Growing from seed in one season

1.1. The Main Secret: Response to Day Length

Onion is a long-day plant. This means that bulb formation is triggered only when the day length reaches a certain threshold value (the so-called "critical day length") (Brewster 2008). For most varieties suitable for growing in temperate climates, this threshold is 14–16 hours.

Once the day length exceeds this threshold, leaf growth slows down, and the outflow of nutrients from the green mass to the leaf bases begins, forming the bulb. If the day length is too short (less than 12–13 hours), the onion may not form a bulb at all, instead continuing to grow green mass, even if all other conditions are ideal (Nonnecke 1989).

1.2. Choosing a Strategy Depending on the Region

Strategy A: Temperate Zone and Regions with Long Days (Northern and Central Regions of Russia, Northern Europe, Canada, Northern USA)

In these regions, the summer day length reaches the required length (more than 15–16 hours), creating ideal conditions for onions. Here, growing from seeds in one season is the main and most economical method.

Timing: Sowing is done in early spring, as soon as the soil allows. The key task is to give the plants enough time to build up leaf mass before the "bulb-forming" photoperiod arrives. Late sowings will shorten the vegetative period before bulb formation begins and lead to a small harvest (Brewster 2008).

Varieties: It is necessary to use early-ripening and mid-ripening varieties adapted to long days. Southern short-day varieties in your conditions will start forming a bulb too early and produce a small yield, while very late northern varieties may not have time to ripen before autumn (Balashev and Zeman 1981).

Strategy B: Southern Regions with Mild Winters (Central Asia, Transcaucasia, Southern USA, Mediterranean)

In these regions, the day length may not be long enough for some varieties, but there is another advantage—a mild winter. Here, autumn and summer-autumn sowings are widely used to obtain a bulb onion in one season (Balashev and Zeman 1981).

• Autumn Sowing: Seeds are sown in autumn (November–December) so that they swell but do not germinate before spring. The plants start growing very early, use winter moisture, and form a more powerful root system. This gives them a significant advantage and increases yield by 10–15% compared to spring sowing. However, such plantings can produce more bolting (flower stalk formation) in the first year, so onions from autumn sowing are not suitable for long-term storage and should be sold first.
• Summer-Autumn Sowing (August–September): With this method, the plants manage to develop a powerful leaf apparatus before winter and overwinter in the rosette phase. The harvest is gathered as early as May–June of the following year. This method is very productive, but again, it produces a high percentage of bolting plants and stores poorly.

Important: In the hot and humid climate of the tropics and subtropics, where the day length is always short, it is generally impossible to grow a bulb onion from seeds in one season without special locally bred varieties or the use of agronomic techniques (e.g., extending the day length with artificial lighting).

1.3. What Are the Advantages of Direct Seeding?

1. Economy: The cheapest and most accessible raw material.

2. Health: Reduces the risk of transmitting diseases that accumulate during the storage of sets.

3. Quality: You control the entire process, from variety to storage conditions, and can obtain a product with specified characteristics.

Conclusion for the Gardener: First of all, look at your region. If you have a long summer and the day exceeds 15 hours—spring sowing is suitable for you. If you have a mild winter and a short but hot summer—explore the possibilities of autumn or summer sowing to obtain early production. And never forget: success is 70% dependent on the correctly chosen variety, adapted to the day length in your specific area. In the next chapter, we will analyze in detail how to choose this "ideal" variety.

2.1. The Main Criterion: Photoperiodic Response ("short-day" vs. "long-day")

As we already discussed in the first chapter, onion is a long-day plant. But within this rule, there is a huge diversity. Varieties are divided into groups depending on what day length triggers the bulbing process.

Short-day varieties: Critical day length—10–12 hours. They start forming a bulb as soon as the day becomes long enough (which in the tropics happens all year round). If such a variety is sown in the temperate zone, where the summer day lasts 16–17 hours, it will "decide" that it's time to form a bulb when the plant is still small and has not accumulated enough leaf mass. As a result, you will get a small, early-maturing bulb that also stores poorly (Nonnecke 1989; Brewster 2008). Such varieties are categorically unsuitable for northern regions.

Long-day varieties: Critical day length—14–16 hours or more. These varieties are "patient": they will grow leaves until the day becomes long enough. This gives the plant time to develop a powerful leaf apparatus, which then ensures a large bulb. These are precisely the varieties needed for regions with long summer days (northern and central regions of Russia, Canada, Northern Europe). Here, they give the maximum yield (Brewster 2008; Krug 1986).

Intermediate-day varieties: Critical day length—about 13–14 hours. They occupy the niche between the first two groups and are suitable for regions with a temperate climate, where the day does not reach extreme values (e.g., the south of the temperate zone).

Practical conclusion: When buying seeds, be sure to pay attention to the variety description. Manufacturers often indicate: "for northern regions," "for southern regions," "long-day variety," "short-day variety." If such information is not available, it is better to check with the seller or choose a variety recommended for your climatic zone.

2.2. The Second Criterion: Maturation Period (Early Ripening)

Even within the "long-day" varieties, there are differences in the rate of development. For an annual crop in conditions of a short summer, you need to choose early-ripening and mid-ripening varieties.

• Early-ripening varieties (period from emergence to lodging of leaves—80–90 days) allow you to get a harvest even in regions with cool and short summers. They produce medium-sized bulbs (50–90 g), but they are guaranteed to ripen. Examples: 'Strigunovsky', 'Bessonovsky' (Balashev and Zeman 1981).
• Mid-ripening varieties (90–110 days)—the golden mean. They produce larger bulbs (100–150 g and more), while still managing to ripen in most temperate climate regions. This is the largest group of varieties suitable for growing from seeds in one year. Examples: 'Karatalysky', 'Zolotnichok', 'Stuttgarter Riesen' (Kasynkina and Kudin 2018; Torikov and Sychev 2018).
• Late-ripening varieties (110–140 days) in conditions of a short summer may not have time to form a full-fledged bulb. They are better suited for a two-year crop (through sets) or for growing in southern regions with a long warm period. However, if you have a long and warm autumn, you can try them as well. Examples: 'Spanish 313', 'Kaba' (Balashev and Zeman 1981).

2.3. Additional Criteria: Taste, Color, and Purpose

In addition to the "technical" characteristics, it is important to consider your personal preferences and growing goals:

By taste: Varieties are divided into pungent, semi-pungent, and sweet (salad).

