How to Sow and Grow Onions

Onions are a key ingredient in kitchens everywhere, adding flavour to many dishes. Growing onions at home is easy and rewarding—they need little care and can produce a good harvest. This guide will help you, whether you’re new to gardening or experienced, to plant, grow, and harvest onions successfully.

Onion Cipolla Ramata De Milano

When to Start Planting

The best time to plant onions depends on your location and the type of onion you’ve chosen:

• Direct Sowing Outdoors: In most climates, onions can be sown directly outdoors in early spring, around 4-6 weeks before the last expected frost date. In mild climates, they can also be planted in the fall for an early spring harvest.
• Indoor Starting: For a head start, start onion seeds indoors about 8-12 weeks before the last frost date. Transplant seedlings outdoors when they reach around 24 cm in height.

Preparing the Soil

Onions prefer loose, well-draining soil rich in organic matter. Here are some tips for soil preparation:

• Soil pH: Onions thrive in slightly acidic to neutral soil with a pH between 6.0 and 7.0. Test your soil and amend it if necessary.
• Composting: Incorporate compost or well-rotted manure into the soil to increase nutrients and improve texture.
• Tilling: Loosen the soil to a depth of 48 cm and remove any rocks or debris to make room for the onion bulbs.

Onion Italian Flat

Sowing Onion Seeds or Sets

You can grow onions from seeds, sets (small onion bulbs), or transplants:

• Seeds: Sow seeds 1 cm deep and space them about 4 cm apart in rows spaced 48 cm apart. Thin the seedlings to 16 cm apart when they are a few cm tall.
• Sets: Onion sets are small pre-grown bulbs that give a head start on growth. Plant them 4-8 cm deep, with the pointed end facing up, spaced 16 cm apart in rows.
• Transplants: If you started your onions indoors, transplant them into the garden when they are about 24 cm tall, following the same spacing guidelines as for sets.

Watering

Onions have shallow roots and need consistent moisture but avoid overwatering, as this can cause rot:

• Watering: Water your onions deeply once or twice a week, depending on rainfall and soil type. Aim for around 4 cm of water per week.
• Mulching: Apply a thin layer of mulch around your onions to retain moisture and suppress weeds.

Perennial Nodding Onion

Weed and Pest Control

Weeds compete with onions for nutrients and water, so keep the area around your onions weed-free. Hand-pulling is ideal as onions have shallow roots that can be disturbed by tools. For pest control, keep an eye out for common pests like onion maggots and thrips. To deter pests, consider:

• Row Covers: Protect your onions from pests by using lightweight row covers, especially when plants are young.
• Rotation: Avoid planting onions in the same spot year after year, as crop rotation helps prevent soil-borne diseases and pests from establishing.

Harvesting Onions

Knowing when to harvest onions is key to getting the best flavour and longest shelf life:

• Signs of Maturity: Onions are ready to harvest when the tops turn yellow and begin to fall over. Gently bend over any remaining upright tops to speed up this process.
• Harvesting: Once the tops are fully dry, carefully lift the onions from the soil using a garden fork. Let them cure by laying them out in a warm, dry area with good airflow for two to three weeks.
• Storage: After curing, trim the tops and roots, and store your onions in a cool, dry place. Storage onions can last for several months, while sweet onions have a shorter storage life.

Onion Long Red of Florence

Growing onions at home is not only easy but also satisfying, as they provide a fresh and flavourful addition to your kitchen. With the right variety, soil preparation, and care, you’ll enjoy a productive onion harvest that can last well into the winter. Whether you use them fresh, store them, or even pickle them, there’s nothing quite like the taste of homegrown onions. Happy growing!

Video – How to Sow and Grow Onions