Learning Download: How to Grow Onions
From Seed to Harvest: A guide to growing onions.
A way to jazz up any dish is to add some onions to it. Onions can be grown from seed or from sets, which are immature onion bulbs. There are more opportunities for gardeners if onions are grown from seed, and the outcome is rewarding. There are different kinds of onions, such as short-day onions which grow best in the south and long-day onions which grow best in northern climates. Pick the correct variety for your garden.
Onions need a long growing season, so begin them indoors as early as two months before the last frost. Plant seeds 1/4 inch deep in flats filled with potting mix. Add a plastic top to retain moisture until the onion sprouts.
Once sprouted, remove the plastic. Prior to transplanting, amend the soil with compost. When the transplants are about the size of a pencil, move them to the garden. Plant transplants 4 inches apart. Onions do best in a soil with a pH of 6.0 to 6.5 and in full sun. Water the onions frequently as they have shallow roots and require consistent moisture.
Onions are ready to harvest when the green tops flop over, but they can also be harvested quite early as green onions. For the full onion, once the tops flop over, wait for a dry day to complete the harvest. Pull the bulbs and then place them in a warm, dry location out of direct sun and away from the soil to cure, which can take up to three weeks. Once they have cured, cut back the foliage and store in a cool, dry location.
What onions crave:
Upon planting, add compost to the soil, but since onions are heavy feeders they will grow best if fertilized throughout their growth. Also, add a timed-release granular 10-10-10 or 12-12-12 fertilizer to spread in the soil. Using a nitrate-based fertilizer will make the onions sweeter at harvest.
Where to buy onion seeds:
You can find many different kinds of onion seeds, including red, white, yellow and sweet onions at Urban Farmer.
Learning Download: Onion Comparison Chart
Onion Comparison Chart
|Day Length||Color||Variety||Days||Available in Organic||Disease Resistance|
|Short||Yellow||Texas Early Grano 502 PRR||110||Yes|
|Short||Yellow||Texas Early Grano**||110||Yes||Yes|
|Long||Yellow||Yellow Sweet Spanish**||115-130|
|Long||White||Ailsa Craig Exhibition**||110||Yes|
|Long||White||Walla Walla Sweet**||115|
|Long||White||White Sweet Spanish**||115|
*All American Selection Winner