• Pungent varieties ('Bessonovsky', 'Tervin') contain many essential oils, they store excellently in winter (up to 6–7 months), but have a sharp, burning taste. Typical for northern regions (Balashev and Zeman 1981).
• Semi-pungent varieties ('Zolotnichok', 'Odintsovets', 'Stuttgarter Riesen')—the most popular. They combine good taste, suitability for storage (up to 4–5 months), and relatively high yield. Most modern hybrids belong to this group (Kasynkina and Kudin 2018).
• Sweet varieties ('Spanish 313', 'Exhibition')—ideal for salads. They are juicy, tender, without bitterness. But their storage life is usually low (3–4 months), so they are often eaten fresh or used for processing. Such varieties originate from southern regions and require a longer day length (Balashev and Zeman 1981).

By color of dry scales: Yellow onion (the most common) is valued on the market, as well as white (for processing) and red/purple (for salads). The choice of color is a matter of aesthetics and marketing, but remember that red and white varieties are often less storable than yellow ones.

Hybrids (F1) vs. open-pollinated varieties: Hybrids are the result of targeted breeding. They are more productive, their bulbs are very uniform in size and shape, and they are often resistant to diseases (e.g., downy mildew). However, hybrid seeds are significantly more expensive, and collecting seeds from your own harvest does not make sense (they will not retain the parental properties). For commercial growing and for those who value high quality and uniformity, hybrids are an excellent choice. For amateurs and enthusiasts who want to preserve their own varieties, it is better to use traditional varieties (Kasynkina and Kudin 2018).

2.4. Specific Variety Recommendations (Based on Data from Sources)

To make it easier for you to navigate, here are a few proven varieties recommended for annual cultivation in different conditions:

For regions with a long day and short summer (north, center):

• 'Stuttgarter Riesen'—a time-tested German variety, medium-early, semi-pungent, with large flat-round bulbs (up to 150–250 g), excellent storage. One of the most reliable for growing from seeds (Kasynkina and Kudin 2018).
• 'Zolotnichok'—mid-ripening, semi-pungent, with round golden-yellow bulbs (60–100 g). Valued for stable yield and good ripenability (Kasynkina and Kudin 2018).
• 'Odintsovets'—one of the best early-ripening varieties for the middle zone, resistant to diseases, produces a uniform harvest.

For southern regions with mild climates:

• 'Karatalysky'—mid-ripening, semi-pungent, very productive variety for irrigated lands. Excellent for summer-autumn and autumn sowings.
• 'Spanish 313'—late-ripening, sweet, with large yellow bulbs. Demanding of heat and a long growing season, therefore only suitable for the south (Balashev and Zeman 1981).

Hybrids (F1) for intensive cultivation:

• 'Tammara' F1—medium-early hybrid, semi-pungent, with large (80–100 g) uniform round bulbs, very good storage, and resistance to fusarium (Kasynkina and Kudin 2018).
• 'Exhibition' F1—a sweet salad hybrid that, with the seedling method, produces giant bulbs up to 1 kg. We mention it in our guide, but it is worth remembering: to achieve such sizes requires a very long growing season, so in regions with short summers, it is better to grow it through seedlings rather than direct sowing (Kasynkina and Kudin 2018).

2.5. Summary: How to Choose Your Variety

1. Determine your region and the prevailing summer day length.

2. Select the group of varieties by photoperiod: for the north—strictly long-day; for the south—short-day varieties are also possible.

3. Assess the length of your summer: if it's short—choose early varieties; if it's long and warm—you can choose mid- and late-ripening ones.

4. Decide what is more important to you: pungent onion for long-term storage, sweet for salads, or semi-pungent—universal.

5. Don't chase exotics: choose varieties and hybrids that have already been tested in your climatic zone (zoned). Information about this is available in the State Register of Breeding Achievements (for Russia) or in the recommendations of local agronomic services.

Remember: even the best variety will not yield a harvest if it is planted at the wrong time or if agrotechnical practices are not followed. In the next chapter, we will tell you how to properly prepare seeds for sowing to give them the best possible start.

3.1. First Step: Calibration and Culling

Before starting any treatments, make sure your seeds are of good quality. Onion seeds retain germination for 2–3 years, but it is best to use fresh (last year's) seeds or those with a guaranteed high laboratory germination rate (at least 80–85%) (Balashev and Zeman 1981).

• Visual inspection: Discard seeds that are too small, damaged, or dark. Large, well-filled seeds have more nutrient reserves and produce stronger seedlings.
• Salt test (optional): For more thorough culling, you can dip the seeds in a 3–5% solution of table salt (30–50 g of salt per 1 liter of water). Floating seeds are empty or shriveled and are removed. Those that sink to the bottom are viable. After this, they must be thoroughly rinsed in clean water (Torikov and Sychev 2018).

3.2. Disinfection: Protection from Diseases

Onion seeds can be carriers of fungal and bacterial pathogens (e.g., phomosis, downy mildew). Therefore, disinfection is a mandatory procedure.

• Heat treatment (the most reliable method): Seeds are placed in hot water at a temperature of +48…+50°C for exactly 20 minutes. It is important to maintain the temperature within this range: at lower temperatures, the effect is weak; at higher temperatures, you can "cook" the seeds. After heating, the seeds are immediately cooled in cold water for 2–3 minutes and dried until free-flowing. This method kills fungal infections on the surface and inside the seed (Kasynkina and Kudin 2018; Balashev and Zeman 1981).
• Chemical dressing: If there is no way to precisely control the water temperature, you can use approved fungicides (e.g., TMTD-based products). The treatment is carried out strictly according to the instructions. This is a simpler, but not always 100% effective, method of protection against internal infection.

3.3. Soaking and Stimulation: Giving Energy for the Start

After disinfection, you can move on to stimulating procedures. They accelerate swelling and activate enzymatic processes, reducing the time to emergence by 3–5 days.

• Simple soaking: The most accessible method is to soak the seeds in clean water at room temperature (+20…+25°C) for 12–24 hours. It is advisable to change the water 2–3 times to remove substances that inhibit germination. The seeds should only swell, not germinate. Important: before sowing, they must be dried until free-flowing, otherwise they will stick together and it will be impossible to sow them evenly (Torikov and Sychev 2018).
• Treatment with micronutrients and stimulants: Soaking in a 0.01–0.02% solution of micronutrient fertilizers (a mixture of boron, manganese, molybdenum, zinc) or in a solution of humates, succinic acid, zircon, epin for 12–18 hours significantly increases germination energy and plant resistance to adverse conditions. This is especially relevant for cold and arid regions (Torikov and Sychev 2018). Why it works: micronutrients participate in enzymatic processes, and stimulants activate the plant's defense systems at the very earliest stage.

