rotting. The layer should be about 5-7 cm.
• Straw. Allows excellent air and water passage, decomposes slowly. Well suited for onions as it does not compact heavily.
• Rotted sawdust or wood shavings. Retain moisture well but can acidify the soil and "bind" nitrogen during decomposition. For onions, it is better to use rotted sawdust and be sure to compensate for nitrogen loss with additional feeding.
• Peat (high-moor, neutralized). Protects well against overheating and retains moisture.
• Compost or humus. Not only mulches but also serves as an excellent fertilizer. However, such mulch attracts earthworms, which aerate the soil but can also expose onion roots.

Synthetic mulch (for farmers and large plantings):

• Black plastic film. The most popular option for commercial cultivation. It most effectively suppresses weeds, retains moisture excellently, and warms the soil quickly in spring. However, it must be laid before planting and removed from the field after harvest, creating a disposal problem (Hochmuth & Sideman, 2023). Onions are planted or sown in slits in the film.
• Biodegradable films. A modern alternative to black film. They decompose in the soil under the action of microorganisms, eliminating the need for collection and disposal (Hochmuth & Sideman, 2023). However, they are more expensive and may decompose faster than needed.
• White or white-black film. Used in southern regions to protect roots from severe overheating, as it reflects sunlight (Hochmuth & Sideman, 2023).

How to properly mulch onions?

1. Before mulching, be sure to remove all weeds and, if using organic mulch, water so that the soil is moist.

2. The layer of organic mulch should be between 3 to 5 cm, but no more than 7 cm. A layer that is too thick can impede air access to the roots, while a layer that is too thin will be ineffective.

3. Do not mulch too early in spring. Wait until the soil has warmed up well, otherwise, you will only slow down plant development. The optimal time is when the onions are actively growing (phase of 3-4 true leaves).

4. Monitor the condition of the mulch. Organic mulch decomposes over time, and its layer needs to be renewed.

5. When using black film, it is important to press it firmly to the ground to prevent wind from getting underneath and condensation from forming. Before laying, the soil should be thoroughly prepared, fertilized, and equipped with a drip irrigation system (Hochmuth & Sideman, 2023).

Warning: Do not use fresh sawdust or fresh, unrotted straw with many cereal weeds. Also, avoid using mulch from plants affected by diseases.

Conclusion: Mulching is an investment of time and resources that pays off many times over. Properly selected and timely laid mulch eliminates many problems, allowing for higher and more stable yields of large, clean, and healthy onions, significantly simplifying their care.

Why thin onions?

1. Ensuring sufficient feeding area. Each onion plant needs a certain amount of space to form a full-fledged bulb. In dense sowings, plants compete for light, water, and nutrients. The result is many small, unmarketable bulbs that also store poorly. As Nonnecke (1989) notes, it is competition between plants that is the main reason for obtaining poor-quality crops in too dense sowings.

2. Influence on bulb shape and size. The distance between plants in a row is a key factor determining bulb size. A wider spacing (up to 4 inches / 10 cm) promotes the formation of large, smooth bulbs. Closer spacing yields a higher total yield per unit area, but the proportion of large bulbs decreases (Swiader & Ware, 1992). Thus, thinning allows the gardener to choose: get maximum greens or large bulbs for storage.

3. Reducing the risk of diseases. Dense plantings are poorly ventilated, creating a humid microclimate near the soil surface. This is an ideal environment for the development of fungal diseases, such as downy mildew (peronospora) and various rots (Autko et al., 2012). Thinning improves air circulation, making plants healthier.

When and how to properly thin onions?

Timing depends on the growing method:

1. When sowing seeds (nigella) in an annual crop:

• This is the most critical case. The first thinning is carried out in the phase of 1-2 true leaves. The goal is to remove the weakest and most twisted plants, leaving only the strongest and healthiest ones.
• The second, final thinning is carried out in the phase of 3-4 true leaves, when the plants have grown a bit and their vigor is more visible. It is at this stage that the final distance between plants is established (Autko et al., 2012; Karataev and Sovetkina, 1984).

