Plant the onions is an essential step to obtaining an abundant and high-quality harvest. Mastering the different techniques, from choosing the variety to the harvestThis ensures healthy bulb growth and prevents common problems. This article offers a complete tutorial to guide gardeners, whether beginners or experienced, through every stage of cultivation. You'll discover how to prepare the soil, sow or plant your onions, maintain your rows, combat diseases and pests, and store the bulbs after harvest to extend their shelf life.
Table of contents
Choosing the variety for planting onions
Varieties adapted to the French climate
To successfully grow onions, it is important to select Varieties Adapted to local climatic conditions, onions tolerate temperate climates well and require a moderate period of cold to properly form their bulbs. It is advisable to choose early varieties if you want a quick harvest, or late varieties if you want to store the bulbs for longer.
Selection criteria
When choosing a variety, consider the growing season, bulb size, and disease resistance. Early varieties are ideal for quick harvests but produce smaller bulbs. Late varieties offer larger bulbs and are often more resistant to storage and disease. It's also advisable to consider your garden's soil type and sun exposure to optimize growth.
Where to plant onions
Ideal location and exposure
Planting onions requires a sunny location with at least 6 to 8 hours of sun per day to develop firm, sweet bulbs. Avoid shady areas or planting too close to large trees, which can retain moisture or compete with the roots. A light breeze is beneficial to prevent waterlogging and reduce the risk of fungal diseases.
Soil type and drainage
The soil should be light, well-drained, and rich in organic matter. Heavy or clay soils can be lightened with sand or well-rotted compost to improve texture and drainage. Moist but not waterlogged soil promotes bulb growth without causing rot.
Crop associations and rotation
Avoid planting onions after other alliums (garlic, leekPlant onions near carrots, beets, lettuce, or strawberries, which can promote their growth and repel certain insects. A 3- to 4-year crop rotation is recommended to prevent soil depletion and pest infestations.
Row spacing and arrangement
It is advisable to plant onions in rows spaced 25 to 30 cm apart, with 10 to 15 cm between each plant depending on the expected size of the bulbs. Good spacing ensures sufficient air circulation, facilitates maintenance, and reduces competition for water and nutrients. For very early varieties or for dense plantings, 8 to 10 cm between plants may be sufficient, but this requires careful planning. spray and careful clarification.
Preparing the soil for planting onions
Soil analysis and amendment
Before planting onions, it is essential to check the soil pH, which should ideally be between 6 and 7. Soils that are too acidic can be corrected with lime at a rate of 50 to 100 g/m², while soils poor in organic matter benefit from the addition of mature compost or well-rotted manure (2 to 3 kg/m²). These amendments improve soil structure, promote water retention, and provide essential nutrients for bulb development.
Ground work
The soil should be deeply dug or tilled to a depth of 20 to 25 cm to loosen clods and facilitate root growth. Remove any stones and remaining roots that could hinder the bulbs' expansion. Raking or rototilling will create a fine, homogeneous, and well-aerated soil, ideal for sowing or planting bulblets.
Base fertilization
Before planting onions, incorporate a balanced fertilizer rich in potassium and phosphorus, but moderate in nitrogen to prevent excessive foliage growth at the expense of bulb development. For example, 40 to 50 g/m² of a 5-10-15 fertilizer can be mixed into the soil. Potassium promotes bulb formation and firmness, while phosphorus stimulates root development.
Disease prevention
To limit the risk of disease, it is recommended to weed mechanically or manually before planting and to avoid reusing contaminated tools. A light mulch can be prepared to retain moisture without causing waterlogging, thus reducing the development of fungi or rot.
Sowing and planting for planting onions
Sowing in the nursery
Sowing is a common method for controlling germination and obtaining vigorous seedlings. Sow the seeds ofAllium cepa Sow the seeds in trays or pots filled with a light mixture of potting soil and sand. Space the seeds 1 to 2 cm apart and cover them lightly with about 0,5 cm of soil. Keep the substrate moist and place in a bright location at 15-20°C. The seedlings will be ready to transplant after 6 to 8 weeks, when they have 3 to 4 leaves and are about 3 to 4 mm in diameter.
Planting bulbils or young plants
Planting bulbils or young plants Growing from seed is faster than direct sowing in open ground. Plant the bulbils ofAllium cepa at a depth of 2 to 3 cm, spaced 10 to 15 cm apart in rows, which are themselves 25 to 30 cm apart. Young plants should be placed at the same depth as they grew in the nursery to avoid stress and promote rapid establishment.
Post-planting care
After transplanting or planting, water moderately to keep the soil moist but not waterlogged. A light mulch helps suppress weed growth and retain moisture. Monitor the plants' establishment during the first few days and thin them out if necessary to maintain the recommended spacing, ensuring well-formed bulbs.
Maintenance for planting onions
Watering and humidity
Growing onions requires consistently moist soil, especially during bulb formation. Water moderately, about 5 to 10 mm per week depending on rainfall, to prevent drying out without causing waterlogging, which promotes rot. Using a light mulch helps retain moisture, limit evaporation, and reduce weed growth.
Lightening and ventilation
To allow the bulbs to develop properly, thin the plants if necessary, removing the smallest or those that are too close together to maintain a spacing of 10 to 15 cm. This practice improves air circulation between the plants, reduces the risk of disease, and promotes bulbs of a uniform size.
Weed control and protection
Regular weeding, whether by hand or machine, is essential to prevent weeds from competing for water and nutrients. Avoid digging too deeply near the roots to prevent damaging them. To limit fungal diseases, aerate the rows by removing or cutting back dead leaves and spacing the plants properly.