3.4. Bubbling: Oxygen Bath for Seeds

This is a more effective, although less accessible for the amateur, method. The seeds are placed in a container with water at room temperature, and oxygen or ordinary air is passed through the water using a compressor. The process lasts 18–20 hours. Bubbling accelerates germination, increases germination, and disinfects the seeds by saturating them with oxygen (Balashev and Zeman 1981; Torikov and Sychev 2018).

For whom: for farmers and advanced gardeners who have access to a compressor.

3.5. Pelletizing: For Precision Sowing

This is an industrial technique where a coating of a mixture of peat, glue, micronutrients, and protective agents is applied to the seeds. Such seeds become large, rounded, and easy to sow one by one at a specified interval. Pelleted seeds (pellets) greatly simplify the sowing process, save seeds, and avoid thinning (Brewster 2008). However, their cost is higher, and they require stricter adherence to soil moisture after sowing, as the coating must dissolve.

For whom: for those who use precision seeders and value planting uniformity.

3.6. Brief Summary of Seed Preparation

1. Inspect and calibrate (if necessary)—remove shriveled ones.

2. Heat in water +50°C for 20 minutes or dress—this is mandatory protection against diseases.

3. Soak for 12–24 hours in water with stimulants (optional)—this will accelerate awakening.

4. Dry the seeds until free-flowing immediately before sowing.

Important: Do not soak seeds if the soil is not warm enough. At low temperatures (below +10°C), swollen seeds may rot. Sow only in warm soil.

Now your seeds are ready for sowing. In the next chapter, we will address the most exciting question: when exactly to sow them so that the onion has time to grow and mature.

4.1. Spring Sowing: The Main Strategy for the Temperate Zone

For most regions with a temperate climate (northern and central regions of Russia, Northern Europe, Canada, northern USA), spring sowing is the main and most reliable way to grow onions from seeds in one season.

When to start? As soon as the soil allows. In the middle zone of Russia, this is usually late April—the first ten days of May; in more northern regions—mid-May. The guideline is the physical maturity of the soil: it must be sufficiently loose, not stick to tools, and have a temperature at the seeding depth (2–3 cm) of no less than +5…+6°C (Balashev and Zeman 1981).

Why is it so important not to be late? Onion is a long-day plant. Bulb formation is triggered when a certain critical day length (usually 14–16 hours) is reached. If sowing is late, the plants simply will not have time to accumulate sufficient leaf mass before the onset of this "bulb-forming" photoperiod. The fewer leaves that manage to form before the start of bulb formation, the smaller the bulb will be. Experiments show that with a 2–3 week delay in sowing, the yield can decrease by 30–50% (Brewster 2008).

Optimal temperature for germination: Onion seeds begin to germinate already at +1…+2°C, but the process is fastest and most uniform at +18…+20°C (Torikov and Sychev 2018). However, you should not wait for the soil to warm up to such values—during early sowing, the seeds swell and "wait" for warmth, and seedlings appear when conditions become favorable. This gives them a head start.

An important nuance: There is a risk of falling under return frosts with early sowings. However, onion seedlings can withstand short-term frosts down to -3…-5°C, so light cold snaps are not dangerous for them (Balashev and Zeman 1981; Torikov and Sychev 2018).

4.2. Special Strategies for Southern Regions: Autumn and Summer-Autumn Sowing

In regions with mild winters and hot summers (Central Asia, Transcaucasia, southern USA, Mediterranean), spring sowing often gives low yields because the heat comes too quickly and inhibits plant growth. Other timings are more effective here.

Autumn sowing (November–December): Seeds are sown in frozen ground so that they swell but do not germinate before spring. In spring, such plants start growing very early, use winter moisture, and form a powerful root system. The harvest ripens 10–15% earlier and is often higher than with spring sowing. However, this method has a significant drawback: onions grown from autumn sowing bolt more strongly (produce flower stalks) and store worse. Therefore, its produce is sold first—fresh or for processing (Balashev and Zeman 1981; Kasynkina and Kudin 2018).

Summer-autumn sowing (August–September): In Central Asia and other warm regions, sowing in late summer is practiced. The plants manage to develop a leaf rosette before the cold weather, overwinter, and in spring quickly start growing, yielding a harvest by May–June. This method also gives high yields, but, like autumn sowing, causes increased bolting (Balashev and Zeman 1981).

For whom these methods are intended: For residents of southern regions who cannot get a bulb onion from spring sowing due to early and intense heat, and for those who want to obtain an extra-early harvest for sale.

4.3. How to Decide on Sowing Dates

1. Look at your region. If you have a long spring and a not-too-hot summer—your method is early spring sowing.

2. Do not chase ultra-early dates. You need to sow not when "it's time according to the calendar," but when the soil is physically ready (not too wet and not too cold). The optimal soil temperature for sowing is +5…+8°C at a depth of 5 cm.

3. Consider weather anomalies. If the spring is protracted and cold, do not rush—seeds can rot in cold, wet soil. Wait for a steady warming.

4. For southern regions: if you want an early harvest and are ready to sacrifice storability, try autumn or summer-autumn sowing. If you need onions for winter storage—stick with spring sowing, but choose varieties resistant to bolting and heat.

Remember: the correct sowing date is the foundation on which your entire harvest is built. A delay in sowing leads to the plants not having time to accumulate leaf mass, and the bulbs form small. In the next chapter, we will discuss how to sow onions correctly: at what distance and to what depth, so that the plants have room to grow and develop comfortably.

5.1. The Main Principle: The Denser, The Smaller

There is an inverse relationship between plant density and bulb size. The more plants per unit area, the more they compete for light, moisture, and nutrients. As a result, the bulbs form smaller, but they ripen better and store better. Sparse sowing gives large bulbs, but they may not have time to ripen and will store worse (Balashev and Zeman 1981; Brewster 2008).

Why does this happen? Onion is a long-day plant. Once the day length exceeds the critical threshold, an active outflow of nutrients from the leaves to the bulb begins. If there are many plants, each receives less light and nutrition, which speeds up this process but reduces the final size. If there are few plants, they can grow leaves for a longer time and form a larger bulb, but the ripening process may be delayed (Brewster 2008).

5.2. Choosing a Scheme Depending on the Goal

In annual cultivation, we aim to obtain a marketable bulb, not sets. Therefore, the optimal plant density for obtaining large, ripened bulbs is 70–100 plants per 1 m² (Balashev and Zeman 1981; Torikov and Sychev 2018). There are several approaches to achieve this density.

