Success with onions under New Mexico's climatic conditions depends    upon knowing the right varieties to use, and the correct time of the    year to get them started. Listed below are some good guidelines.

Onions are often grouped according to taste. The two main types of onions are strong-flavored (American) and mild (often called     European). Each has three distinct colors; yellow, white and red.

Generally, American onions have smaller bulbs, denser texture, stronger flavor and better keeping quality than European types.
Globe varieties tend to keep longer in storage.

Onion varieties also differ in the number of daylight hours required to make a bulb. If the seed catalog lists an onion as a long-day    variety, it bulbs when it receives 15 to 16 hours of daylight.

Long-day varieties are used in the northern United States to produce    onions in summer. Short-day varieties bulb with about 12 hours of    daylight; they are used in southern areas for winter onion production.

For green or bunching onions, use sets, seeds or transplants in spring. In fall, use Egyptian (perennial tree) and yellow multiplier    (potato onion) sets.

For bulb production, set out transplants in early spring, spacing    them 4 to 6 inches apart and 1 to 2 inches deep in the row. Planting    too early and exposure to cold temperatures causes seed stalk     development. Egyptian tree or multiplier onions should be set in     late October or early November. Plant 4 inches apart in rows 1 to 2 feet apart. Distance between rows is determined by available space  and cultivating equipment.
Onions have shallow root systems and compete poorly with weeds.

Shallow cultivation is necessary; do not mound soil on onions as    this may encourage stem rot. Ensure ample moisture, especially after    bulbs begin to enlarge.

Onions should be harvested when about two-thirds of the tops have fallen over. Careful handling to avoid bruising helps control    storage rots and thorough curing increases storage life.

Onions can be pulled and left in the field for several days to dry, then cured    in a well-ventilated attic or porch for 1 or 2 weeks where they are not in direct sunlight. Tops may be left on or cut off, but leave at least 1 inch of the top when storing.

Here are some tips for onion growing:

Diseases: Neck or stem rot; bulb rot; pink root

Insects: Thrips; onion root maggots

Cultural:   Bulb rot from bruising or insufficient drying; split or double  bulb from dry soil during bulb formation; very small bulb from planting too late or inadequate soil moisture

Days to maturity:        100 to 120 (mature bulbs)

Harvest: Harvest green onions when tops are 6 inches tall and bulbs after  two-thirds or more of the tops have fallen over. Do not waitmore than 1 or 2 weeks after this occurs; allow time for thorough drying before storage.

Approximate yields (per 10 foot row): 0 to 15 pounds

Amount to raise per person: 10 to 15 pounds

Storage: Cool (32°F), dry (65 to 70 percent RH) conditions for 6 to 7 months

Preservation:        Onions can be stored dry or pickled and canned; they freeze well if chopped and covered with water. For fresh storage, maintain good air circulation. An effective storage method is to place an onion in a nylon hose, tie a knot and add another onion. When the hose is filled, suspend it from rafters in a storage area.

Suggested Onion
Varities for New Mexico

Onions, Fall Planted
Early New Mexico                    
Grano                   
Temprano Grano
Hybrid White Bermuda
Texas Grano
Red Hamburger
Granex Hybrid

Onions, Spring Planted               
White, Yellow & Red Globe
White & Yellow Sweet Spanish
Walla Walla Sweet

Onion growing facts
• Light: Sunny (green onions tolerate partial shade)
• Soil: Well-drained loam
• Fertility: Medium-rich
•  pH: 5.5 to 7.0
• Temperature: Cool (45° to 60°F) during development; medium-hot   (60° to 75°F) during bulbing and curing
•  Moisture: Moist, but not waterlogged
•  Planting: Use sets, seeds or transplants in spring for bulbs and green or bunching onions; seeds may be started indoors 8 weeks before setting out; use sets in fall for perennial or multiplier onion types
•  Spacing: Standard - 1 to 4 inches X 12 to 24 inches; wide row- 4 inches X 4 inches in rows up to 2 feet apart; plant close,  then thin; use thinnings as green onions
•  Hardiness: Bulb onions - hardy biennials; green or bunching –  hardy biennials; Egyptian or Perennial Tree and multiplier – hardy perennials
•  Fertilizer: Heavy feeder; apply 4 to 5 pounds of10-10-10 per 100 sq  ft before planting and side-dress 3weeks after trans-planting and again when bulb enlargement begins (2 or 3 tablespoons of 21-0-0 per 10 feet of row)


Tom Dominguez is an agent with the Quay County Extension, NMSU Extension Service. He can be reached by emailing todomingu@nmsu.edu or calling 461-0562.