How to grow spring onions and best varieties

Spring onions are ideal for filling gaps in the veg patch. You can also grow them in containers and raised beds. They can be ready to harvest just eight weeks after sowing, and if you sow little and often you can be picking fresh crunchy onions for salads and stir-fries for many months. You can even grow some varieties to full-sized onions.

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How to grow spring onions: month by month

Best spring onion varieties

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Full testing results for spring onions

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When to sow

Despite their name, spring onions can be sown from February to July. Sow small amounts at intervals in fertile, well-drained soil and protect early sowings with cloches or fleece. From August onwards you can sow winter-hardy varieties, such as ‘White Lisbon’ and ‘Ramrod’.

You can sow spring onions in various ways. To sow where they are to grow, sow thinly 1-1.5cm deep into drills leaving enough space to hoe between rows. You can also sow in containers and raised beds. Alternatively, sow in modular trays indoors and plant out once the seedlings are large enough to handle.

Try a Best Buy compost for sowing seeds

Caring for your plants

Keep the ground moist and weed free; fast-growing weeds can out-compete spring-onion seedlings. Onions germinate slowly, so weed carefully between rows until plants are established. Hoe regularly to keep the weeds down and avoid competition. 

Watch out for signs of bolting (the production of flower heads) in hot weather. Snip off any flower heads that form and use the onions as soon as possible.

Mark your plants with Best Buy plastic-free labels

How and when to harvest

Pull spring onions when they’re pencil-thick and strip off outer leaves to leave a clean stem. Early sowings will be ready in around 10-12 weeks; early summer sowings can be ready to harvest in as little as eight weeks.

Try our Best Buy garden kneelers

Common growing problems

Rust

Leek rust is a fungal disease that affects members of the allium family – leeks, garlic, onions and spring onions. It appears as bright orange spots on the leaves. There is no chemical control available to gardeners. Rust is more prevalent in humid conditions; allowing space between plants improves airflow and reduces humidity.

White rot

White rot is caused by a fungus that destroys the roots, killing the plant. It then produces resting bodies that can last for many years in the soil.

Onions, shallots, garlic and leeks all suffer from this disease. Spring onions and overwintered onions seem particularly susceptible. 

Look out for yellow and stunted plants in May and June among your overwintered onions, and later in the other onion-family crops. When you pull up sickly plants, check for a white/grey mould around the base. In advanced cases, you will see black, pinhead-sized, regular spheres. These are the sclerotia, or resting bodies, that will carry the disease from one crop to the next.

When you see white rot, remove the plants and a few inches of surrounding soil. Burn or bin them. This will make sure that you don't add more sclerotia to the soil.

Avoid transplants grown in soil-based compost. Gather and use an attacked crop as soon as you can, as damaged bulbs will be unusable and won't store well. There are no chemicals available to gardeners to control this disease, and there are no resistant varieties.

How we test spring onions

We selected 19 widely available varieties of spring onions, including previous Best Buys and those with an RHS Award of Garden Merit. We included both red and white onions.

In early June, we sowed our spring-onion seeds direct into drills at our trial site in Cambridgeshire and used sprinkler irrigation to water the plot.

We weeded between the rows of spring onions every two weeks or so and watered the plot with a sprinkler after weeding.

In mid-August, we harvested and recorded the number and weight of usable onions for each variety. We also made a note of any that were too small or underdeveloped, and rated each variety for overall quality and ease of stripping the outer foliage to leave a clean shank and bulb.