Exploring the World of Onions: A Comprehensive Guide
Onions are a versatile vegetable that can be grown as green onions or dry (storage) bulbs. For gardeners in Iowa and other northern areas, long-day and intermediate-day onion cultivars are the best choice.
Onions rely on photoperiod or day length to determine when bulb development begins. Long-day onions bulb when daylight exceeds about 14 hours, making these cultivars suited to northern climates. Some popular long-day onion varieties include Walla Walla (yellow, sweet onion), Redwing (red), Yellow Sweet Spanish, Candy (yellow, sweet), Copra (yellow storage onion), and Super Star (yellow storage onion).
Onions perform best in well-drained, slightly acidic (soil pH 6-7), fertile soils in full sun. When planting, space rows 12 to 15 inches apart with plants 4 to 6 inches apart when grown for mature storage onions and closer (1 inch apart) when grown for green onions.
Dry onions (also called storage onions) are harvested when the tops have fallen over and start to turn brown, typically 90-120 days after planting. After curing, they should be stored in a cool, moderately dry location. Storage temperatures should be 32-40°F and the relative humidity should be 65-70%. Proper drying and storage will help prevent black mold, a fungus caused by Aspergillus niger.
Green onions (also called scallions) are harvested young before the bulb starts to form. Specific bunching onions or scallions (Allium fistulosum) can also be grown, which do not form bulbs.
When it comes to managing diseases, cultural control methods are the best way to manage Fusarium basal rot and purple blotch. Practice good crop rotation, avoid overhead irrigation, and promptly remove and destroy any infected materials after harvest. For Fusarium basal rot, plant in well-drained soils and select varieties that are resistant to the disease.
Onion seed typically loses vigor quickly, and new seeds should be purchased each year. However, when properly stored, good keepers, such as 'Copra' and 'Stuttgarter,' can be successfully stored for several months. Poor keepers, such as 'Walla Walla' and 'Sweet Spanish,' can only be stored for a few weeks.
In conclusion, choosing from long-day varieties from trusted seed suppliers is essential for gardeners in Iowa. Seed suppliers often label onions as "long-day" for northern climates versus "short-day" for southern areas. It's also important to consider local trial results where available to optimize for yield, flavor, pest resistance, and storage life.
- In the realm of gardening, Iowa gardeners particularly benefit from long-day and intermediate-day onion cultivars, as these are suited for their northern climate.
- When it comes to选择种子供应商，对于花园 agriculture 爱BoolIo
