Planting onions from small bulbs or “sets” is not the best way to grow large onions for storage. Plants grown from sets often begin blooming in mid-summer and stubbornly refuse to stop. Once that happens, onion bulbs dont increase much in size.
Onion Sets This happens because onions are biennials. The first season they grow leaves and a bulb. The next season they bloom and set seeds. Growing the sets is like having one growing season, even though it’s very short. But it gets the sets ready to reproduce by making flowers before you plant them in the garden. Thus, onion sets are a great way to grow green onions but not the best way to grow onions to store for a long time.
Onions are biennial, which means that plants grown from seeds or transplants don’t bloom the first year. This gives them more time to grow bigger bulbs. It’s now springtime, and many mail-order and garden centers sell onion transplants. You can also grow your own, though.
Growing Onion Transplants Onion transplants can be grown in approximately 10-12 weeks. Sow seeds in late February or early March for planting outdoors in early May. Plant seeds ¾ inches deep in a seed-starting soil blend and keep them evenly moist. Once the seedlings come up, give them bright light from a south-facing window in the sun, or even better, put fluorescent lights a few inches above them and leave them there for 12 to 14 hours a day.
As soon as the garden soil is dry enough to work with and the temperature outside reaches 50° F, move the little grass-like seedlings outside. Onion transplants will tolerate light frosts. Planting as early as possible is important because more leaf growth equals bigger bulbs. In an onion bulb, each leaf forms a layer. The more layers there are, the bigger the bulb is when it’s time to harvest.
Place the seedlings 4 inches apart in wide row plantings. When “wide” rows are used, plants are not lined up one long row, but rather spread out along a row that is 6 to 36 inches wide. Choose a row width that lets you reach both sides easily. This will make it easier to harvest and pull weeds.
Direct Seeding Onions can also be direct seeded. This is a good option if you can’t find your favorite cultivar as a transplant. Plant seeds as soon as the soil can be worked, usually from mid to late March. Wide row spacing also works well when planting onion seeds. Plant the seeds 1/4 – 1/2 inch deep in the soil. Space rows 12-18 inches apart. Once the plants have 5–10 leaves, they can be thinned so that the ones that are left are 3–4 inches apart. The plants that are harvested can then be used as green onions.
Growing On Onions grow best in well-drained soil, 6. 5 pH, with a high level of organic matter. Raised beds, 4-6 inches high, work well to provide good soil drainage if the native soil is heavy. They also need plenty of sunlight, and regular watering. The installation of drip irrigation the length of the rows makes watering easier and more uniform. Don’t be concerned if a large portion of the bulb develops above ground; thats normal for onions.
Onion sets are a popular way for home gardeners to grow onions. But what exactly are onion sets and how are they different from seeds or transplants? This article will explain what onion sets are, how they are grown, their pros and cons, and provide tips for planting them successfully.
What is an Onion Set?
Onion sets are miniature onion bulbs that were grown the previous season. They are typically around the size of a nickel in diameter. Onion sets form when seeds are planted more thickly than normal, resulting in crowded growing conditions. This crowding inhibits full size bulb development, so the onions stop growing early and form sets.
The sets are harvested in late summer and then dried and stored in a dormant state over the winter In the spring, gardeners can purchase bags of onion sets from garden centers, hardware stores, seed catalogs and websites The sets wake up from dormancy and are ready to grow when replanted.
Onion sets are most commonly available in a few popular storage varieties like Yellow, White, and Red. Shallot sets are also sometimes available. When planted in spring, onion sets grow into full size bulbs ready for harvest by mid-summer.
How Are Onion Sets Grown?
Onion sets are produced by commercial growers who sow seeds very thickly in late summer, often in wide rows or beds. The crowded growing conditions trigger the onions to stop enlarging and form small bulbs in just 8-10 weeks.
In late summer or early fall when the foliage dies back, the sets are harvested from the soil. After drying and curing, they are sorted by size, bagged up, and stored in cool, dry conditions over winter. Larger sets 2/3 inch or bigger may be replanted by the grower to produce seed. The smaller sets around 1/2 inch are sold for planting the following spring.
Pros of Planting Onion Sets
Ease and Convenience – No need to start seeds indoors. Just plant the sets directly in the garden.
Earlier Harvest – Sets form bulbs 4-6 weeks faster than plants grown from seeds.
More Reliable Crop – Sets practically guarantee a harvest, even for beginners.
Limited Variety Options – Only the most popular storage varieties available.
Smaller Bulbs – Crowding as sets limits full size bulb development.
Tendency to Bolt – Some sets pre-maturely form flower stalks instead of bulbs.
Tips for Planting Onion Sets Successfully
Follow these tips to get the best results from your onion sets:
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Pick small sets – The smallest sets about 1/2 inch wide produce bigger bulbs than large sets. Avoid sets sprouting green shoots.
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Plant early – Get sets in the ground 3-4 weeks before the last frost. Onions tolerate cool weather.
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Space properly – Allow 3-6 inches between sets depending on final bulb size desired.
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Plant shallow – Bury sets just 1-2 inches deep, tops slightly exposed.
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Fertilize lightly – Too much nitrogen causes excessive leaf growth rather than bulb growth.
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Weed diligently – Onions grow slowly at first, easily overwhelmed by weeds.
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Water thoroughly – Give 1-2 inches per week. Avoid waterlogging the soil.
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Cure well – Allow tops to die down completely before harvesting. Cure bulbs for long term storage.
Why Choose Sets Over Seeds?
