White onion: Sowing, planting and harvest calendar
How do you sow white onions outdoors?
Sow your white onions in spring as soon as the soil warms up and becomes workable. Late-summer sowing can suit some overwintering varieties, depending on your climate: check the seed packet rather than using one date for all white onions. Choose sun and a fine, weed-free, well-drained seedbed, without fresh manure.
Sow thinly about 1–1.5 cm deep, in rows 20–30 cm apart. Cover lightly, firm gently and keep the surface moist until germination, without soaking it. Thin progressively: for developed bulbs, leave about 10 cm between plants. Closer spacing can suit a crop of small fresh onions if the variety is suitable.
Weed by hand near young plants and water in dry weather. For fresh use, harvest at the size you want while the leaves are still green; for mature bulbs, wait until they ripen. The time needed depends on variety, season and harvest stage, so three months is not a general rule.
How do you plant white onions?
To plant your white onions, choose a sunny, weed-free plot with good drainage. Prepare loose soil, without fresh manure or excess nitrogen. Timing depends on variety and climate: plant in spring, or in autumn only with planting material suited to local overwintering. Avoid frozen or waterlogged soil.
If you use sets, place them pointed end up and press them in gently, with the tip just visible at soil level. For seed-raised transplants, spread the roots in a small hole and plant shallowly, without burying the base of the leaves. Leave about 10 cm between plants for developed bulbs and 20–30 cm between rows; adjust spacing to the variety and the harvest size you want.
Water after transplanting to settle soil around the roots, then according to the weather, without standing water. Weed gently near the shallow roots. For a fresh crop, you do not need to wait until the leaves turn yellow; only mature, thoroughly dried bulbs of a suitable variety should be intended for storage.
How to care for this plant
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Weed
Remove weeds around young bulbs, especially if they shade them. Close to the plants, weed by hand to protect the roots and avoid damaging the bulbs.
How do you harvest white onions?
Harvest your white onions according to how you want to use them. For fresh use, lift them when the bulb reaches the size you want, with the leaves still green: there is no need to wait for them to yellow. The season depends on variety and sowing or planting date. Gently loosen the roots with a fork if the soil is firm, rather than pulling hard on the leaves.
Use young onions with their leaves promptly. Keep them in the refrigerator for a short time, without treating them as dried onions for long storage. If you grow a variety suitable for storage, wait for the bulbs to mature and the leaves to yellow and fall over naturally; do not bend the leaves to force ripening.
Dry these mature bulbs in a dry, well-ventilated place sheltered from rain until the necks and outer skins are dry. Store only healthy bulbs in nets or on slatted trays, somewhere cool, dry and frost-free with good airflow. Storage life depends on variety and drying. Use damaged or bolted bulbs first, discard rotting ones and check your stored crop regularly.
White onion
- Type : Vegetables
- Subtype : Bulb vegetables
- Botanical Family : Liliaceae
Characteristics
- Lifecycle : Annual
- Exposure : Full Sun
- Frost Hardiness : Frost Resistant
- Cultivation Difficulty : Easy
- Mature height : 30 cm
Sowing & Planting
- Greenhouse Growing : Not Required
- Sowing Depth : 2 cm
- Plant Spacing : 10 cm
- Row Spacing : 20 cm
Maintenance
- Maintenance : Low
- Water Requirements : Moderate
Other characteristics
- Soil Type : Humus-rich
- Soil pH Preference : Neutral
- Pest Sensitivity : Moderate
- Disease Sensitivity : Moderate
- Weed Sensitivity : Moderate
- Pollination : Insect-pollinated
- Propagation : Sowing