Wide-row sowing (classic variant):

This is a traditional method where the distance between rows is 45–60 cm, and between plants in the row—4–6 cm. The plant density thus reaches 70–100 plants per 1 m². This method is convenient for mechanized inter-row cultivation, but it leaves a large area of unused land, which reduces the overall yield from the bed (Balashev and Zeman 1981).

Belt (multi-row) sowing:

This is a more modern and productive method. Seeds are sown in several rows (usually 2–5) with a distance between rows of 15–25 cm, and a wide passage (50–70 cm) is left between the belts. For example, the 20+50 scheme means that two rows are spaced 20 cm apart, followed by a wide passage of 50 cm. This scheme allows for more plants per unit area while maintaining the possibility for maintenance (inter-row cultivation) and improving plant illumination (Torikov and Sychev 2018; Balashev and Zeman 1981).

Wide-band sowing:

With this method, seeds are sown in a continuous band 8–15 cm wide. Inside the band, the plants are distributed unevenly, but the overall density is high. This method gives very high yields on fertile, irrigated soils but practically excludes mechanized maintenance. Therefore, it is more often used in intensive farms in southern regions (Balashev and Zeman 1981).

5.3. Calculating the Seeding Rate

To achieve the desired plant density, you need to correctly calculate the seeding rate. It depends on seed germination, their size, and the sowing scheme you use.

For wide-row and belt sowing with manual thinning:

The seeding rate for wide-row sowing is usually 8–12 kg/ha (0.8–1.2 g/m²). For belt sowing, the rate can be increased to 14–18 kg/ha (1.4–1.8 g/m²), as some plants are removed during thinning (Balashev and Zeman 1981).

For precision sowing without thinning:

If you are using a precision seeder and high-quality, calibrated seeds with high germination (at least 92–95%), then the seeding rate can be reduced to 4–6 kg/ha (0.4–0.6 g/m²). With this technology, seeds are sown at a specified interval (usually 3–5 cm), which completely eliminates manual thinning (Brewster 2008; Torikov and Sychev 2018).

Example calculation for the home gardener:

On a standard bed 10 m long and 1 m wide, you can place 5 rows spaced 20 cm apart. If in each row you sow 1 seed every 3 cm, then one row will take 333 seeds, and the whole bed—1665 seeds. With 80% germination, you will get about 1300 plants or 130 plants per 1 m². If you want medium-sized bulbs (80–100 g), this is quite sufficient. To get larger bulbs (150 g and more), you need to reduce the density to 80–90 plants per 1 m², sowing seeds at 4–5 cm intervals.

Practical tip: If you use pelleted seeds, keep in mind that they weigh more than regular ones. Therefore, the seeding rate (in grams) is adjusted according to the manufacturer's recommendations, but in terms of the number of seeds per linear meter, they are guided by the specified distance between them (Brewster 2008).

5.4. Recommendations for Schemes for Different Conditions

• For home gardeners: For manual care and obtaining large bulbs, a scheme with wide (35–45 cm) row spacing and 5–6 cm in-row spacing is convenient. This gives 40–50 plants per linear meter, or 100–120 plants per 1 m².
• For farmers with mechanization: If you have access to cultivators, it is better to use belt schemes with alternating narrow (15–25 cm) and wide (50–70 cm) row spacings. This allows efficient use of equipment and obtaining a high yield per unit area.
• For southern regions (irrigated agriculture): Here, narrow-row (15–20 cm) and wide-band sowings are often used, which give maximum yields (up to 500–800 c/ha) with intensive agricultural technology. However, such schemes require very careful weed control and precise irrigation (Balashev and Zeman 1981).

5.5. Brief Summary of the Sowing Scheme

1. To obtain marketable bulbs of medium and large size, the optimal density is 70–100 plants per 1 m².

2. Wide-row scheme (45–60 cm between rows, 4–6 cm between plants)—the simplest and most reliable option for amateurs.

3. Belt scheme (e.g., 20+50 cm) allows increasing the yield per unit area and simplifies mechanized maintenance.

4. Precision sowing using pelleted seeds and precision seeders avoids thinning and saves seeds.

5. Do not over-densify the sowing if you want large bulbs. And do not thin too much if storability is important.

Now that you know how to properly place the seeds in the bed, it is time to understand the sowing depth. It is on this that depends whether the seedlings will emerge uniformly and whether they can break through the soil. More on this in the next chapter.

6.1. The Main Rule: Shallow, But Not Too Shallow

Onion seeds belong to small-seeded crops. Their size (usually 2–3 mm) and the peculiarity of germination (hypogeal—the cotyledon remains in the soil) dictate strict requirements for sowing depth.

Optimal depth: 1.5–2.5 cm on heavy, prone to crusting soils, and 2–3 cm on light, sandy, and sandy-loam soils (Balashev and Zeman 1981; Torikov and Sychev 2018).

Why exactly this depth? When sowing deeper than 3–4 cm, the risk increases that the seedling will not be able to bring the cotyledon to the surface. It expends all its nutrient reserves to overcome the soil layer, and as a result, the seedlings emerge weakened, with a delay, or not at all. When sowing shallower than 1 cm, the seeds may dry out in the topsoil layer, especially in dry and windy weather, and not germinate (Brewster 2008).

6.2. Why is Sowing Depth So Important?

1. Access to moisture: The topsoil layer (0–1 cm) dries out quickly even in slightly windy weather. Seeds sown at such a depth may swell but then dry out and die. At a depth of 2–3 cm, the moisture is more stable, ensuring uniform germination.

2. Strength of the seedling: Onion seeds contain a limited supply of nutrients. If the seedling has to overcome too thick a layer of soil (more than 4 cm), its strength may not be enough to emerge to the surface. As a result, the seeds produce weak, twisted seedlings or die in the soil.

3. Root system formation: When sown at the optimal depth, the root system forms in the most fertile and well-aerated soil layer. This gives the plants a good start and accelerates their development in the first weeks after emergence.

6.3. Influence of Soil Type on Sowing Depth

The sowing depth should be adjusted depending on the mechanical composition of the soil:

• Light, sandy-loam, and sandy soils: On such soils, you can sow slightly deeper (up to 3 cm), as they dry out quickly, and the seeds need a greater moisture reserve. However, it is important to remember that on sandy soils with strong wind, the top layer can be blown away, so it is recommended to compact the soil after sowing (rolling).
• Medium, loamy soils: The optimal depth is 2–2.5 cm. This is a universal recommendation for most gardeners.
• Heavy, clayey soils: On such soils, the sowing depth should be minimal—no more than 1.5 cm. Reasons: on heavy soils, when sown deeper than 2 cm, seedlings have great difficulty breaking through the dense, crust-forming layer after rain. In addition, on heavy soils, moisture is retained longer in the top layer, so shallow sowing is justified here.

