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Growing Onions From Seeds
Transplants and Sets

Photo of growing onions Growing onions from sets
is the easist method

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Growing Onions

Onions are a member of the Alliaceae family along with garlic, chives, leeks and shallots and are usually categorized according to taste with different varieties of onions having either, a pungent smell and taste, or are quite sweet.

Onion bulbs can be either round or oblong and are composed of concentric layers. The size of an onion bulb will depend on the number and size of the leaves of the mature bulb, for each leaf there will be a ring of onion.

Most onions are biannual but there are a few varieties that are perennial, Potato/multiplier onions and Egyptian walking onions are 2 such varieties. Each onion type has three distinct colors - yellow, white, and red.

More importantly for anyone wishing to grow onions is the day length for the different varieties. Onions begin to form a bulb when the hours of daylight reach certain levels.

Onion varieties that are long day onions begin to form a bulb, when there is 14-16 hours of daylight and grow best in the Northern summers, north of the 36th parallel.

Onions varieties that are short day onions will begin to bulb when there is 10 - 12 hours of daylight hours and grow best in southern summers, south of the 36th parallel.

Quick Reference Guide

Veggie Garden Dairy
Vegetable Onions
Also Known As
Botanical Family - Alliaceae, Genus - Allium, Species - A. cepa
Plant Type Cool season - biennial - root vegetable
Frost Tolerance Hardy
Planting Position Sunny - Will tolerate some shade throughout growing season - requires a minimum of 4-6 hours of direct sunlight daily.
Seed Viability 1 year
Germination 10-14 days at 40-80 F (4-27 C)
Growing Temp 50-70 F (10-21 C)
Seed to Transplant 8-10 weeks
Planting Method Direct sow seed - seedling transplants - onion sets
When to Plant Fall or Spring
Time to Plant As soon as 2 - 4 weeks before the average date of the last 32 F (0 C) freeze in the spring in your area but not before soil temperatures are consistently 40 F (4 C) and above.
Seed Sowing Direct sowing onion seeds - 1/2 inch (12 mm) deep - 1 inch (25 mm) apart in rows 10 inches (25 cm) apart - thin to 4 inches (10 cm) apart in row
Plant Spacing Plant onion sets and transplants - 1 inch (25 mm) deep - 4 inches (10 cm) apart in rows 10 inches (25 cm) apart.
Soil Conditions Well drained - Low to moderate organic matter - Medium fertility
Fertilizer Medium fertilizer needs, 3-4 quarts per 100 sq feet (3.3-4.4 liters per 9.3 square meters) preplanting of all purpose organic fertilizer 5-5-5, same rate for each side dressing.
When to Fertilize 2 weeks before sowing or transplanting - side-dress when the bulbs begin to swell
Days to Harvest 100-120 days - depending on conditions and variety

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