2. When planting sets: Thinning is generally not required, as sets are planted immediately with the desired spacing. If the set seedlings are too dense, they can be thinned, but this rarely happens.

Recommendations on plant density

• For obtaining large bulbs (repa): The optimal distance between plants in a row is 6-10 cm (2-4 inches), depending on the variety (Swiader & Ware, 1992; Nonnecke, 1989). For large-fruited "sweet" varieties (e.g., Spanish), the distance should be greater – up to 10-15 cm. On peat (muck) soils, which are looser, bulbs can "push apart" during growth, so slightly denser placement is permissible than on mineral soils (Nonnecke, 1989).
• For obtaining small onions for greens or canning: The distance can be reduced to 3-5 cm (Autko et al., 2012). For greens, you can skip thinning altogether and simply pull plants as they grow for bunching.
• Optimal density: In commercial cultivation, to obtain bulbs 5-6 cm in diameter, it is recommended to maintain a density of about 250,000 plants per hectare (which roughly corresponds to a spacing of 10-12 cm in the row with 30-40 cm between rows) (Swiader & Ware, 1992).

Practical tips for thinning

1. Don't pull, snip. To avoid damaging the roots of the remaining plants, it is better not to yank out the excess onion seedlings but to carefully snip them off or cut them with scissors at ground level. This is especially important in the early stages.

2. Work in moist soil. Thinning is much easier after watering or rain, when the soil is soft and roots come out more easily.

3. Don't rush the final thinning. Carry out the second thinning when the plants have grown enough to assess their potential. However, don't delay so that plants start competing with each other.

4. Use the removed plants. Carefully pulled young plants with roots can be used as green onions (Nonnecke, 1989). This is a great way to get early vitamin-rich produce.

Conclusion: Thinning is a key technique that allows the gardener to take control of the quality of the future harvest. Timely and correct thinning provides each plant with sufficient space for development, reduces the risk of diseases, and allows you to obtain precisely the bulbs you need: large for storage or small for greens and canning. It's not just about removing excess; it's about conscious growth management.

Why do onions bolt?

The main cause of bolting is the exposure of plants that have reached a certain size (phase of 3-5 true leaves) to low positive temperatures (from +5 to +10°C). This phenomenon is called vernalization (Swiader & Ware, 1992; Nonnecke, 1989). It is important to understand that:

• The cold exposure must be sufficiently long (several weeks). Short-term frosts down to -1°C, as a rule, do not cause bolting but only damage the leaves (Autko et al., 2012; Nonnecke, 1989).
• Bolting is influenced not only by cold but also by plant size. Small plants (in the phase up to 2-3 leaves) do not respond to cold – their juvenile period is not yet complete. However, large plants, transplanted or sown early, are already ready to perceive cold and may flower.
• Day length (photoperiod) is not a trigger for bolting, as is sometimes mistakenly believed. Bolting is caused specifically by temperature (Swiader & Ware, 1992).

Thus, bolting is the result of the coincidence of two factors: large plant size and exposure to low temperatures at the beginning of the growing season.

How to prevent bolting?

Prevention of bolting begins long before planting and continues through all stages of cultivation.

1. Correct choice of planting material (sets)

This is the most important factor (Swiader & Ware, 1992; Nonnecke, 1989).

• Use small sets (1-1.5 cm in diameter). Small bulbs have fewer nutrient reserves and are less likely to transition to flowering. Large sets (over 2.5 cm), on the other hand, are prone to bolting.
• Buy sets from reputable producers. Specialized farms grow sets using special storage technologies that suppress the development of flower buds.

2. Proper storage of sets

The temperature regime during storage directly affects the tendency to bolt (Nonnecke, 1989; Autko et al., 2012).

• Cold method (at -1...-3°C). Storage at low temperatures prevents the awakening of flower buds. This method is used in commercial storage facilities.
• Warm method (at +18...+20°C). Storage at room temperature is also acceptable, provided it does not drop below +15°C. A drop in temperature during storage is a direct path to bolting.
• Warm-cold method. Optimal for many regions. In autumn and spring, sets are stored at +18...+20°C, and in the middle of winter, the temperature is lowered to -1...-3°C, then raised again. This method reduces losses from diseases and drying but requires strict control (Autko et al., 2012).