6.4. Specifics for Different Sowing Methods

• Manual sowing: With manual sowing, it is easy to control the depth by sowing seeds in prepared furrows. After sowing, the furrows are carefully covered with loose soil or humus and lightly compacted.
• Sowing with a seeder: When using seeders, it is important to correctly adjust the sowing depth. Many modern seeders allow setting the depth with an accuracy of 0.5 cm. It is recommended to make a test pass before starting work and check the actual sowing depth (Brewster 2008).
• Autumn sowing: During autumn sowing (in southern regions), the sowing depth can be slightly greater (up to 3–4 cm) to prevent the seeds from freezing. In addition, a mandatory technique is mulching with humus or peat with a layer of 2–3 cm after sowing to protect the seeds from freezing and the formation of a soil crust (Balashev and Zeman 1981).

6.5. Practical Recommendations

1. For manual sowing: Make furrows 2–3 cm deep, place the seeds, cover them with loose soil or humus. If the soil is dry, be sure to water the bed by sprinkling after sowing to ensure seed-to-soil contact.

2. For seeders: Set the sowing depth to 2–2.5 cm. Before starting work, check the depth on a level area by making test passes and measuring the actual depth of seed placement.

3. Soil compaction: After sowing, be sure to roll the soil (or compact it with the back of a rake). This will ensure good contact of the seeds with the moist soil, which will accelerate germination.

4. Mulching: In dry regions or during autumn sowing, be sure to mulch the sowings with peat, humus, or compost with a 1–2 cm layer. This will protect the seeds from drying out and the formation of a soil crust.

6.6. Brief Summary of Sowing Depth

1. Optimal depth: 1.5–2.5 cm on heavy soils, 2–3 cm on light soils.

2. Do not bury seeds deeper than 3–4 cm—the seedlings will not be able to break through.

3. Do not sow shallower than 1 cm—the seeds will dry out in the topsoil layer.

4. After sowing, be sure to compact the soil—this will improve seed-to-soil contact and accelerate germination.

5. In dry weather and during autumn sowing, use mulching to retain moisture and protect against temperature fluctuations.

Now that the seeds are sown at the correct depth, it is time to think about regulating plant density. In the next chapter, we will discuss when and how to thin to get not just uniform seedlings, but large, ripened bulbs.

7.1. Why Thin Onions?

1. Increasing bulb size: When plants are crowded, they compete for light, water, and nutrients. This accelerates the onset of bulb formation (the "denser, smaller" mechanism kicks in), but the final size remains small. Thinning reduces competition, and the plants can grow leaves for a longer time, ultimately leading to larger bulbs (Balashev and Zeman 1981).

2. Improving ripening and storability: In dense plantings, plants are less illuminated and ventilated, which delays bulb maturation and increases the risk of fungal diseases. Bulbs from thinned plantings ripen better, have dense dry scales, and store longer (Brewster 2008).

3. Reducing the risk of bolting: In dense plantings, plants experience stress (including from lack of light and nutrition), which can provoke flower stalk formation (bolting) even in varieties not prone to this (Kasynkina and Kudin 2018).

Important: Thinning is not just "pulling out the extras." It is a purposeful process of forming the optimal plant density.

7.2. When to Thin?

The optimal time is the phase of 2–3 true leaves (plant height about 10–15 cm). At this point, the plants are strong enough to survive transplanting but have not yet begun to actively compete with each other. Delaying thinning leads to the plants overgrowing and starting to suppress each other, and even after removing the "extra" neighbors, they may not catch up (Torikov and Sychev 2018).

Practical tip: If you sowed very densely, you can carry out two thinnings. The first—in the phase of 1–2 true leaves, leaving 2–3 cm between plants. The second—after 2–3 weeks, when the plants reach 15–20 cm, leaving the final distance.

7.3. How to Thin Correctly?

1. Choose the weather: It is best to thin on a cloudy day or in the evening when the soil is moist. This reduces stress for the remaining plants. If the weather is dry and hot, water the bed abundantly the day before thinning.

2. Remove weak and diseased plants: Leave only the strongest, well-developed specimens with bright green leaves. Remove all twisted, weak, plants damaged by diseases or pests.

3. Do not pull, but carefully pinch out: When thinning, try not to damage the roots of neighboring plants. It is better to hold the soil with your fingers and carefully pinch out the extra plant rather than pull it out by the roots. After thinning, lightly compact the soil around the remaining plants to restore root-to-soil contact.

4. Water abundantly after thinning: This will help the remaining plants recover from stress faster and fill the vacated space.

7.4. Optimal Density for Obtaining Marketable Bulbs

It all depends on the desired size and soil type, but there are general guidelines:

• To obtain medium-sized bulbs (80–120 g): 70–100 plants per 1 m². This corresponds to a distance between plants in the row of 4–6 cm with wide-row sowing (45–60 cm between rows) (Balashev and Zeman 1981).
• To obtain large bulbs (120–150 g and more): 50–70 plants per 1 m². Distance between plants in the row—6–8 cm (Torikov and Sychev 2018).
• To obtain very large bulbs (more than 200 g) or for sweet salad varieties: 40–50 plants per 1 m². Distance—8–10 cm.

Important: On fertile, irrigated soils, you can leave a slightly denser planting (closer to 100 plants per 1 m²), as nutrient and moisture conditions allow the plants to realize their potential even with denser planting. On poor soils or in arid conditions, the density should be reduced to 60–70 plants per 1 m².

7.5. What to Do with the Pulled Plants?

They can be used as greens—this is a full-fledged "bunching onion" that can already be added to salads and soups. If you were late with thinning and the plants are already large, they can be transplanted to another place, but they will take root worse and produce smaller bulbs than those grown without transplanting.

7.6. Brief Summary of Thinning

1. Carry out in the phase of 2–3 true leaves.

2. Leave 4–8 cm between plants in the row (depending on the desired size).

3. Remove weak, diseased, and twisted plants.

4. Work in wet weather or after watering.

5. Be sure to water after thinning.

Thinning is your "tool" for managing the size and quality of the harvest. Do not spare time for this technique; it will pay off handsomely. And now—about how to care for onions at every stage of their life so that they grow healthy and strong.

8.1. Phase 1: From Sowing to Emergence (First 2–3 Weeks)

Goal: Ensure uniform and rapid emergence of seedlings.