Sets offer a major advantage over seeds – earlier harvest. Onions grown from seeds take 3-4 months to produce bulbs. Sets form bulbs in just 8-10 weeks, letting you start enjoying onions sooner.
Sets are also extremely reliable even for beginners. As long as planted properly, sets practically guarantee a harvest, unlike seeds which can be tricky to grow.
The trade-off is that sets limit variety options. Only the most popular varieties are available as sets. By starting seeds there are many more diverse onion types to select from. Seeds also allow growing specific regional varieties suited to local growing conditions.
Should You Buy Onion Sets or Transplants?
Onion transplants offer another option, besides sets and seeds, for an early start on the onion growing season. Transplants are young onion seedlings started ahead of the season and sold in bundles.
Compared to transplants, sets allow earlier planting because there is no threat of cold damage like tender young seedlings. However, transplants generally grow bigger due to less crowding than sets experience.
For most gardeners, sets are quicker and easier to plant directly without any advance preparation. So sets suit beginners best. But transplants offer more choices and potentially larger yields if properly handled.
Storing Leftover Onion Sets
Don’t worry about leftover onion sets. Place any unused sets in a paper bag or stocking. Keep them in a cool, dry spot and they’ll remain viable for fall planting. Stored properly, sets can keep for several months. Replant the sets late in the season for a fall onion harvest.
Enjoy the Convenience of Onion Sets
Onion sets offer gardeners a reliable, low effort way to grow a crop of onions. Just poke them in the ground early in spring and wait for the delicious bulbs to size up. Though limited in variety, their ease of use makes sets a great choice for the impatient or busy gardener. With the right planting and care tips, onion sets will provide a bountiful harvest.
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Green spring onions; by Pixabay.com.
Planting onions from small bulbs or “sets” is not the best way to grow large onions for storage. Plants grown from sets often begin blooming in mid-summer and stubbornly refuse to stop. Once that happens, onion bulbs dont increase much in size.
Onion Sets This happens because onions are biennials. The first season they grow leaves and a bulb. The next season they bloom and set seeds. Growing the sets is like having one growing season, even though it’s very short. But it gets the sets ready to reproduce by making flowers before you plant them in the garden. Thus, onion sets are a great way to grow green onions but not the best way to grow onions to store for a long time.
Onions are biennial, which means that plants grown from seeds or transplants don’t bloom the first year. This gives them more time to grow bigger bulbs. It’s now springtime, and many mail-order and garden centers sell onion transplants. You can also grow your own, though.
Growing Onion Transplants Onion transplants can be grown in approximately 10-12 weeks. Sow seeds in late February or early March for planting outdoors in early May. Plant seeds ¾ inches deep in a seed-starting soil blend and keep them evenly moist. Once the seedlings come up, give them bright light from a south-facing window in the sun, or even better, put fluorescent lights a few inches above them and leave them there for 12 to 14 hours a day.
As soon as the garden soil is dry enough to work with and the temperature outside reaches 50° F, move the little grass-like seedlings outside. Onion transplants will tolerate light frosts. Planting as early as possible is important because more leaf growth equals bigger bulbs. In an onion bulb, each leaf forms a layer. The more layers there are, the bigger the bulb is when it’s time to harvest.
Place the seedlings 4 inches apart in wide row plantings. When “wide” rows are used, plants are not lined up one long row, but rather spread out along a row that is 6 to 36 inches wide. Choose a row width that lets you reach both sides easily. This will make it easier to harvest and pull weeds.
Direct Seeding Onions can also be direct seeded. This is a good option if you can’t find your favorite cultivar as a transplant. Plant seeds as soon as the soil can be worked, usually from mid to late March. Wide row spacing also works well when planting onion seeds. Plant the seeds 1/4 – 1/2 inch deep in the soil. Space rows 12-18 inches apart. Once the plants have 5–10 leaves, they can be thinned so that the ones that are left are 3–4 inches apart. The plants that are harvested can then be used as green onions.
Growing On Onions grow best in well-drained soil, 6.5 pH, with a high level of organic matter. Raised beds, 4-6 inches high, work well to provide good soil drainage if the native soil is heavy. They also need plenty of sunlight, and regular watering. The installation of drip irrigation the length of the rows makes watering easier and more uniform. Don’t be concerned if a large portion of the bulb develops above ground; thats normal for onions.
- Green onions
- White onion sets
- Onions growing in the garden
Planting Onion Sets: What to Watch Out For
FAQ
What is the difference between onion sets and onion plants?
What are onion sets good for?
How many onions are in a set?
What are onion sets?
Sharing is caring! Onion sets are small, dry onion bulbs grown the previous season but not allowed to mature. Grow your own onion sets from seed. It is not difficult, does not require much time, and can put you ahead in both time and money.
What are the substitutes for onions?
A small onion is a good replacement for a traditional onion. Other alternatives include pout onions, celery, grated chives, cilantro, garlic powder, garlic, garlic salt, and onion flakes, which is a dehydrated form of onion and has a mild flavor.
What is an onion set / transplant?
An onion set / transplant is your ticket to getting homegrown onions without all the worry and time. They are basically immature onions that are ready to be planted into your garden for their last bit of growing and maturing before they hit the dinner table. Onion sets/ transplants are a godsend that let us plant and harvest in the same year.
When do onion sets come in a box?
They usually come in a mesh bag or a box depending on where you buy them from. Onion sets are planted about 4-6 weeks prior to freezing temperatures. This gives the bulb some time to sprout before a long winter dormancy. In NYC, hardiness zone 7b, we plant our onion sets in mid to late October.