How to Grow
Onions and Shallots

Mastering the art of how to grow onions is a gratifying journey that yields delicious rewards. Whether you're a seasoned gardener or a budding enthusiast, cultivating onions and shallots can be both fulfilling and flavoursome. In this comprehensive guide, we'll unveil the secrets of nurturing these kitchen essentials, providing insights into different approaches: sowing from seeds, nurturing young plants, or utilising sets – those petite bulbs with immense potential.

Seeds, sets or plants? Choosing the Ideal Path for Growing Onions and Shallots

When it comes to cultivating onions and shallots, the method you choose – seeds, sets (small bulbs), or plants – plays a significant role, each offering its own set of benefits and considerations:

Onion & Shallot Sets:


  • Sets provide a straightforward experience, making them an excellent choice for beginners.
  • They are less susceptible to pests and diseases, ensuring a smoother cultivation journey.
  • Sets mature earlier, allowing you to enjoy your harvest sooner.


  • While reliable, sets offer a narrower range of varieties compared to other methods.
  • There is a slightly higher chance of bolting – the production of flowers instead of bulbs – with sets.

Onion & Shallot Seeds:


  • Seeds grant access to a wide array of onion and shallot varieties, catering to diverse culinary preferences.
  • Growing from seeds reduces the likelihood of bolting, ensuring a higher yield of bulbs.
  • With seeds, you have the freedom to sow according to your local climate and schedule.


  • The process demands more effort in terms of nurturing and care.
  • Seeds take longer to grow into mature bulbs, requiring patience and consistent attention.
  • Seedlings are more susceptible to pests and diseases, necessitating vigilant management.

Onion & Shallot Plants:


  • Plants offer a hassle-free approach, perfect for those seeking convenience.
  • Young plants have a head start in growth, making them less susceptible to pests and diseases.
  • Due to their advanced growth stage, plants lead to a shorter cultivation timeline.


  • Similar to sets, the choices in onion and shallot varieties might be somewhat limited.
  • Opting for plants can be slightly more expensive than other methods.

In your quest to grow onions and shallots, the method you select ultimately depends on your expertise, preferences, and goals. While sets offer reliability and early rewards, seeds provide diversity and flexibility, and plants bring forth simplicity and reduced vulnerability. By weighing the advantages and disadvantages of each approach, you can make an informed decision that aligns with your gardening aspirations.

Step-by-Step Guide: How to Grow Onions

Ideal Growing Conditions for Onions and Shallots

Creating the perfect environment for onions and shallots is pivotal for a successful harvest. Follow these guidelines to ensure optimal growth:

1. Choose a planting location that receives abundant sunlight throughout the day. Onions and shallots thrive in open, sunny sites, basking in at least 6-8 hours of direct sunlight. This sunlight exposure aids in robust growth and bulb development.

2. Prepare a bed of fertile soil that boasts excellent drainage. Loamy soil with a slightly acidic to neutral pH is ideal, ranging from 6.0 to 7.0. This soil composition provides the necessary nutrients for healthy growth while allowing excess water to escape, preventing root rot.

3. Infuse your soil with organic matter, such as well-rotted compost or aged manure. This enriches the soil's structure, enhances nutrient retention, and promotes moisture balance. The presence of organic matter contributes to the overall health of your onion and shallot plants.

4. Ensure that the chosen planting area hasn't been home to onions, shallots, or garlic for the past three years. This practice helps prevent the buildup of soil-borne diseases and pests specific to these crops. By practicing crop rotation, you safeguard the health of your plants and foster a thriving garden ecosystem.

By adhering to these guidelines and providing a nurturing environment, you'll set the stage for a bountiful onion and shallot harvest. Remember, the right combination of sunlight, soil, and care lays the foundation for culinary delights that are both flavorful and fulfilling.

Soil Preparation for Thriving Onions and Shallots

Creating a nourishing foundation for your onion and shallot crops begins with meticulous soil preparation. Follow these steps to ensure your plants flourish:

1. Several months before planting, embark on soil improvement by incorporating well-rotted compost into the designated area. This practice bolsters soil fertility, augments its structure, and facilitates optimal moisture retention. As compost gradually integrates into the soil, it provides a nutrient-rich base for your plants to thrive.

2. Harness the power of specialised onion fertiliser to equip your plants with essential nutrients for robust growth. This tailor-made fertilizer addresses the unique nutritional needs of onions and shallots, promoting vigorous foliage development and bulb formation.

3. For soils veering towards acidity, consider applying lime during the autumn and winter seasons. Lime helps neutralise soil acidity, creating a more favourable environment for onion and shallot growth. By optimizing soil pH, you enhance nutrient availability, allowing your crops to flourish.

4. Prior to planting, eliminate any existing weeds from the planting area. Weeds compete with your onion and shallot plants for essential resources, hampering their growth. Clearing the area of weeds sets the stage for unhindered development.

By conscientiously adhering to these soil preparation steps, you're sowing the seeds for a thriving onion and shallot garden. The fusion of compost, specialized fertilizer, pH adjustment, and weed management harmonizes to create a nurturing canvas where your crops can flourish to their fullest potential.

Perfect Timing for Growing Onions and Shallots

Mastering the art of timing is crucial when it comes to cultivating onions and shallots. Follow these seasonal guidelines to ensure your crops thrive:

1. Planting Sets: For those opting to grow from sets, there are two optimal time frames:

  • Plant sets in the fall for a head start in the spring. This allows the roots to establish before winter.
  • Alternatively, sets can be planted in the early spring. This is an excellent option for regions with harsh winters.

2. Planting Onion Plants: Transplant onion plants into your garden bed during the mild months of April. By this time, the threat of frost is minimal, giving your young plants the ideal conditions to flourish.

