Onion Sets - Key Growing Information
SCIENTIFIC NAME: Allium cepa
CULTURE: Onion sets should be planted as soon as possible — ideally within one week of receiving them. If you cannot plant immediately, store in a cool, dry, and dark place with good ventilation. Onions require a fertile, well-drained soil with a pH of 6.2-6.8. Sandy loam soils are ideal, so raised beds or raised rows are recommended for heavier soils to promote soil drainage. Full sun is required for optimal growth. Onions require frequent irrigation and the equivalent of 1" of water per week.
PLANTING: Plant sets in early spring, as soon as the soil can be worked. Plant approximately 1" deep with the base of the bulb (root-end) facing down, 4" apart in rows 12-18" apart.
DISEASES, INSECTS & WEEDS: Adequate air circulation aids in reducing the risk of foliar disease. Thrips are the most common Allium crop pest. Reduce overwintering habitat by keeping fields free of weeds and debris. Controlling weeds is also critical to the success of your onion crop.
HARVEST: Necks will become soft and tops will begin to fall over when mature. When approximately 50% of the tops have fallen over, pull the onions out of the ground and let dry in the sun for 2-7 days. When foliage and necks are completely dry, clip roots and cut back tops to 1". 'Forum' is not a long-storage onion, but if properly cured will store for approximately 3 months.