• Watering: During this period, the moisture of the topsoil layer is critically important. If the weather is dry and windy after sowing, regular watering is necessary (preferably by sprinkling, but carefully, so as not to wash away the soil). Before emergence, the soil should not dry out deeper than 1 cm.
• Crust control: If a dense crust has formed on the surface after rain, it needs to be broken up with light loosening (you can use a rake with frequent teeth), otherwise, the seedlings will not be able to break through. This must be done very carefully to avoid damaging the yet-unemerged seeds.
• Weed control: During this period, weeds are especially dangerous because they quickly outgrow the slowly developing onion seedlings. Hand weed, and for larger areas, use pre-emergence herbicides (strictly according to instructions). However, for home gardens, I recommend manual labor or the use of mulching materials.

Why this is important: The root system of the onion develops slowly, and in the first weeks, it is very vulnerable. Any delay in growth during this period can lead to the onion not having time to grow enough leaves before bulbing begins (Balashev and Zeman 1981; Brewster 2008).

8.2. Phase 2: Leaf Growth (From Emergence to the Beginning of Bulb Formation)—4–8 Weeks

Goal: Maximize healthy leaf mass.

• Watering: During this period, the onion actively consumes moisture. The soil should be constantly moist (not wet) to a depth of 15–20 cm. Optimal moisture is about 80% of full field capacity. Water regularly (1–2 times a week), especially in hot weather. Lack of moisture during this period strongly retards leaf growth and reduces the future harvest (Balashev and Zeman 1981).
• Loosening and weeding: After each watering or rain, as soon as the soil dries, loosen the row spacings. This breaks the crust and improves root aeration. At the same time, remove weeds—they are the main competitors of onions during this period.
• Fertilization: The first feeding is carried out 2–3 weeks after emergence, when 3–4 true leaves have formed. Apply nitrogen fertilizers (e.g., ammonium nitrate, urea) at the rate of 10–15 g per 1 m² (or 50–70 kg/ha in terms of active ingredient). Nitrogen stimulates leaf growth—the more leaves, the larger the bulb will be. It is better to apply fertilizer after watering or combine it with it to avoid root burn (Torikov and Sychev 2018).
• Thinning: It is in this phase (3–5 leaves) that the main thinning is carried out, as we discussed in chapter 7.

Important: Do not overdo it with nitrogen at the end of this phase. Excess nitrogen delays bulb formation and worsens storability. The transition to potassium-phosphorus nutrition begins from the moment of bulb initiation.

8.3. Phase 3: Beginning of Bulb Formation (Usually Coincides with the Increase in Day Length to the Critical Length, Mid–Late June in the Temperate Zone)

Goal: Redirect nutrition from leaves to bulb formation.

• Watering: The need for moisture remains high, but watering should be done less frequently (once every 7–10 days), but more abundantly (to wet the soil to a depth of 30–40 cm). It is important not to allow drying out, otherwise bulb growth may stop.
• Fertilization: During this period, phosphorus-potassium fertilizers are applied (e.g., superphosphate + potassium salt or monopotassium phosphate) at the rate of 15–20 g of phosphorus and 15–20 g of potassium per 1 m². This accelerates bulb ripening and improves their storability. Nitrogen in top dressings at this stage is excluded or the dose is greatly reduced (no more than 5 g/m²) so as not to provoke excessive leaf growth (Balashev and Zeman 1981).
• Disease and pest control: During this period, diseases (downy mildew) and pests (onion fly, thrips) actively develop. Carefully inspect the plantings. At the first signs of disease, treat the plants with approved fungicides. Against pests, use insecticides (according to instructions), but remember that treatment must be stopped 20–30 days before harvest (Torikov and Sychev 2018).

8.4. Phase 4: Bulb Filling and Maturation (July–August)

Goal: Ensure maturation and the formation of quality dry scales.

• Watering: About 3–4 weeks before harvest (when the leaves begin to yellow and lodge), watering is completely stopped. Excess moisture during this period delays ripening, worsens storability, and provokes the growth of new roots and secondary shoots (Balashev and Zeman 1981).
• Accelerating ripening (optional): If the onion does not want to lodge, you can carefully bend (press) the leaves to the ground or slightly cut the roots with a spade at a depth of 5–7 cm. This accelerates the outflow of nutrients from the leaves to the bulb and promotes faster ripening.
• Disease protection: At this time, it is important to prevent infection with neck rot (Botrytis). Regularly inspect the bulbs, especially if the weather is wet. If signs of rot are found, remove the diseased plants.

Sign of readiness for harvest: Mass lodging and yellowing of leaves, dry, rustling neck of the bulb, easily separating dry scales. This usually occurs 80–120 days after emergence, depending on the variety (Kasynkina and Kudin 2018).

8.5. Brief Summary of Care by Phases

Now that you know how to care for onions at each stage, it is time to talk about nutrition—what elements and in what doses the plant needs for maximum yield. More on this in the next chapter.

9.1. What Does Onion Like? Main Nutrients

To form a good harvest, onions need three main elements: nitrogen (N), phosphorus (P), and potassium (K). But their ratio and role change at different stages of growth.

• Nitrogen (N): This is the main "building material" for leaves. Nitrogen stimulates the growth of green mass, which is especially important in the first 6–8 weeks after emergence. The more leaves the plant manages to grow before the start of bulb formation, the larger it will be. However, excess nitrogen during bulb formation delays its maturation, worsens storability, and makes the onion more susceptible to diseases (Brewster 2008; Torikov and Sychev 2018).
• Phosphorus (P): This element is responsible for the development of the root system, growth energy, and bulb formation. Phosphorus is especially important during the transition from leaf growth to the beginning of bulb initiation. It accelerates maturation and improves the quality of bulbs (density, storability). In addition, phosphorus increases the resistance of plants to adverse conditions (drought, cold) (Balashev and Zeman 1981).
• Potassium (K): Potassium is the "quality element." It improves taste, increases sugar content, strengthens cell walls, making bulbs denser and more resistant to mechanical damage. Potassium also increases resistance to diseases and improves storability. Potassium is especially important in the second half of the growing season when the bulb is forming (Torikov and Sychev 2018; Kasynkina and Kudin 2018).

9.2. Soil Preparation: The Foundation

The key to success is proper soil preparation even before sowing. Onion prefers loose, fertile, well-drained soils with a neutral or slightly alkaline reaction (pH 6.5–7.5). On acidic soils, it grows poorly, gets sick more often, and the bulbs store worse (Balashev and Zeman 1981).

