Growing Spring Onions in Scotland: The Complete Guide

Allium cepa (immature bulb onion)

Spring onions are one of the quickest, lowest-effort crops you can grow, ready in about two months and easy to keep going from spring right through to a hardy overwinteredKeeping a plant alive and intact through the cold months, whether left outdoors, moved under cover, or stored dormant. Full definition → crop the following year.

Spring onions ask for almost nothing beyond regular small sowings and a weed-free row. The one habit worth unlearning is waiting for a bigger harvest: this is a crop where pulling them young is the whole point, not a compromise. Sow a batch every few weeks through the growing season, and add a hardy autumn sowing if you want a crop that's ready before anything else you've started fresh that year.

Sowing

Sow outdoors from March, in small batches every few weeks, for a steady supply from spring through autumn rather than one glut. An early indoor sowing in modulesA tray divided into small individual cells, each sown with its own seed or seedling, so each plant grows undisturbed roots until it's ready to plant out. Full definition → in March is also an option if you want a head start on the first batch. Make a shallow drillA shallow, straight groove made in prepared soil for sowing seed into, at a set depth so germination and rows are even. Full definition → 1cm deep, and thin seedlings to about 2.5cm apart once they come up, using the thinnings in salads rather than wasting them.

Row spacing is one place the sources genuinely differ: RHS gives 20cm between rows, while a tighter 10cm is also workable if you want a denser row of thinner onions. Both are valid choices, and which one suits you comes down to how much bed space you have rather than one being objectively correct.

Sowing a hardy, overwintering crop

The name undersells this crop's range. A hardy variety such as White Lisbon can be sown in late summer or early autumn, protected through hard weather with a clocheA small, portable clear cover placed over an individual plant or short row to trap warmth and keep off wind, rain and pests. Full definition → or biodegradable fleeceA lightweight, breathable fabric laid or draped over plants to trap a little warmth and keep off frost, wind and some flying pests. Full definition →, and left to overwinter for harvest the following spring, well ahead of anything sown fresh that year. It's worth treating as a separate sowing on the calendar, not an afterthought to the main summer succession.

Rotation: spring onions share a family with onions and garlic

Track spring onions together with bulb onions, shallots and garlic in your rotationMoving each crop family to different ground each year, on a multi-year cycle, so pests and diseases that build up in soil don't get a repeat host. Full definition → plan, not as a separate, faster-growing exception. Leave a gap of 4-5 years before returning any of them to the same ground, to stop white rot building up in the soil.

Varieties

RHS also lists 'Guardsman' with AGMThe RHS's Award of Garden Merit: a UK-wide trials award for reliable performance, not a Scotland-specific recommendation. Full definition → (though the badge only appears on the general variety list, not its own individual plant page) and 'Photon' without AGM. The award is UK-wide, not a Scottish one. Some varieties can also be left to swell into a full bulb onion if you thin out every other seedling instead of pulling them all young.

Also worth considering

Best Spring Onion Varieties for Scotland → compares all named spring onion varieties head-to-head, with the practical detail that doesn't fit in a summary card.

Care

Water young plants until they're established, then only during prolonged dry spells; container-grown plants need watering more often than anything in the ground. Hoe between rows and hand-weed close to the plants, since a crowded row of spring onions has little room to compete with weeds on its own.

Harvesting

Pull at two months from sowing, young and small, around 15cm tall with the bulb no more than 1-2.5cm across, for the sweetest, mildest flavour. A 3m row sown thickly can give somewhere in the region of 250-300 onions across a season of repeat pulling.

Worth knowing: a perennial alternative

If replanting every few weeks isn't for you, bunching onions are a perennial alternative in the same family: you cut the leaves for use and leave the bulb in the ground to keep producing, rather than pulling the whole plant. Only one source mentions it, so treat it as worth trying rather than a fully proven option.

Common problems

• Slugs and snails are the main risk to young seedlings, particularly in a wet spring.
• Onion downy mildew damages foliage and bulbs and is encouraged by overcrowding. Thin seedlings properly rather than leaving a dense row.
• Onion fly maggots damage roots and bulbs and can kill seedlings outright. Fine mesh or fleece from sowing is the reliable defence, not a companion plant.

Common questions

Sources