3. Warming sets before planting

If you are unsure about the storage conditions of the purchased sets, perform heat treatment 2-3 weeks before planting (Autko et al., 2012; Nonnecke, 1989; Swiader & Ware, 1992).

• Warm the sets at a temperature of +40...+42°C for 8 hours or at +45...+47°C for 10-12 hours (in a stream of warm air).
• This procedure destroys the primordia of flower shoots and significantly reduces the risk of bolting.
• Important: The warming must be uniform. At home, you can use an oven with the door open or place the sets on a radiator, but the temperature must not exceed the specified values, otherwise, you can damage the bulbs themselves.

4. Correct planting date

Plant the sets at the optimal time for your region, when the soil has warmed up to +10...+12°C (Autko et al., 2012; Swiader & Ware, 1992). Do not rush into early planting if there is a risk of return frosts.

5. Choosing bolt-resistant varieties

Some varieties (especially modern F1 hybrids) have genetic resistance to bolting. When choosing a variety for your region, check this characteristic in the description (Autko et al., 2012).

What to do if flower stalks have already appeared?

If several plants have still thrown out flower stalks, do not despair. Do the following:

1. Immediately remove the stalk. Break it out as early as possible, at the very base (near the bulb neck). The sooner this is done, the greater the chance that the bulb will still be able to fill out, although it will be smaller than that of non-bolting plants.

2. Leave one or two plants for seeds. If you want to get your own seeds (nigella), leave the strongest plants, let them flower and set seeds. Do not harvest such plants for storage.

3. Use bolting plants first. Even if the bulb is small and coarse, it can be used for summer consumption, salads, and cooking. Do not store such bulbs.

Conclusion: Bolting control is a complex task that begins with the correct choice and storage of sets and ends with timely planting. Understanding that bolting is caused by a combination of cold and large plant size allows the gardener to apply preventive measures. Warming the sets before planting is the most reliable and accessible way for home gardeners to guarantee avoiding this problem.

Signs of onion overheating

• Yellowing and drying of leaf tips. This is one of the first signals that the plant is uncomfortable.
• Wilting and loss of leaf turgor during the day. Leaves may lodge, though they recover at night.
• Premature lodging of tops. If onions lodge long before the natural ripening period, it could be a consequence of heat stress.
• Cessation of bulb growth. In extreme heat, bulb growth may stop completely.

How to protect onions from overheating?

Protection from overheating is a set of measures aimed at reducing both soil and air temperatures in the plant growth zone.

1. Correct choice of planting date

This is the simplest and most effective way to avoid overheating. Plant onions as early as possible so that their active growth and bulb formation coincide with the cooler spring and early summer months. In most regions, this means planting sets or sowing seeds immediately after the soil warms up to +8...+10°C (Nonnecke, 1989). Delaying planting causes the bulb formation phase to coincide with the peak of summer heat, which is extremely unfavorable.

2. Using mulch to reduce soil temperature

As we discussed in Chapter 3, mulch is an excellent temperature regulator.

• In hot climates, light-colored mulch is particularly effective: straw, mown grass, white agrofabric, or white/white-black plastic film. Light materials reflect sunlight, preventing the soil from overheating. In southern regions, some farmers even specially paint black mulch white (Hochmuth & Sideman, 2023).
• Black film, which is so good for warming the soil in spring, can cause root overheating in summer. In southern regions, its use is not recommended, or it must be additionally shaded with a light material (Hochmuth & Sideman, 2023).

3. Regular and proper watering

Water is a natural temperature regulator.

• Water onions in the heat. Moist soil heats up more slowly than dry soil. Maintain soil moisture at 75-80% of field capacity during the active growth period (Autko et al., 2012).
• Water at the right time. The best time to water in hot weather is early morning. This allows plants to store moisture before the daytime heat arrives and reduces the risk of leaf burns from water droplets that can act as lenses. Evening watering is also acceptable, but it can lead to soil being too wet overnight, promoting fungal diseases.
• Sprinkling. In hot weather, it is useful to carry out refreshing sprinkler irrigation in the morning or evening hours. This lowers the air temperature around the plants and improves their condition.