What to add before sowing (basic fertilizer):

1. Organic matter: Fresh manure should not be applied to onions—it causes rapid leaf growth at the expense of the bulb, delays maturation, and provokes diseases. But you can use well-rotted humus or compost at the rate of 20–30 t/ha (2–3 kg/m²) for autumn or spring plowing (Balashev and Zeman 1981; Torikov and Sychev 2018).

2. Mineral fertilizers: The optimal dose for an annual crop: nitrogen (N)—60–90 kg/ha, phosphorus (P₂O₅)—60–90 kg/ha, potassium (K₂O)—60–90 kg/ha of active ingredient. This is approximately 6–9 g/m² of each element in pure form. In terms of specific fertilizers: ammonium nitrate (34% N)—20–30 g/m², double superphosphate (46% P₂O₅)—15–20 g/m², potassium salt (40% K₂O)—15–20 g/m² (Balashev and Zeman 1981; Kasynkina and Kudin 2018).

3. Application method: Phosphorus and potassium are best applied during autumn or spring plowing so that they are evenly distributed in the root zone. Nitrogen fertilizers (especially nitrate forms) are applied immediately before sowing or in top dressings, as they are easily leached from the soil.

Important: Do not exceed the recommended doses! Onion is very sensitive to high concentrations of salts in the soil. Excess fertilizer can cause root burn, growth retardation, and even plant death (Brewster 2008).

9.3. Fertilization Schedule During the Season

In annual cultivation, onions are very responsive to top dressings, especially in the early stages. But it is important to apply them at the right time and with the correct composition.

First feeding (phase of 2–3 true leaves, 2–3 weeks after emergence):

• Composition: Nitrogen fertilizer. Apply ammonium nitrate or urea at the rate of 10–15 g/m² (or 50–70 kg/ha in terms of active ingredient).
• Purpose: To stimulate leaf growth so that the plants build up as much green mass as possible before the onset of long days and the beginning of bulb formation. This is the most important stage for obtaining a large harvest.
• Method: It is best to apply in dissolved form together with watering or immediately after it, so that the fertilizer reaches the roots faster.

Second feeding (phase of 4–5 true leaves, about 3–4 weeks after the first):

• Composition: Balanced NPK fertilization. You can use nitroammophoska (16:16:16) or complex fertilizers with a predominance of phosphorus and potassium.
• Purpose: To support leaf growth and simultaneously begin preparing for bulb formation.
• Dose: 15–20 g/m² of complex fertilizer.

Third feeding (at the beginning of bulb formation, when the day begins to lengthen and the first signs of neck thickening appear):

• Composition: Phosphorus-potassium fertilization. Apply superphosphate + potassium salt (or monopotassium phosphate) at the rate of 15–20 g of phosphorus and 15–20 g of potassium per 1 m². Nitrogen in this feeding is excluded or given at a minimum dose (no more than 5 g/m²).
• Purpose: To switch nutrition to bulb formation. Phosphorus and potassium accelerate maturation, increase density, and improve bulb storability.
• Method: Feeding can be done in dry form (incorporating into row spacings) or in solution. After application, be sure to water.

9.4. Water Regime and Nutrition: An Inseparable Link

Onion nutrition is impossible without proper watering. Fertilizers are absorbed only in dissolved form. Therefore, top dressings should always be applied to moist soil or combined with watering.

• During the leaf growth period: Abundant watering (1–2 times a week) combined with nitrogen fertilizing gives the maximum effect.
• During the bulb formation period: Watering is reduced but not completely stopped. Top dressings are applied in solutions with a lower concentration but more frequently (e.g., every 10–14 days). This allows maintaining a steady supply of nutrients without the risk of overfeeding the plants.

9.5. Micronutrients: Little Helpers

In addition to the main elements (NPK), onions need micronutrients. Especially important are:

• Boron (B): Participates in carbohydrate metabolism, improves taste, and increases sugar content. With a boron deficiency, bulbs become loose and store worse. Applied in the form of boric acid (0.01–0.02% solution) on the leaves or with watering.
• Manganese (Mn) and zinc (Zn): Participate in photosynthesis and enzymatic processes. Increase resistance to diseases. Applied in chelated form (readily available) (Torikov and Sychev 2018).

Method of application: Micronutrients are best applied foliarly (on the leaves) during the phase of active leaf growth, when the plants are most receptive.

9.6. Table: Approximate Fertilizer Schedule for Annual Onions

9.7. What Not to Do: Common Mistakes

1. Excess nitrogen at the end of the season: This is the most common mistake. Excess nitrogen delays maturation, bulbs become loose, with thick necks, store poorly, and germinate quickly. Remember: nitrogen is for leaves, phosphorus and potassium are for the bulb.

2. Applying fresh manure: This provokes rapid leaf growth, delays maturation, and contributes to the development of fungal diseases. Use only well-rotted compost or humus.

3. Lack of phosphorus: With a phosphorus deficiency, bulbs form small, with thin dry scales, and store poorly. Make sure you have applied sufficient phosphorus fertilizers.

4. Uneven application: If fertilizers are distributed unevenly, some plants will be overfed, and others starved. This leads to uneven maturation and a reduction in overall yield. Apply fertilizers evenly across the entire area.

Remember: Proper nutrition is not only "what" you apply but also "when" you do it. Follow the fertilization schedule, take into account the phases of onion development, and it will surely thank you with a large, healthy, and tasty harvest.

Now that you know how to feed onions at each stage, it is time to talk about potential risks and problems you may encounter when growing onions from seeds in one season and how to avoid them. More on this in the final chapter.

10.1. Bolting (Flower Stalk Formation)

This is one of the most common problems when growing onions from seeds. Instead of forming a large bulb, the plant throws out a flower stalk. Such bulbs become unsuitable for long-term storage, and their commercial quality sharply decreases.

Main reasons:

1. Incorrect variety selection: Using varieties not adapted to your region. For example, sowing southern varieties (short-day) in northern regions or, conversely, northern varieties (long-day) in the south. This disrupts the photoperiodic response and provokes bolting (Balashev and Zeman 1981; Brewster 2008).

2. Unfavorable seed storage conditions or exposure of seedlings to low temperatures: Onion is a biennial plant. To transition to the generative phase (flowering), it requires a period of vernalization—exposure to low positive temperatures (from +2 to +15°C) on plants that have reached a certain size. If, in early spring after emergence, a prolonged cold spell sets in, the plants may undergo vernalization and start bolting (Brewster 2008).

3. Stressful conditions: Drought, waterlogging, lack of nutrition, pest damage—all these can provoke bolting as a defensive reaction (Kasynkina and Kudin 2018).

