Planting a sprouted onion This is a simple way to make use of a bulb that's starting to sprout in the kitchen. Instead of throwing it away, it can be planted in the garden or in a pot to produce new onions or shoots. This method, accessible to beginner gardeners, requires little equipment and adapts to different soil types. By following a few essential steps, such as choosing the right location, preparing the soil, and regular maintenance, it becomes possible to obtain a satisfying harvest while reducing food waste and enjoying an easy-to-manage crop.
Table of contents
Choosing the right variety for planting a sprouted onion
Suitable yellow onion varieties
yellow onions These onions are among the most widely cultivated in French vegetable gardens due to their hardiness and good adaptation to temperate climates. When a bulb begins to sprout, it can be replanted to produce several shoots or develop into a new bulb if growing conditions are favorable. Among the common varieties, the 'Yellow Straw' onion from Vertus is known for its productivity and good storage qualities, with well-formed and uniform bulbs. The Sturon onion is also widely cultivated for its resistance and uniform growth, while the Mulhouse yellow onion is appreciated in cooler regions for its good adaptation to moderate temperatures. For replanting, it is important to choose a firm bulb, without soft spots or signs of rot, with green shoots measuring approximately 1 to 5 cm.
Suitable red onion varieties
red onions They can also be replanted when they begin to sprout, especially if they are still firm and healthy. They thrive particularly well in light, well-drained soils in full sun. The Brunswick red onion is a traditional variety that forms fairly large bulbs and tolerates a range of growing conditions. The Florence red onion, also called the Florence long onion, produces elongated bulbs and is well-suited to spring or early summer planting. When a sprouted red onion is replanted, it can produce several stems from the same bulb, which can result in several smaller bulbs if each shoot has sufficient space, generally between 10 and 15 cm between plants.
Suitable white onion varieties
white onions These varieties are distinguished by their rapid growth and often shorter growing cycle than yellow or red onions. Once they begin to sprout, they can be transplanted to produce new plants or young onions within a few weeks. The white Paris onion is one of the most widely cultivated varieties for early harvests, as it develops quickly in loose, well-enriched soil. The very early white Vaugirard onion is also prized for its rapid growth and ability to produce bulbs in a short time. To encourage successful establishment, it is recommended to plant the bulbs in soil that has been worked to a depth of about 15 to 20 cm to facilitate root development and the growth of new shoots.
Can you plant a commercially grown sprouted onion?
A commercially sprouted onion can be replanted in the garden or in a pot, provided it is still firm and shows no signs of disease. Some bulbs intended for sale may have been treated to slow germination, but if a sprout appears nonetheless, planting is generally still possible. Before planting, it is advisable to examine the bulb and check that the sprouts are vigorous and bright green. If several shoots are present, the bulb can be divided into several segments, keeping part of the root base on each portion. This allows you to obtain several plants capable of taking root and producing new leaves.
Where to plant a sprouted onion in the garden or in a pot
Ideal location for planting a sprouted onion
Onions are plants that require plenty of light to thrive. For consistent growth, it's advisable to choose a location that receives at least 6 to 8 hours of sunlight per day. A south- or southwest-facing location is generally ideal, as it allows the soil to warm up quickly in spring. Good air circulation is also important to limit excessive humidity around the foliage, which can reduce the risk of fungal diseases such as those caused by fungi of the genus Botrytis.
Climate and planting period vary by region
Planting sprouted onions depends largely on the local climate and time of year. In mild climates, planting can begin as early as late winter, often between February and March. In cooler regions, it is best to wait until the risk of severe frost has passed, usually between March and April. Onions tolerate relatively low temperatures, but active growth occurs primarily when the soil temperature is above approximately 10°C (50°F).
Planting a sprouted onion directly in the ground
Planting directly in the ground is the most common method in the vegetable garden. It is best to choose a well-drained plot to avoid water pooling around the bulb, which could cause rot. The soil should be loosened to a depth of about 20 cm to facilitate root development. The sprouted bulb is then placed so that its base is slightly buried, while the top remains close to the soil surface.