3. Sowing Onion and Shallot Seeds: For those who prefer to start from seeds, timing is crucial:

  • Sow onion and shallot seeds during these months to provide them with sufficient time to establish before winter.
  • Alternatively, begin sowing seeds indoors during these months, so they're ready for outdoor transplantation when the weather warms.

4. Spring Onions: Spring onions have their own set of planting periods:

  • Plant spring onions during the spring for a fresh harvest during the warmer months.
  • For winter-hardy spring onions, sow during this window to enjoy a bounty even as the temperature drops.

By adhering to these seasonal planting timelines, you're maximizing your chances of a successful onion and shallot harvest. The strategic alignment of planting with nature's rhythms ensures that your efforts yield flavorful and abundant rewards.

grow onions
onions and shallots

Planting Onions and Shallots

Planting Sets:

  1. Place onion and shallot sets in the soil with their pointed ends facing upwards. This ensures proper growth orientation.
  2. Leave 5 to 10cm (2 to 4 inches) of space between individual onions and 15 to 20cm (6 to 8 inches) between shallots.
  3. Create rows of onions with 25cm to 30cm (10 inches to 1 foot) of spacing between them. For shallots, allow 30 to 45cm (1 foot to 18 inches) between rows.

Planting Onion Plants:

  1. Utilise a dibber to create holes in the soil that are the same depth as the plants' original root depth in their cell tray.
  2. Place the plants into the holes, ensuring they sit at the same depth they were in their cell tray.
  3. Gently water the area to facilitate proper settling of the plants into the soil.

Sowing Onion and Shallot Seeds:

  1. Begin in late winter or early spring by sowing seeds in a seed tray indoors.
  2. Once the seedlings reach about 1cm in height and show their "crookneck" stage, gently transplant them, giving each seedling about 5cm of space.
  3. Gradually acclimatize young plants to outdoor conditions by allowing them to "harden off" – developing two or three leaves – before transferring them to their final outdoor positions in mid to late spring.
  4. Alternatively, when the weather is warmer, sow seeds directly into well-prepared soil with a fine texture. Create shallow rows about 2cm deep and space them around 30cm apart.
  5. As the seedlings grow, thin them out to maintain proper spacing for healthy growth.

Watering Onions and Shallots

Water deeply and thoroughly when necessary, ensuring the soil is moist to a significant depth. The goal is to keep the root zone consistently moist without letting the soil become waterlogged.

Shielding and Safeguarding Onions and Shallots

Guarding your onions and shallots from potential threats ensures their uninterrupted growth and eventual success. Employ these protective measures to nurture your crops effectively:

1. Utilise Horticultural Fleece:

  • Cover emerging onion and shallot plants with horticultural fleece. This acts as a barrier, safeguarding them against birds that might try to uproot or damage the young plants.
  • Be vigilant about removing the fleece once the plants are firmly established. Leaving it on for too long can limit air circulation and promote disease development.

2. Precise Weeding:

  • Tackle weeds by hand rather than resorting to tools like hoes. This cautious approach prevents accidental damage to the bulbs during weeding.
  • Carefully remove weeds around the onion and shallot plants, ensuring minimal disturbance to the delicate root syst

How and when to harvest onions and shallots

1. Harvesting Shallots and Onions:

  • Once the foliage of your shallots and onions has turned yellow and started to wither, it's time to harvest. This typically occurs in late summer to early autumn.
  • Gently lift the plants using a fork, loosening the soil around the bulbs. Avoid damaging the bulbs during this process.
  • After lifting, remove excess soil from the bulbs. Allow the shallots and onions to dry for about two weeks in a well-ventilated area that's cool, dry, and has some light. This process helps the outer skins to dry and cure, promoting better storage.
  • Once dried, trim the roots and tops, leaving about 2-3 cm of stem. Store the shallots and onions in a cool, dry place with good air circulation.

2. Seasonal Harvest for Different Varieties:

  • Harvest these crops in June or July when the leaves have turned yellow and dried.
  • For spring-planted varieties, plan to harvest from August to September. The same yellowing and drying of foliage serve as a reliable indicator.
  • Harvest spring onions from May to September. These versatile onions can be enjoyed throughout the warmer months.
  • If you've planted winter-hardy spring onions, anticipate harvesting from February to May, giving you fresh produce even in colder months.

Identifying and Addressing Common Onion and Shallot Issues

Vigilance in monitoring your onion and shallot plants is crucial for preventing and managing potential problems. Here's a breakdown of common issues and their respective remedies:

1. Onion Fly:

  • Yellowing leaves on mature plants.
  • Promptly lift and burn affected plants to prevent the spread of the infestation.

2. Bulb Rot:

  • Yellowing of plants, with dying leaf tips. Affected plants might have missing roots.
  • Unfortunately, plants with bulb rot are unlikely to recover. Preventive measures include planting in well-draining soil and avoiding over-watering.

3. Smut (Fungal Disease):

  • Black blisters on leaves, leading to stunted and distorted plant growth.
  • Remove and destroy affected plants to prevent further spread. Proper spacing, adequate air circulation, and avoiding over-watering can help prevent smut.

4. Shank (Disease):

  • Shrinking, yellowing leaves and soft bulbs.
  • Unfortunately, there's no cure for shanking. Practice crop rotation and provide well-draining soil to reduce its occurrence.

5. Onion White Rot:

  • Withering foliage during dry weather, with a white fluffy mold developing at the base.
  • Affected plants can't be saved. Prevent white rot by planting disease-resistant varieties and avoiding planting where alliums have been grown in recent years.

Careful observation, timely action, and implementing preventive measures are your best strategies for maintaining the health and vitality of your onion and shallot crops. Regularly inspect your plants and stay attuned to any changes to ensure a successful and rewarding harvest.

Onions, Shallots & Garlic

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