Onion

SCIENTIFIC NAME:
Allium cepa

CULTURE:
Onions require full sun and fertile, well-drained soil with a pH of 6.0–7.0. Sandy loam soils are ideal; in heavier soils, use raised beds or raised rows to promote soil drainage.

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 in fertile soil. Thin to 3-4" apart for larger onions.

TRANSPLANTING:
In 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 1" per week of rain or irrigation, especially during the bulbing phase.

DISEASES:
Adequate air circulation and crop rotation aids in reducing the risk of foliar disease.

HARVEST:
When necks become soft and tops are falling over, pull and sun-cure at least 2–7 days, depending on weather. Move to a protected location to finish drying.

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

DAY LENGTH:
Onion bulbing is triggered by day length, and maximum day length during the growing season increases from south to north. Short-day onions are grown at lower latitudes in the South, while intermediate and long-day onions are grown at higher latitudes. Refer to "Adaptation" in each variety description for details.

DAYS TO MATURITY:
From direct seeding; subtract 10–15 days for days to maturity from transplant.