Planting a sprouted onion in a pot or container
Growing bulbs in pots or containers is an attractive alternative when garden space is limited. A container at least 20 to 25 cm deep is recommended to allow the roots to develop properly. The substrate should be light and well-draining, for example, a mixture of potting soil and horticultural sand. The sprouted bulb is placed in the pot with sufficient spacing if several plants are grown together, generally 10 to 12 cm between each bulb, to limit competition between the roots.
Preparing the soil before planting a sprouted onion
Ideal soil type for planting a sprouted onion
Onions thrive best in light, loose, and well-drained soil, which allows the roots to spread easily and prevents moisture from accumulating around the bulb. Sandy or loamy-sandy soils are particularly suitable, as they promote aeration and limit the risk of rot. A pH between 6 and 7 is generally considered optimal for onion cultivation. Soil that is too compact or poorly drained can slow growth and encourage the development of fungal diseases such as Fusarium ou Sclerotium cepivorum.
Improving heavy or clay soil
In clay or compacted soil, it is necessary to improve the structure before planting. Incorporating coarse sand, mature compost, or well-decomposed organic matter helps to lighten the soil and improve drainage. This work should be carried out to a depth of approximately 20 to 25 cm to create a growing layer conducive to root development. It is also helpful to create slight mounds or raised beds 5 to 10 cm high to facilitate water runoff during heavy rain.
Amend poor soil before planting
If the soil is nutrient-poor, a moderate application of well-rotted compost can be made before planting. Approximately 2 to 3 kg of compost per square meter is generally sufficient to improve fertility without causing nitrogen excess. Onions do not tolerate fresh manure applications well, as these can encourage excessive foliage growth at the expense of the bulb. Therefore, it is preferable to use well-rotted organic amendments incorporated into the soil several weeks before planting.
Soil preparation and leveling before planting
Before planting, the soil must be carefully prepared to obtain a fine, even surface. Clods should be broken up and stones removed to avoid hindering bulb development. A pass with a rake will level the surface and prepare rows spaced approximately 25 to 30 cm apart. This preparation facilitates planting the sprouted bulbs and ensures good spacing of the plants, promoting their growth and simplifying maintenance during cultivation.
Methods for planting a sprouted onion
Plant a sprouted onion directly in the ground
To plant a sprouted onion in the ground, start by digging a small hole 2 to 3 cm deep and placing the bulb inside. The base of the bulb should be in contact with the soil, while the sprout remains above the surface to continue growing. It is recommended to space the plants about 10 to 15 cm apart and leave 25 to 30 cm between rows to facilitate maintenance and air circulation.
Plant a sprouted onion by separating the bulbils
Some sprouted onions develop several shoots or bulbils around the base. In this case, it's possible to carefully separate each portion while keeping part of the main root. Each bulbil can then be replanted individually in the ground or in a pot with the same spacing as for a whole bulb, allowing you to obtain several plants from a single sprouted onion.
Sowing onions to complement the crop
In addition to replanting sprouted bulbs, onion seeds can be sown directly in the ground or in pots. Sowing is generally done at a depth of 1 to 2 cm, with 2 to 3 cm between seeds. This method allows you to fill the gaps left by the replanted bulbs and extend the harvest by obtaining young plants ready for transplanting or eating.
Spacing and Depth
Planting depth and spacing are essential for strong root development and bulb growth. Each bulb should be planted so that the sprout is slightly above the soil surface, with 10 to 15 cm between plants and 25 to 30 cm between rows. Adhering to these distances ensures not only even growth but also better air circulation and easier access for maintenance, watering, and harvesting.
Care after planting a sprouted onion
spray
THEspray This is essential to promote root development and shoot growth after planting. The soil should be kept moist, but never waterlogged, to prevent bulb rot. During dry periods, regular watering of about 1 to 2 liters per plant is sufficient, preferably in the morning or evening to limit evaporation and reduce the risk of foliar diseases.
