Onions
For the Home Garden
Onions may be grown using sets, plants, or seeds. Planting will vary according to the availability, use and variety.
Sets. Sets are usually used to grow green onions (often called scallions), although they will produce onions for bulbs later in the season. Sets are small onion bulbs that were planted thickly, the previous season, to suppress large bulb development, stored through the winter and offered for sale in the early spring. Sets are usually poorly identified by variety, making it a gamble to know the flavor, use, or keeping quality of the mature bulbs. Place sets 1 to 1 ½ inches deep, close enough to touch each other in a single row or a wide bed planting. When plants are six inches or taller, they can be pulled for green onion to thin until 2 or 3 inches remain between onions grown for mature bulbs.
Plants. Plants are onion transplants grown in the fall or winter in southern areas and bundled in 50 to 100 plants per bunch offered for sale in spring. Onion plants are usually well identified as to variety and can make excellent mature bulbs. Choose healthy, green and fresh transplants and set them 1 to 1 ½ inches deep in rows 12 to 16 inches apart (or wider). Onions should be spaced 2 to 3 inches apart, depending on the size of the mature bulbs.
Seed. Onions can be grown from seed, but seeds are the slowest to develop – usually not ready for harvest until August in most areas of Kansas. Plant seeds early in Late March or early April, using one seed per inch in rows 12 to 16 inches apart. Onion seedling plants are slow to establish, so weed control will be critical in seeded onions.
Fertilization and Watering. Onions have a shallow, poorly developed root system, so regular fertilization and watering is essential. Organic material added to the soil in the fall helps to loosen soils and provides necessary fertility. Regular, uniform watering is essential for high yields and quality. Onions should receive 1 inch of water per week (if not supplied by natural rainfall). Remove weeds regularly.
Harvest and Storage. When the onion bulbs are as large as they will grow, the tops become weak and fall over. When one half or more of the tops have fallen over, onions are ready for harvest. Pull or dig the onions with tops attached, hang in bunches or spread them out in a warm, airy location out of direct sun, for 2 to 4 weeks, until the tops and necks are dry. You can use a fan to speed drying. Nothing improves the keeping quality of onions more than thorough drying and curing. After the onion tops and necks are thoroughly dry, clip the tops and roots ½ inch from the bulb and place the onions in storage. Onions should be stored in loose buckets or crates or in mesh bags so air can circulate through them. Onions should be kept from 32-40 F in low humidity for best results. A cool, dry basement is good. At warmer storage temperatures, onions to produce sprouts. If storage conditions are too moist, roots may begin to develop. Sweet, mild-flavored onions will keep a shorter period since the bulbs are more succulent. More pungent onions are best for winter storage. Mild-flavored onions should keep 2 to 4 months while other onions should keep a full winter.
Onion Relatives. Several relatives of onions will grow in Kansas. General fertilization and culture conditions are similar.
Sets. Sets are usually used to grow green onions (often called scallions), although they will produce onions for bulbs later in the season. Sets are small onion bulbs that were planted thickly, the previous season, to suppress large bulb development, stored through the winter and offered for sale in the early spring. Sets are usually poorly identified by variety, making it a gamble to know the flavor, use, or keeping quality of the mature bulbs. Place sets 1 to 1 ½ inches deep, close enough to touch each other in a single row or a wide bed planting. When plants are six inches or taller, they can be pulled for green onion to thin until 2 or 3 inches remain between onions grown for mature bulbs.
Plants. Plants are onion transplants grown in the fall or winter in southern areas and bundled in 50 to 100 plants per bunch offered for sale in spring. Onion plants are usually well identified as to variety and can make excellent mature bulbs. Choose healthy, green and fresh transplants and set them 1 to 1 ½ inches deep in rows 12 to 16 inches apart (or wider). Onions should be spaced 2 to 3 inches apart, depending on the size of the mature bulbs.
Seed. Onions can be grown from seed, but seeds are the slowest to develop – usually not ready for harvest until August in most areas of Kansas. Plant seeds early in Late March or early April, using one seed per inch in rows 12 to 16 inches apart. Onion seedling plants are slow to establish, so weed control will be critical in seeded onions.
Fertilization and Watering. Onions have a shallow, poorly developed root system, so regular fertilization and watering is essential. Organic material added to the soil in the fall helps to loosen soils and provides necessary fertility. Regular, uniform watering is essential for high yields and quality. Onions should receive 1 inch of water per week (if not supplied by natural rainfall). Remove weeds regularly.
Harvest and Storage. When the onion bulbs are as large as they will grow, the tops become weak and fall over. When one half or more of the tops have fallen over, onions are ready for harvest. Pull or dig the onions with tops attached, hang in bunches or spread them out in a warm, airy location out of direct sun, for 2 to 4 weeks, until the tops and necks are dry. You can use a fan to speed drying. Nothing improves the keeping quality of onions more than thorough drying and curing. After the onion tops and necks are thoroughly dry, clip the tops and roots ½ inch from the bulb and place the onions in storage. Onions should be stored in loose buckets or crates or in mesh bags so air can circulate through them. Onions should be kept from 32-40 F in low humidity for best results. A cool, dry basement is good. At warmer storage temperatures, onions to produce sprouts. If storage conditions are too moist, roots may begin to develop. Sweet, mild-flavored onions will keep a shorter period since the bulbs are more succulent. More pungent onions are best for winter storage. Mild-flavored onions should keep 2 to 4 months while other onions should keep a full winter.
Onion Relatives. Several relatives of onions will grow in Kansas. General fertilization and culture conditions are similar.
Pest Problems
Onions are not seriously affected by pest problems, but a few can cause reduction in yield.
- Onion Thrips. These tiny, sucking insects cause elongated, white blotches on the leaves as onions develop. General use insecticide will control these pests, they seldom cause death of plants, but severe infestations will reduce yields.
- Bulb and Neck Rots. A soft, sunken area on the top of bulbs can develop in storage or in the field causing the leaves to die. Rapid, thorough drying is the best control.
- Smut and Smudges. A blackish growth on bulbs, just under the skin, indicates this disease, and severe infestations can cause leaf and bulb losses. White varieties are more susceptible. If smut problems develop, rotate to another area the following season.