How Often to Water Spring Onions
Of everything in the veg patch, spring onions are among the least demanding to water. They grow fast, they're ready in around eight weeks, and once they're past the seedling stage they're fairly tolerant of the odd dry day. They really rely on you at three points: germination, the first few weeks as tiny seedlings, and any long spell without rain, particularly if they're in a pot.
Get those moments right and you'll have a steady supply of tender, mild spring onions from spring to autumn. Leave them thirsty for too long and you'll get skinny, stringy stems with a harsh bite, and some may flower.
How often should you water spring onions?
Water spring onions regularly until the seedlings are established, keeping the soil lightly damp. After that, plants in the ground generally only need watering during prolonged dry spells, when a good drink once or twice a week is usually enough. In pots and window boxes, though, have a look most days when it's warm, as shallow compost dries out fast.
Watering before and after sowing
If the soil is dry when you come to sow, water the row the day before. Sowing into ground that's already moist gives the seeds the best chance of germinating evenly, and you avoid washing the small seeds out of the drill by watering heavily straight afterwards.
Once sown, keep the surface lightly moist until the seedlings are up and growing strongly. This is the stage when they're most likely to suffer from drying out.
Watering spring onions in garden beds
In the open ground, your watering can mostly comes out for young seedlings and for dry weeks with no rain.
Once established, a thorough watering in dry weather is better than a daily sprinkle. The soil should feel slightly damp below the surface. Water at the base rather than over the leaves if you can.
Keep the rows weed-free. Spring onions have slim, upright leaves and shallow roots, so weeds easily crowd them out and take the moisture they need. A hoe works well between rows, but tease out weeds growing among the plants by hand.
Watering spring onions in containers
Spring onions happily grow in shallow containers, which makes them ideal for a balcony, but that small volume of compost dries out fast on hot or breezy days. Feel the compost regularly and top it up with water as soon as it's dry a centimetre or two down. A liquid seaweed feed every few weeks keeps container spring onions growing well.
For container advice, see growing spring onions in containers
Spring onions vs bulb onions
If you grow bulb onions too, you may know that they should stop being watered in mid-summer so the bulbs ripen and store well. Spring onions are different. They're pulled green and eaten fresh, so there's no ripening or storing to worry about. Keep watering whenever the weather is dry, right up until you harvest them.
When spring onions need more water
Keep a closer eye on moisture straight after sowing, in the seedlings' first few weeks, and whenever the weather turns warm and dry.
Signs of watering problems
Tough, thin or very strong-tasting spring onions: the soil has been too dry.
Plants flowering early: stress from drought or heat.
Yellowing, rotting plants: soil that stays waterlogged.
Avoiding overwatering
Spring onions dislike soggy ground and can rot in waterlogged soil. Grow them in well-drained soil, avoid watering when the ground is already wet, and make sure pots have drainage holes.
You can read more in how often to water a vegetable garden
Healthy spring onion growth
For a steady supply of tender spring onions, keep seedlings moist, water established plants in dry spells, weed regularly, and sow a short row every few weeks from spring to late summer.
For growing advice, see how to grow spring onions in the UK
For timing, see when to plant spring onions and when to harvest spring onions
Common questions
How often should I water spring onions?
Water regularly until the seedlings are established. After that, plants in the ground usually only need watering in prolonged dry spells. In pots, check most days while the weather is warm.
Do spring onions need a lot of water?
They need steady moisture while they're young, but once established, spring onions are fairly tolerant of short dry spells. Long periods of drought make them tough and can cause them to flower.
Should I keep watering spring onions until harvest?
Yes. Unlike bulb onions, which are left dry in late summer to ripen, spring onions are eaten fresh, so keep watering them in dry weather right up until you harvest.
Should I water spring onion seeds before or after sowing?
Soak the drill a day ahead if the ground is dry. That way the seeds go into moist soil without being washed away.
Growing advice checked against RHS guidance.