How to Plant Winter Onion Sets

Onions are planted in the garden from seeds, transplants or sets. Onion sets are actually immature bulbs that grow into either green onions or bulbs. Green onions are the foliage of the onion sets while bulbs are formed once the sets mature. Spring sets are grown mostly for green onions, as warmer weather causes the onion plant to bolt and flower before the bulb is mature. For mature bulbs from sets, plant in fall for winter so the bulbs have time to mature before bolting.

Difficulty: Easy

Instructions

Things You'll Need:

• Compost
• Hoe
• Onion sets
• Shears

1. Prepare a well-drained garden bed in full sun in early fall, approximately twelve weeks before the first frost date in your area. Lay a 2-inch layer of compost over the bed and till it in to a 10-inch depth to improve soil drainage.

2. Plant winter onion sets to a 1 1/2-inch depth in the soil. Space each set 3 inches apart to give the bulbs room to develop.

3. Water the bed thoroughly after planting so that the soil compacts slightly and there are no air pockets. Keep the soil evenly moist at all times, but not soggy.

4. Allow the tops to yellow and fall over naturally, prior or just after the first fall frost. Cut off the tops to within 1-inch of the soil surface.

5. Pull up each onion and brush off excess soil. Spread the onions out in a single layer in a dry, shaded area to cure for one week.

6. Store onions in a cool, well-ventilated room at about 45 degrees F for three or more months. Check stored onions regularly for soft spots and remove any from storage that have developed these for immediate use.

Tips & Warnings

• Plant intermediate or long day varieties of onions if you require a longer storage life, and short day varieties in areas with less autumn sunlight.
• If growing sets for green onions space the bulbs only 1 to 2 inches apart.
• An application of balanced fertilizer before planting is beneficial to the onion plants.
• Only use fully mature compost and remove any dead plants from the onion bed to prevent onion maggots from being drawn to the onion bed.
• Winter sets are often smaller than spring planted onion sets.

References

• Clemson University Extension