4. Shading

For small areas, artificial shading can be used.

• Shading nets. Special garden nets with different shading degrees (e.g., 30-50%) can be stretched over the beds during the hottest period. This lowers the air temperature and protects the leaves from direct sunburn.
• Companion plants. Tall crops, such as corn or sunflowers, planted on the south side of the bed, can create light shade during the hottest hours (Hochmuth & Sideman, 2023). However, it is important that they do not shade the onions too much.

5. Loosening after watering

Loosening after watering, as discussed in Chapter 1, breaks the capillaries through which moisture rises to the surface and evaporates. This helps retain moisture in the soil and, consequently, prevents it from overheating.

6. Response to heat stress

If the onions have already overheated (leaves have lost turgor), do not try to immediately "flood" them with cold water. This can cause shock. It is better to carry out a light refreshing sprinkler irrigation in the morning, and the next day, a full watering with loosening.

Important nuances to remember:

• High temperatures during bulb formation (above +25...+28°C) can slow down the process but not stop it completely. However, during prolonged heat above +30°C, bulb growth may stop entirely.
• Onions grown from seeds (nigella) are more heat-resistant than onions grown from sets. This is due to their more powerful root system.
• Different varieties react differently to heat. Southern short-day varieties are more heat-tolerant than northern long-day varieties. Choose varieties adapted to your region.

Conclusion: Protection from overheating is a complex task requiring strategic planning from the gardener. Choosing the correct planting date, using light-colored mulch, regular watering, and, if necessary, artificial shading – all this helps minimize the negative impact of high temperatures, provide onions with comfortable conditions for growth, and ultimately obtain a full-fledged, high-quality harvest even in hot summers.

Why is soil compaction dangerous for onions?

1. Hindered oxygen access to roots. Onion roots need oxygen for respiration and active nutrient uptake. In dense, slaked soil, the oxygen content drops sharply. Roots "suffocate," stop growing, and die. The plant stops receiving nutrition, leaves turn yellow, and the bulb does not fill out (Swiader & Ware, 1992).

2. Disruption of the water regime. Compacted soil absorbs water poorly. After watering or rain, water either stagnates on the surface, forming puddles, or runs off without penetrating deep. At the same time, in dense soil, capillaries work too actively, and moisture quickly evaporates from the top layer, leaving the roots dry. This creates a dangerous imbalance for onions: the top layer is dried out, while below it is waterlogged and oxygen-deprived (Hochmuth & Sideman, 2023).

3. Formation of a soil crust. This is the most noticeable and dangerous form of compaction. A hard crust on the surface, forming after rain or watering, physically prevents seedling emergence. Young, thin onion "loops" cannot break through it, and the seedlings die (Karataev and Sovetkina, 1984; Pantielev, 1986).

4. Deformation of bulbs. On heavy, compacted soils, especially with dense planting, bulbs cannot expand normally. They grow small, flattened, and misshapen. On loose, cultivated soils, bulbs are round and smooth (Nonnecke, 1989; Autko et al., 2012).

What leads to soil compaction?

• Natural factors: Rain, especially heavy showers, and drip irrigation. Water drops break down soil aggregates, and fine particles fill the pores, creating a crust.
• Anthropogenic factors: Walking on beds, working with heavy tools, vehicle traffic (for large fields). Working on wet soil is especially dangerous – it compresses most severely at this time.
• Errors in agronomy: Lack of organic matter, which is a natural "loosener," and constant tillage to the same depth (formation of a "plow pan").

How to control and prevent compaction?

Fighting compaction is, essentially, a fight to preserve soil structure.

1. Choosing a site with the correct soil type

• The best soils for onions are loose, structural loams and sandy loams, rich in organic matter (humus). Such soils are less prone to compaction.
• Heavy clay and slaking soils are unsuitable for onions, especially for growing from seeds (Autko et al., 2012). If you have such a plot, serious measures are needed to improve the structure (adding sand and organic matter).

