How to grow Onions

CULTURE: If your field or garden has full sun and is fertile and well-drained (no standing water after heavy rain) you can grow large, sound onions from seed. The best crops are grown in humus-rich sands, light loams, or high organic matter peat and “muck” soils. Onions from seeds or plants are generally better than set-grown onions.

DIRECT SEEDING: In April or early May or as soon as the soil can be prepared in early spring, sow in a 2″ wide band, about 2 seeds/in., 1/4- 1/2″ deep, rows 12-18″ apart. Thin to 1 1/2-2″ apart for highest yields on fertile soil. Thin to 3-4″ apart for larger onions and 4″ apart for the “sweet mild” type.

TRANSPLANTING: For varieties of the “sweet mild” class, and for the storage type in extremely short season areas, sow seeds indoors in flats in late February to mid-March. Broadcast 1/2″ apart and cover 1/4″. Tops may be clipped to 5″ tall. Transplant to the garden 4″ apart, or sow 5 seeds in each cell of 1-1 1/2″ diameter plug trays, thinning to 3 per cell. Transplant each cell 6″ apart.

CULTIVATION: Keep onions well weeded with shallow cultivation.

WATER: Onions are shallow rooted and grow best with at least an inch per week of rain or irrigation.

DISEASES: Set-grown onions are more prone to disease than seed-grown onions. If you grow from both sets and seeds, plant in different locations to help avoid any disease spreading to the seed-grown crop.

HARVEST: When onions have begun to develop skins and tops are falling over, pull and sun-cure at least a week before removing tops.

STORAGE: When dry, clip off tops and store in onion bags or shallow boxes at near freezing and 65-70% humidity.

DAY LENGTH: Onion varieties differ in the length of day required to make a bulb. Those requiring fewer daylight hours are grown in the South where the daylight period during summer is shorter than in the North. Most of our varieties are of the “medium” or “long-day” type, and if they are grown in the South, the days there are too short to initiate good bulb development. Refer to “Adaptation” in each variety description for details.

DAYS TO MATURITY: From direct seeding; subtract 10-15 days if transplants are used.

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