How Deep Do You Plant Onion Sets?

Growing onions in your yard is an easy and rewarding experience. As a vegetable, they may be cultivated for their greens and their bulbs.

Easy to grow onions may be found in your garden. It’s best to grow them in a well-drained, slightly acidic, fertile soil that gets full sunlight. Organic matter, such as compost, may be added to heavy soils to make them more fertile. 

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How Deep Do You Plant Onion Sets

Onions demand a greater fertility level than most other vegetables. Using an all-purpose garden fertilizer, such as 10-10-10, apply 1 to 2 pounds per 100 square feet of soil and rake it in. Sidedress with more fertilizer four to five weeks after planting.

Using an all-purpose garden fertilizer, apply 1 pound every 100 feet of row. The fertilizer should be applied in a thin band approximately 2 to 3 inches from the base of the onion plants.

Photoperiod or day duration is a critical factor in the growth of onions. Both photoperiod and temperature are important in determining bulb morphogenesis. It is easier for plants to produce leaves and roots while it is still cold and dark outside. 

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During a given amount of daylight, the bulb starts to develop For short-day, intermediate-day, and long-day onion types to begin producing bulbs, they must get between 11 and 14 hours of sunlight. 

Gardeners in Iowa and the upper Midwest should stick with long-day cultivars. Iowa short-day cultivars begin to bulb while the plants are little and produce smaller bulbs. If long-day cultivars are planted in late April in Iowa, little bulbs may also be anticipated.

Onions may be produced from seeds, sets, or plants. The manner of planting is determined by factors such as cost, usage, availability, and convenience of installation.


When little onion bulbs have been collected and kept throughout the winter in sets, they are ready to be supplied to garden centers in the early spring. A certain onion variety is not always in stock for the consumer to choose from. Red, white, and yellow onion sets are available for purchase. 

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The taste, usage, and storing quality of onions produced from sets might vary greatly since the variety is unknown. In advance of planting, sort the bulbs into two categories based on diameter: those less than a nickel in diameter and those more in diameter. 

When a bigger set is planted, it is more likely to bolt (grow a blossom stalk) and produce smaller bulbs. Green onions should be grown in bigger groupings. The smaller groups may be allowed to grow into mature onions.

Whenever the ground can be handled in the early spring, the plant establishes. Rows should be spaced 12 to 15 inches apart, with the spacing between the sets being 1 to 1 1/2 inches deep after planting. Plant the sets 2 to 3 inches apart for dried onions. For green onion sets, you may plant them a lot closer together.

Onion Planting Time

  1. Spring and October are good times to grow onions. For the most part, you should plant onion sets outside when it is chilly but not freezing.
    • At least four to six weeks of warm weather are required for an autumn onion crop to become established in the ground. In the winter, they’ll be dormant and ready to sprout when the spring comes.
    • Onion seeds should be planted as soon as the ground can be worked, which is normally in March or April in areas that had a harsh winter. Ideally, you should plant your onions when the temperature is above 28°F (-2°C) outside.
  2. It’s a terrific way to get a head start on next year’s onions by planting them now. Make sure your plants have a robust root system by planting them in warm, fall soil. Crops go into hibernation when the weather becomes colder in the fall and winter Early spring brings the onions back to life as temperatures rise and the ground thaws.
  3. Starting onions from seed approximately six weeks before planting them in the garden is a good idea. At least 50°F (10°C) is required for onion seeds to germinate.
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The Soil Preparation Phase 

Before planting onions, it is best to add 10-20-10 fertilizer or 1 1/2 inches of compost to the soil. Using a half-cup of fertilizer for every ten feet of row, fill the trench with 4 inches of soil and onion sets, then add another 2 inches of soil.

Planting Onion Sets

  1. Buying onion sets that are less than 3/8-inch wide is a necessity. Smaller cultivars should be used to prevent stiff necks and premature seedling emergence.
  2. When planting onion sets, space them between 2 and 6 inches apart.
  3. 4 to 5 inches apart in 12 to 18-inch rows is the ideal spacing for larger transplants.
  4. Set the bulbs upright with the point facing up and don’t bury them more than an inch below the surface. The bulb development of onions can be affected if they are planted too deep
How Deep Do You Plant Onion Sets

When And How To Harvest Onions 

  1. Most spring-planted onions can be harvested by the middle of summer.
  2. When onions produce flower stalks, they’ve finished growing and should be removed. Although these onions won’t last long, they can be used in recipes right away.
  3. It’s time to harvest onions when the tops (foliage) turn yellow and fall over. You can speed up the ripening process by bending or even stomping on the foliage.
  4. By loosening the soil around the bulbs, you can dry them out.
  5. During a dry spell at the end of summer, the best time to harvest fully mature onions is. Before it has time to dry, a wet onion will spoil in storage. In the fall, mature onions may go bad if the weather is too cool.
  6. At this point, remove the onions from the heat and allow the bottoms to caramelize. To avoid rot, treat any blemishes with utmost caution.
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As a result of their speed and ease of planting, we prefer onion sets over onion seeds. Sets of small onion bulbs are only meant to be used in the home garden. A few weeks ago, the bulbs were ready to be harvested.

There is no risk of frost damage when planting onion sets, as opposed to onion seeds or transplants.

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