Monitoring and adjustments
Regularly inspect the plants for any signs of stress, disease, or pest infestation. Adjust watering according to weather conditions and apply a light organic fertilizer if growth appears stunted. Consistent care throughout the season will ensure a harvest of healthy, high-quality bulbs.
Prevention and treatment of diseases when planting onions
Common diseases
Onions are susceptible to several common diseases such as mildewWhite rot and rust are common diseases. These diseases appear mainly in damp soil or when plants are planted at high density. Good air circulation and adequate plant spacing help to limit their spread.
Natural prevention methods
To prevent disease, practice crop rotation every 3 to 4 years and avoid replanting onions or other alliums in the same spot. Use a light mulch to maintain soil drainage and reduce splashing, which can spread fungi. Water at the base of the plants rather than above them to limit moisture on the foliage.
Natural treatments
If diseases appear, opt for 100% natural treatments: spray with horsetail manure, nettle manure, or garlic infusion diluted to 10-15% in water. Immediately remove any diseased leaves or bulbs to prevent contamination of neighboring plants. Maintaining healthy, well-balanced soil is the best way to limit infections throughout the entire plot.
Pest control during onion planting
Common Insects and Pests
Onions can be attacked by several pests, including the onion fly (old delia), thrips, and nematodes. The fly lays its eggs at the base of the plants, and the larvae burrow into the bulbs, while the thrips suck the sap from the leaves, causing yellowing and stunted growth. Regular monitoring allows for the early detection of these infestations.
Natural prevention methods
To limit attacks, install insect netting or lightweight netting over your rows during egg-laying periods. Plant repellent companion crops such as carrots, lettuce, or thyme, which deter certain pests. bugsRespect crop rotation and avoid planting successive alliums in the same place to reduce the proliferation of pests.
Natural and mechanical treatments
If infestations appear, manually remove any visible insects and severely affected leaves. Sprays of tansy manure or rhubarb decoction can repel some insects. Finally, watering at the base of the plant and mulching help limit excessive moisture, which encourages pest development.
Harvesting and storing onions
Signs of ripeness for harvest
Onions are ready to harvest when the leaves turn yellow and begin to fall over naturally. The bulbs should be firm to the touch and have reached the expected size for the cultivar. Waiting until the leaves have completely fallen allows for better storage, but the bulbs should not be left in the ground too long to avoid rot.
Harvesting techniques
Carefully lift the onions with a garden fork, taking care not to damage the bulbs. Shake off the soil without rubbing the bulbs to avoid damaging their protective skin. Avoid harvesting in damp soil to reduce the risk of rot and disease.
Drying and storage
After harvesting, let the onions air dry in a dry, shady, and well-ventilated place for 1 to 2 weeks. Once the leaves and roots are completely dry, you can cut the stems 2 to 3 cm from the bulb. Store the onions in ventilated crates, nets, or hanging in bunches in a cool, dry, and well-ventilated area to prolong their shelf life.
Post-harvest maintenance of onions
Cleaning and sorting the bulbs
After drying, carefully remove any remaining soil without damaging the outer skin of the bulbs. Sort the onions to separate those that are perfect, those that are slightly damaged, and those showing signs of rot. Damaged bulbs should be eaten quickly to prevent the spread of disease to the others.
Long-term storage
For optimal storage, keep onions in a cool (10-15°C), dry, and well-ventilated place. Avoid airtight plastic bags, which trap moisture and promote rotting. Mesh crates, baskets, or hanging nets are ideal for allowing air to circulate around the bulbs.
Prevention of re-germination and diseases
Check your onions regularly and remove any bulbs that show signs of sprouting or mold. Storing onions away from direct sunlight helps limit regrowth. Maintaining a dry, well-ventilated environment remains the best way to extend their shelf life and keep the bulbs healthy for several months.
Conclusion
Planting onions requires a little preparation and attention, but the effort is richly rewarded with healthy and flavorful bulbs. By choosing the right variety, carefully preparing the soil, and following good practices for sowing, care, and harvesting, a bountiful yield is possible. Disease prevention and pest control using natural methods ensure the crop's longevity. Finally, proper storage allows onions to be preserved for several months. With consistency and careful observation, every gardener can easily achieve a successful harvest.
FAQ
When to plant onions for optimal harvest?
The best time to plant onions depends on the variety and the region. Generally, early sowings are done in February-March under cover, while sets can be planted in March-April outdoors. Respect the phases of the moonAvoiding periods of frost and choosing well-prepared soil allows for good recovery and proper bulb formation.
What varieties of onions should be planted in France?
The most commonly cultivated variety is Allium cepaDepending on the type you want, you can choose cultivars. , yellow or whitesEach has different growth cycles. The choice should be made according to the harvest period and the desired storage time.
How to prepare the soil before planting onions?
The soil should be light, well-drained, and rich in organic matter. Adding mature compost or well-rotted manure is advisable to improve fertility. Deep digging and the removal of stones and roots promote root growth and bulb formation.
What are the main pests to watch out for when planting onions?
Onions can be attacked by the onion fly (old delia), thrips, or nematodes. Damage appears on the leaves or bulbs and can slow growth. Regular monitoring and natural methods such as insect netting and companion plants help to limit these infestations.
How to store onions after harvesting?
After harvesting, the bulbs should be air-dried in a dry, well-ventilated area. Once the leaves and roots are completely dry, cut them and store the onions in ventilated crates or hanging them in nets. Maintaining a cool, dry, and well-ventilated environment prolongs their shelf life and prevents re-sprouting.