How to prevent:

• Choose zoned varieties adapted to the day length in your region. For northern regions—only long-day varieties. For southern ones—you can use intermediate-day varieties or locally bred ones.
• Do not allow prolonged cold spells at early stages. In case of frost threat, use covering material.
• Provide balanced nutrition, especially nitrogen and potassium, so that the plants are strong and resistant to stress.
• Observe sowing dates: Too early sowing (when the soil is still cold) increases the risk of vernalization.

What to do if stalks have already appeared? They must be immediately broken out (snapped off) as close to the base as possible. This will not save the bulb for long-term storage but will allow it to increase slightly in size. Such bulbs should be used first—fresh or for processing (Balashev and Zeman 1981).

10.2. Unformed Bulb (""Thick Neck"")

A problem where, instead of a rounded bulb, a thickened neck is formed, and the bulb itself is either very small or completely absent. This often happens when the onion does not have time to complete its development cycle.

Reasons:

1. Too late sowing: The plants do not have time to grow sufficient leaf mass before the onset of long days, and the bulb forms small, while the neck remains thick and juicy (Brewster 2008).

2. Excess nitrogen at the end of the season: Nitrogen stimulates leaf growth, delaying bulb formation. As a result, the neck does not dry out, and the bulb does not mature (Balashev and Zeman 1981).

3. Lack of moisture during the bulb formation period: If there is a severe drought in July (in the temperate zone), bulb formation may stop, and it will remain small and immature.

4. Excessive plant density: In dense plantings, plants compete for light, and bulbs form small, while the neck thickens (Kasynkina and Kudin 2018).

How to prevent:

• Sow onions at the earliest possible dates, as soon as the soil allows.
• Do not overuse nitrogen fertilizers in the second half of the growing season. Switch to phosphorus-potassium fertilizing.
• Ensure regular watering, especially during the bulb formation period. The soil should not dry out deeper than 15–20 cm.
• Thin the plantings in a timely manner, leaving the optimal distance between plants (4–6 cm for medium bulbs, 6–8 cm for large ones).

What to do? If the onion does not ripen, you can try to speed up the process: slightly cut the roots (at a depth of 5–7 cm) or bend the leaves to the ground to block the outflow of nutrients to the leaves and direct them to the bulb (Balashev and Zeman 1981).

10.3. Diseases and Pests

Onions, like other crops, are susceptible to diseases and pest attacks. The most common problems:

Downy mildew: A fungal disease that manifests as a grayish-purple coating on the leaves. It is especially active in damp and cool weather. Leaves turn yellow and die, which reduces yield and impairs storability.

Prevention: Crop rotation (return onions to the same place no earlier than after 3–4 years). Seed treatment before sowing (dressing, heating). At the first signs of the disease—treatment with approved fungicides (e.g., 1% Bordeaux mixture, copper-based preparations). Repeated treatments at intervals of 7–10 days (Torikov and Sychev 2018; Kasynkina and Kudin 2018).

Onion fly: A dangerous pest whose larvae eat the inside of the bulb and the bases of the leaves. Plants turn yellow and die.

Prevention: Deep loosening of row spacings, use of traps, dusting the soil with ash or tobacco dust. In case of mass appearance—treatment with insecticides (Balashev and Zeman 1981).

Onion thrips: A small insect that sucks sap from the leaves, causing discoloration and deformation.

Prevention: Weed control, crop rotation. If they appear—treatment with insecticides (Kasynkina and Kudin 2018).

Neck rot (Botrytis): A fungal disease that manifests during storage. Affects the neck of the bulb, causing it to soften and rot.

Prevention: Adherence to harvest dates (do not allow overripening), thorough drying before storage, maintaining optimal conditions in the storage facility (temperature 0…+1°C, humidity 65–70%) (Kasynkina and Kudin 2018).

Important: When using chemical plant protection products, strictly follow the instructions and waiting periods (the period between the last treatment and harvest). For amateurs, I recommend using biological preparations or folk remedies (ash, tobacco dust, soap solution).

10.4. Competition with Weeds

Onions are very poor competitors in the fight against weeds, especially in the first 6–8 weeks after emergence, when they grow slowly. Weeds can completely choke the onions, depriving them of light, moisture, and nutrients.

How to prevent:

• Thorough soil preparation: Destroy weeds before sowing, especially perennials (couch grass, sow thistle).
• Mulching: Use organic mulch (peat, humus, straw) or agrotextile. Mulch suppresses weed growth, retains moisture, and improves soil structure.
• Regular weeding: Hand weed, especially in the early stages. Be careful not to damage the onion roots.
• Herbicides: For larger areas, you can use approved herbicides (e.g., based on pendimethalin or glyphosate), but strictly according to the instructions and with all precautions (Balashev and Zeman 1981).

10.5. Unfavorable Weather Conditions

Heat, drought, prolonged rains, hail—all these factors can significantly reduce the yield.

• Drought: During prolonged drought, it is necessary to organize regular watering. It is better to water less often but abundantly (so that water penetrates to a depth of 20–30 cm) than often and little by little (this provokes the growth of superficial roots).
• Prolonged rains: With excess moisture, the risk of fungal diseases (downy mildew, neck rot) increases. Ensure good drainage, do not allow water stagnation. If necessary, treat with fungicides.
• Hail: Damages leaves, which reduces photosynthesis and yield. In case of severe damage, you can carry out foliar feeding with complex fertilizers to help the plants recover faster.

10.6. Storage Problems

Even if you have grown an excellent harvest, you can lose it with improper storage.

• Main problems: Rot (neck rot, bacterial rot), germination, drying out.
• Storage conditions: Onions store best at a temperature of 0…+1°C and air humidity of 65–70%. At higher temperatures, it begins to germinate; at lower temperatures, it freezes. With high humidity, rot develops.
• Preparation for storage: Before storing, the onion must be well dried (for 7–10 days at a temperature of +25…+30°C). Remove all damaged and diseased bulbs. Store onions in boxes, nets, or braids, ensuring good ventilation (Kasynkina and Kudin 2018).

10.7. Brief Summary: Main Risks and Their Prevention

10.8. Final Conclusion

Growing onions from seeds in one season is a completely achievable task, but it requires attention and knowledge. Success is made up of many factors: the right variety, timely sowing, proper thinning, balanced nutrition, and, of course, prevention of diseases and pests. If you follow the recommendations in this article and carefully observe your plants, you can avoid most problems and get an excellent harvest of large, healthy, storable onions. Remember: knowledge is your main tool in the garden!

This concludes our guide. I hope this information helps you grow a great harvest of onions from seeds in one season. Good luck in your garden beds!