2. Regular and proper loosening

As we discussed in Chapter 1, loosening is the main tool for combating soil crust.

• Carry out loosening after each watering or rain, as soon as the soil has dried slightly.
• First loosening – immediately after emergence, very shallow (4-6 cm).
• During active growth – deeper (8-10 cm), but always considering the width of the protective zone to avoid damaging the roots (Autko et al., 2012; Karataev and Sovetkina, 1984).
• As the bulb grows and begins to protrude from the soil, the loosening depth is reduced again and stopped 2-3 weeks before harvest.

3. Application of organic fertilizers

Humus, compost, peat (neutralized) not only feed plants but are also excellent soil conditioners. They make clay soil more breathable and sandy soil more cohesive, capable of retaining moisture. Apply organic matter in autumn or spring (Autko et al., 2012; Nonnecke, 1989).

4. Mulching

Mulch not only controls weeds and regulates temperature but also performs a crucial anti-erosion function. It softens the impact of raindrops and prevents crust formation on the surface (Hochmuth & Sideman, 2023). This is one of the most passive yet effective methods of compaction control.

5. Minimizing physical impact

• Do not work on wet soil. Do not walk on beds or carry out any treatments when the ground is wet. Wait until it dries.
• Use boards or paths. If you need to walk over the bed, use wide boards to distribute the load and avoid compacting the soil.
• Create raised beds. On heavy soils, it is recommended to grow onions on narrow-profile (raised) beds. This improves drainage, soil structure, and facilitates loosening (Autko et al., 2012).

Special attention: combating the "plow pan"

On large areas with constant plowing to the same depth, a dense layer – the "plow pan" – forms. It prevents roots from penetrating deeper than 20-25 cm. To combat it, deep loosening (subsoiling) or plowing to different depths is used. For a home garden, it is sufficient to occasionally (every 3-4 years) carry out deep digging with soil inversion, but in the fall, so that the structure recovers by spring.

Conclusion: Compaction control is ongoing work aimed at maintaining soil in a loose, structural state. It is not a one-time event but a set of measures: regular loosening, mulching, adding organic matter, and a sensible approach to walking on beds. Remember: the looser and "healthier" the soil, the easier it is for onions to grow in it, the larger and smoother the bulbs will be, and the less time and effort you will spend on caring for them.

Agronomic mistakes

1. Incorrect choice of planting date

• Mistake: Planting sets too early in cold, unheated soil.
• Consequences: The sets, being in cold soil, undergo vernalization instead of active growth. This leads to massive bolting (formation of flower stalks), making bulbs unsuitable for storage (Nonnecke, 1989; Swiader & Ware, 1992). Additionally, prolonged cold can trigger the development of rots.
• How to avoid: Wait until the soil warms up to +10...+12°C. Do not rely on calendar dates but on the actual soil temperature and weather forecast.

2. Incorrect watering

• Mistake: Frequent, shallow watering that only wets the topsoil.
• Consequences: Onion roots, seeking moisture, do not develop deeply but remain in the surface layer. This makes plants vulnerable to even the slightest drought. Furthermore, frequent shallow watering contributes to the formation of a soil crust and compaction.
• How to avoid: Water less frequently but more deeply, wetting the soil to a depth of 15-20 cm. During active growth and bulb formation, watering should be especially intensive (Nonnecke, 1989; Swiader & Ware, 1992).

3. Ignoring loosening

• Mistake: Lack of regular loosening, especially after watering and rain.
• Consequences: A dense soil crust forms, blocking oxygen access to the roots. Roots "suffocate," plant growth slows, and bulbs form small and deformed (Karataev and Sovetkina, 1984).
• How to avoid: Loosen the soil after each watering as soon as it dries slightly. This is your main tool in the fight for the onion's "lungs."