Weeding and mulching
Regular weeding reduces competition for water and nutrients and limits the spread of disease. Organic mulch, such as straw or compost, helps keep the soil cool and moist while suppressing weed growth. It's advisable to leave space around the bulbs to allow air to circulate freely and prevent young shoots from being smothered.
Thinning and growth management
When several shoots develop from the same bulb, thinning is necessary to keep only the strongest plants. This involves removing the weakest shoots to leave enough space for the others to develop properly. Proper thinning promotes larger bulbs and even plant growth.
Fertilization during cultivation
Onions benefit from moderate nitrogen inputs to support leaf and root growth. A balanced organic or mineral fertilizer can be applied every 3 to 4 weeks, taking care not to over-fertilize the soil to avoid excessive foliage growth at the expense of the bulb. Adding compost or well-rotted organic matter can also gradually provide the necessary nutrients throughout the growing season.
Prevention and treatment of diseases after planting a sprouted onion
Onion blight
Downy mildew, caused by fungi of the genus Downy mildewThis disease manifests as yellow or brown spots on the leaves and can lead to bulb rot. To prevent it, it is advisable to plant onions in well-drained soil and avoid overhead watering, which wets the foliage. If infection occurs, removing affected leaves and spacing the plants to improve air circulation helps limit the spread of the fungus.
White rot
White rot, caused by Sclerotium cepivorumThe disease primarily attacks the roots and base of the bulb, leading to rapid wilting. Effective prevention involves not replanting onions in soil that has already been infected and ensuring good soil aeration to avoid excessive moisture. Since no curative treatment is reliable, eradication relies on the removal of diseased bulbs and crop rotation.
Botrytis or collar rot
This disease, caused by fungi of the genus BotrytisThis condition manifests as a grey, felt-like growth on the base of the stem and leaves, which can lead to bulb rot. Prevention involves proper spacing of the plants and ensuring good air circulation. If infection occurs, it is recommended to remove and destroy the affected parts and limit excessive moisture around the bulbs.
Good practices for limiting diseases
To reduce the risk of disease, it is important to select healthy bulbs, avoid overly wet soils, and practice regular crop rotation. Weeding and mulching also help limit moisture around the base of the bulb and the foliage. Finally, regular monitoring allows for the early detection of the first signs of disease and intervention before the infection spreads.
Pest control after planting a sprouted onion
Onion fly
La onion fly (old delia) Is a insect A common pest that lays its eggs at the base of bulbs, causing the plants to wilt and rot. To limit infestations, it is advisable to cover the rows with insect netting and practice crop rotation over several years. In case of infestation, removing and destroying affected plants helps reduce the population and prevent the spread to healthy plants.
Onion thrips
thrips (Tabaci ThripsThese insects feed on leaf sap, causing yellowing and stunted growth. Prevention relies on sufficient spacing between plants and removing plant debris where insects can nest. The use of sticky traps or neem-based products can also help control these pests naturally.
Nematodes and other soil parasites
Nematodes and other soil pests attack the roots and crown of onions, causing deformities and stunted growth. Good soil preparation, including weeding and loosening, as well as crop rotation, limits their proliferation. In infested soils, it is advisable to alternate with non-susceptible crops to gradually reduce the pest population.
Natural methods to protect plants
Simple cultivation techniques allow onions to be protected without the use of chemicals. Mulching reduces soil moisture and limits insect egg-laying. Sowing or planting companion plants Repellent plants, such as carrots or lettuce, can also help to keep some pests away while promoting biodiversity in the vegetable garden.
Harvesting after planting a sprouted onion
Recognizing when to harvest the bulbs
Onions grown from sprouted onions are harvested when the foliage turns yellow and begins to fall over naturally. This stage indicates that the bulb has reached its maximum size and its reserves are concentrated within it. It is important to regularly check the plants to prevent the bulbs from rotting or cracking from being left in the ground for too long.
Harvesting is carried out progressively according to the stage of maturity.
For dense plantings, a phased harvest is possible by first removing the most mature bulbs. This allows the remaining plants to continue developing fully. Young onions grown from sprouted onions can be harvested earlier, when they reach a size suitable for eating or transplanting, generally 4 to 6 weeks after planting.
