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Onion Sets vs. Onion Plants

Onions are cool-season vegetables known for adding flavor to dishes. In areas with mild winters, onions can be grown as a winter crop; otherwise, they are planted in the spring. Onions form bulbs based on the length of daylight. You can start onions from either sets or plants, each having its benefits.

Onion Sets
Onion sets are small, dry bulbs that were grown the previous year. They are easy to plant and grow. Simply push the sets into damp soil until just the top shows, and they will start growing. Sets are usually sold in yellow, white, or red varieties without specific names. Round sets will produce flat onions, while tear-shaped sets will produce round onions. Larger sets are good for green onions, while smaller ones will form bulbs.

Onion Plants (Slips)
For larger, firmer bulbs, onion plants are a better choice. These are grown from seeds in the same year they are sold. Onion plants typically come in bundles. To plant, dig a shallow trench, place the onion plants about an inch deep and four inches apart, then cover with soil and water. In North Texas and Southern Oklahoma, onions are planted in January or February.

Planting Onions

• Timing: Plant in January.
• Soil: Use loose, well-drained soil in raised beds or directly in the ground. Ensure the soil is 8-10 inches deep and mix in a 10-20-10 fertilizer into the top 3-4 inches.
• Sunlight: Onions need about 10 hours of full sunlight daily.

Bolting
Onions are biennials, meaning they grow leaves and bulbs one year and flowers the next. Bolting occurs when an onion sends up a flower stalk due to temperature changes. This results in a smaller bulb with a flower stem in the middle, reducing its storage life. Since sets are older, they are more prone to bolting compared to plants.