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Watering schedule

How often to water White Onion (Allium cepa 'Sturon') — the schedule

Also called Sturon onion, white onion, globe onion.

More about white onion

About White Onion

Allium cepa 'Sturon' · also called Sturon onion, white onion · edible

The bulb onion is a biennial allium grown as an annual for its swollen storage bulb. 'Sturon' is a popular, reliable globe variety usually grown from heat-treated sets, giving uniform, well-keeping, mild bulbs that resist bolting. Bulbs swell through summer as daylength lengthens, then ripen and are lifted and dried in late summer for long storage.

Ideal humidity: Ambient outdoor

Watch for — Onion white rot: Soil fungus that rots the roots and base with fluffy white mould; plants yellow and topple. There is no cure, so rotate alliums on a long cycle and use clean ground.

The watering schedule, season by season

White Onion crops best on deep, regular soaks rather than light daily sprinkles — steady moisture at the roots is what fills and sizes the harvest. The base rhythm for white onion is when the top 2-3 cm of soil is dry, roughly weekly; reduce as bulbs ripen, but the real interval moves with the season, the light and the pot — so treat the figures below as a starting point and always confirm with the plant itself.

Keep evenly moist during bulb swelling, but stop watering once the tops start to flop and the bulb matures, as wet soil at ripening promotes neck rot and poor storage.

Want this turned into a live reminder that adjusts to your home and the weather? The Growli watering calculator takes your pot size, light and season and returns a starting interval for white onion in seconds.

How to tell white onion needs water

A calendar is the worst way to water white onion. Check the plant and the soil instead — for this species, look for these signals in order:

The most reliable single check is the first one on that list. When two signals agree, water; when they disagree, wait a day and look again — under-watering white onion for a day is almost always safer than over-watering it.

Overwatering vs underwatering white onion

The two failure modes can look alike at a glance, so check the soil weight and wetness before you decide. For white onion specifically:

Signs you are overwatering

Signs you are underwatering

Shallow, frequent watering grows shallow roots and leaves white onion prone to drought stress — cracked or woody roots, bitterness and premature bolting. Water deep and at the base, not little-and-often over the leaves.

Water quality notes

Tap water is fine for white onion; consistency and depth matter far more than water type. Water early in the day at soil level to limit fungal disease.

Seasonal and environmental adjusters

Every figure above shifts with the conditions in your home. For white onion, the levers that matter most are:

Pot choice is part of this too — work out the right size with the pot size calculator, since a pot that is too big stays wet long enough to rot the roots of white onion.

White Onion watering — frequently asked questions

How often should I water white onion?

Water white onion when the top 2-3 cm of soil is dry, roughly weekly; reduce as bulbs ripen. Main season: aim for the equivalent of 2-3 cm of water per week as one or two deep soaks at the base, more in heat or during fruiting/sizing. Off-season: most do not overwinter outdoors — store, mulch, or grow undercover; container plants need only occasional water if dormant.

How do I know when white onion needs water?

Push a finger 3-4 cm into the soil — if it comes back dust-dry, water now. Leaves wilt in the midday heat and do not fully recover by evening. The soil surface is cracked or pulling away from the bed/pot edge. The single most reliable test for white onion is the first signal on that list — checking the soil or the plant directly always beats watering by the calendar.

What does an overwatered white onion look like?

Yellowing lower leaves and waterlogged, airless soil. Root rot and wilting despite wet soil; fungal leaf spots from constantly wet foliage. Split or cracked fruit/roots from a sudden glut after drought. Shallow, frequent watering grows shallow roots and leaves white onion prone to drought stress — cracked or woody roots, bitterness and premature bolting. Water deep and at the base, not little-and-often over the leaves.

What are the signs of an underwatered white onion?

Persistent wilting, small or bitter produce, premature bolting. Blossom-end rot on tomatoes/peppers/squash from erratic moisture. Tough, woody or cracked roots in root crops.

Can I use tap water on white onion?

Tap water is fine for white onion; consistency and depth matter far more than water type. Water early in the day at soil level to limit fungal disease.

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