Harvesting young onions
Young onion shoots can be cut as soon as they reach about 10 to 15 cm in height. Harvesting is done at the base of the leaves, leaving the bulb in the ground to continue production if needed. This method allows for several successive harvests from the same sprouted onion and makes the most of the initial bulb's vigor.
Storage after harvesting onions
Drying the onions after harvest
After harvesting, onions must be dried to prolong their shelf life. They are spread out in a dry, well-ventilated place, away from direct sunlight, for about 2 to 3 weeks. The foliage and roots gradually dry, which reduces the moisture around the bulb and prevents the development of mold.
Ideal storage conditions
Dry onions keep best in a cool, dry, and dark place, with a temperature between 15 and 20°C and good air circulation. It is recommended to hang them in braids, place them in nets, or arrange them on racks to avoid prolonged contact with damp soil. Excessive humidity should be avoided, as it promotes rot and premature sprouting of the bulbs.
Shelf life of bulbs
Under optimal storage conditions, onions can be kept for several weeks to several months. Thin-skinned varieties, such as white onions, tend to keep for a shorter time than thick-skinned yellow onions. It is advisable to regularly check the bulbs and remove any that show signs of sprouting or rotting to preserve the quality of the others.
Soil maintenance after harvest
Cleaning of crop residues
After harvesting, it is important to remove all plant and leaf debris left on the ground. This debris can harbor diseases or pests that could infect subsequent crops. Thorough cleaning helps minimize the risk of contamination and prepares the soil for new plantings.
Crop rotation after onions
Onions deplete certain soil resources and are susceptible to the same diseases if grown repeatedly. Therefore, it is recommended to practice crop rotation over several years, alternating with unrelated vegetables such as carrots, lettuce, or beans. This practice helps restore soil fertility and limit the proliferation of pests specific to onions.
Prepare the plot for the following crops
Once crop residues have been removed and the crop rotation planned, it is advisable to work the soil deeply to loosen it and incorporate compost or an organic amendment. This preparation promotes soil structure, improves water retention, and provides the necessary nutrients for subsequent crops. Well-prepared soil ensures a good start for later sowings or plantings and contributes to more abundant harvests.
Conclusion
Planting sprouted onions is a simple and economical way to obtain new plants or young onions from bulbs that have already sprouted. By following the steps of choosing the right variety, preparing the soil, planting, and maintaining the onions, it is possible to maximize bulb development while minimizing the risk of disease and pests. Harvesting, whether gradual or complete, must be done at the right time to guarantee onion quality, and proper storage extends their shelf life. Finally, careful soil maintenance after harvest effectively prepares the plot for future crops.
FAQ
How to plant a sprouted onion at home?
To plant a sprouted onion, choose a firm bulb with healthy green shoots. Dig a shallow hole, place the bulb with its base in contact with the soil and the sprout above the surface. Water regularly and ensure the soil is well-drained to encourage root development.
When to plant a sprouted onion in the garden?
Planting takes place when the risk of frost has passed and the soil reaches at least 10°C. In temperate regions, this generally corresponds to the beginning of spring. Follow the phases of the moon it also helps to maximize growth.
What distance should be respected when planting a sprouted onion?
Plants should be spaced approximately 10 to 15 cm apart in rows, with 25 to 30 cm between rows. This spacing allows the roots to develop properly and the foliage to receive sufficient light. It also facilitates maintenance and air circulation, thus limiting disease.
How to care for a sprouted onion after planting?
Maintenance includes regular watering to keep the soil moist but not soggy. Frequent weeding and light mulching help limit competition and water evaporation. Moderate applications of fertilizer or compost support bulb growth without excessive foliage.
How to harvest and store an onion?
Harvesting takes place when the foliage yellows and begins to fall naturally. The bulbs should be dried in a well-ventilated area, away from direct sunlight. Once dry, they can be stored for several weeks in a cool, dry, and dark place with good air circulation.
