Onions grow best in full sun and deep, fertile, well-drained soil with plenty of organic water. Work in a generous amount of organic compost or well-aged animal manure prior to planting. Onions are shallow rooted and need constant moisture near the surface.
Onions form bulds in response to day length. If you choose a type inappropriate for your area, it may make small, premature bulbs or no bulb at all. Long-day varities, sweet spannish included, need 14-16 hours of daylight and are grown i nothern climates. Short day varieties. Bermuda included, need 10-12 hours of daylight. These start making bulbs early in the year. Select an onion type that is suited to your zone for best results.
How To Plant
You can grow onions from seed, seedlings or sets. Sets. Sets mature quickly and are easy to grow, but varieties are limited. Seed should be sown in the fall to set bulbs i spring or summer.
Allow 2-4 inches between plants in traditional rows spaced 1-2 feet apart. Feed the plants with a high quality organic vegetable fertilizer early in the season and apply liquid fish and seaweed later in the season to improve crop yields, taste and appearance.
Harvesting
Allow tops to fall over naturally, then pull bulbs and let them air-cure for two weeks. Watering prior to harvest makes pulling easier. After curing, store the bulbs in a cool, dry place such as the cellar. Onions reach maturity 80-100 days after direct seeding; 30-40 days from sets.
Insects and Diseases
To help prevent insect and disease problems avoid planting onions in the same area for three years. Damage to the lower part of the stem is often caused by the union maggot. Thrips are suspected if onions become bleached and wither. Wireworms can also cause serious damage as they feed on all underground parts.
Common disease include botrytis rot and downy mildew, both of which are characterized by soft tissue and mold.
Seed Saving Instructions
Biennial. Onions cross-pollinate and should be isolated by 1 mile from other onions going to seed. Select only the best bulbs and store 3-6 months at 32-45 F. Plant out bulbs in early spring and allow them to form seed heads. When the heads start to dry. Cut off the tops, dry further and thresh.