Mistakes with planting material

4. Using large sets

• Mistake: Planting large sets (over 2.5 cm in diameter) for bulb production.
• Consequences: Large sets have a large supply of nutrients and are highly likely to bolt, especially with improper storage or early planting. Bulbs grown from large sets store worse (Swiader & Ware, 1992; Nonnecke, 1989).
• How to avoid: Use small sets (1-1.5 cm) for bulbs. Leave large sets for greens or early summer consumption.

5. Improper storage of sets

• Mistake: Storing sets at unstable, too low temperatures that fluctuate around critical values (+5...+10°C).
• Consequences: It is in this temperature range that flower buds are initiated. In spring, such sets will bolt en masse (Nonnecke, 1989).
• How to avoid: Store sets either at warm temperatures (+18...+22°C) or cold temperatures (-1...-3°C). Avoid intermediate temperatures. If you bought sets and don't know how they were stored, be sure to carry out pre-planting warming (at +40...+42°C for 8 hours) (Autko et al., 2012).

6. Planting sets too deep or too shallow

• Mistake: Burying sets more than 4-6 cm deep.
• Consequences: Deep planting delays bulb maturation, makes the neck thick and poorly drying, which reduces storage ability and provokes neck rot (Nonnecke, 1989; Karataev and Sovetkina, 1984). Too shallow planting (less than 2 cm) can lead to bulbs pushing out of the ground and drying out.
• How to avoid: Plant sets so that there is about 2 cm from the top of the bulb (shoulders) to the soil surface. The planting depth should be 4-6 cm, depending on the size of the set and soil type (Autko et al., 2012).

Mistakes in care

7. Ignoring the appearance of flower stalks

• Mistake: Not removing emerging flower stalks, hoping they won't affect bulb growth.
• Consequences: The plant wastes energy on flowering, the bulb stops growing, becomes coarse, with a thick neck, and is unsuitable for storage.
• How to avoid: As soon as you notice a stalk, break it out at the very base. Eat such bulbs first; do not store them.

8. Excessive use of nitrogen fertilizers in the second half of the growing season

• Mistake: Applying nitrogen fertilizers (manure, grass tea, saltpeter) during bulb formation and maturation.
• Consequences: Nitrogen stimulates green mass growth, delays bulb maturation, makes the neck thick and juicy, which sharply reduces storage ability and provokes disease development during storage (Nonnecke, 1989; Swiader & Ware, 1992).
• How to avoid: Nitrogen fertilization is effective only at the beginning of the growing season, for building leaf mass. After bulb formation begins, switch to phosphorus-potassium fertilizers.

Mistakes related to harvesting and storage

9. Delayed harvest

• Mistake: Delaying harvest after the onions have completely lodged and leaves have yellowed and dried.
• Consequences: Over-mature onions may start new growth in wet weather, making them unsuitable for storage. Additionally, bulbs may crack and suffer more from neck rot (Swiader & Ware, 1992).
• How to avoid: Harvest onions when 60-80% of the leaves have yellowed and lodged. This usually occurs in late July – August, depending on the region and variety (Autko et al., 2012).

10. Insufficient drying before storage

• Mistake: Storing onions with a moist, undried neck.
• Consequences: A moist neck is a gateway for infection. Infection by neck rot (Botrytis spp.) occurs precisely at the cut site and leads to mass spoilage of onions during storage (Swiader & Ware, 1992; Nonnecke, 1989).
• How to avoid: Be sure to dry the onions after harvest for 1-2 weeks in a dry, warm, well-ventilated place (attic, under a canopy, in a dryer with active ventilation). The neck should be completely dry and tightly closed.

Conclusion: Most mistakes in growing onions stem from a lack of understanding of their biology. Careful attention to the choice of planting material, planting dates, watering, and, most importantly, timely drying after harvest, is the key to success. By avoiding these ten typical mistakes, you will be able to obtain stable yields of large, healthy onions that will store well all winter.

Conclusion for the entire guide

We have examined eight key aspects of bulb onion care: from loosening and weeding to mulching, thinning, and protection from bolting and overheating. Caring for onions is a systematic task where every element is important and interconnected. Following these simple but scientifically based rules will allow you to avoid typical mistakes and obtain excellent yields that will delight you and your loved ones. Good luck in your gardens!