Growing Onions from Seeds or Sets

How to Grow Onions of All Types

Growing Onions from Seeds or Sets

Reading Time: 6 minutes

Beginners and master gardeners are successfully growing onions. Among the hardiest crops, they are almost foolproof.

What’s your onion level? Are you a novice, praying for a harvest of any kind from your limited experience? Have you graduated up to pony packs? Or are you ready for cipollinis and Egyptian walking onions?

Luckily, onions don’t require much coddling. They resist most pests and repel certain insects from other crops. And, no matter what your gardening level, you can soon be growing onions alongside the masters.

Alliums at Their Best

The generic name “allium” refers to the genus including onions, garlic, scallions, shallots, leeks, and chives. Over 800 species of allium exist, and not all are edible. While some cultures have collected wild varieties, such as the Paiute tribes within the Sierra Nevada mountains, other civilizations have cultivated the edible varieties because of their taste and pungency. Most are strongly flavored, though some can lose their pungency if grown in sulfur-free soil.

Alliums are often referred to as perennials because new bulbs form annually at the space of an old bulb. Growing onions that “walk,” such as bunching or multiplier types, take advantage of this regeneration. Garlic can be started from seed but it’s most commonly planted by separating cloves from a bulb harvested the previous year.

Natural health enthusiasts claim alliums are crucial for disease resistance. They stimulate the lymphatic system, which may allow the body to attack and reject viruses. The tears and runny noses produced by especially pungent onions support these homeopathic claims. In some countries, people drink a tonic made from garlic, honey, and lime juice as a health supplement.

Seeds, Sets and Pony Packs

Growing onions can start out three ways: by seed, by set, or by pony pack.

Onions Seeds: Toward the end of the season, onions send up long, rigid scapes with a blossom on top. If that blossom is allowed to remain and is pollinated, the onion tuber shrinks while seeds develop. Those seeds can be planted early the next year in moist and well-drained soil. Growing onions from seed lengthens the time until harvest by several months. The most difficult way to cultivate onions, it allows gardeners to grow rare or specialty varieties which may not be available in any other form. Growing red onions such as Tropeana Lunga may only be possible by ordering seeds online. Sprinkle seeds within loose, moist medium such as potting soil and just barely cover them. Keep the soil moist but not wet. Once green blades emerge remove any coverings which may have been over the seed trays because the leaves will need room to unfold. Allow the seedlings to grow four to five inches tall. Then gently crumble the soil apart with your hands, separating each seedling, and plant individual onions three to six inches apart, depending on variety.

Onion Sets: Seed companies start onions by seed, let them grow for a few months, then pull them and let them dry. Then the companies pack the tiny onions, which can range in size from the size of a fingernail to larger than a quarter, within well-ventilated containers. Planting onion sets is the easiest way to cultivate them within your garden. Growing onions from sets allows you to harvest within 90 days instead of over 120. Purchase sets from seed companies or garden centers. Plant root-side-down, leaving about an inch of soil above the pointed tops. Space far enough apart that mature onions do not touch. Keep the soil moist. Tiny green spikes should emerge in two weeks or less.

Pony Packs: A balance between seeds and sets, pony packs are containers filled with onion seedlings. Pony packs often allow gardeners to choose rare or specialty varieties. Purchase these in garden centers. Gently remove the entire mass of onions from the plastic cups. Crumble the soil, gently separating the seedlings. If you damage the roots, don’t worry. They’re tougher than they look. Use a spoon to pull a little soil back then insert one onion seedling within the cavity and let soil fall back around it. Water gently until the plants are larger.

Photo by Shelley DeDauw

Long Day vs. Short Day

Do you live in the American South or up where winters get cold and snowy? Growing onions successfully can depend on choosing the right type.

Long day onions thrive in climates with a drastic difference between summer daylight hours and those in the wintertime. If the sun sets around 5 p.m. in December, you need long day varieties. Bianca di Maggio, a long-day cipollini, is sweet and mild.

Closer to the equator, the days stay fairly even: twelve hours of sunlight with a balance of darkness within the tropics. States near the Gulf of Mexico or the southern Californian coast need short day varieties. Try Red Creole for a spicy treat.

Are you confused which to choose? Select intermediate types. Australian Brown is an exceptionally large and flavorful heirloom.

Photo by Shelley DeDauw

Growing Onions

So hardy that tops are often seen peeking through late spring snow, onions can be planted as soon as the ground can be worked. They fare better when temperatures are warmer but a frost won’t damage them. Within zones 5 to 7, gardeners regularly plant onion sets in March and seeds in January.

Whether growing onions from seeds, sets, or pony packs, plant in moist, loose soil. Water gently if tops are still delicate. Mulch as soon as tops are over six inches tall to conserve water. Pull any weeds which may compete for roots space. Fertilizer for onions is high in nitrogen and should be applied three weeks after planting then reapplied every two to three weeks.

If rigid scapes and flowers grow, snap them off to concentrate most of the onion’s energy on developing a thick tuber. Though onions can be pulled and consumed at any time, they are fully mature when the tops fall over and bulbs look like they’re pushing out of the ground.

Cure onions by laying them on dry soil in dry, sunny weather. If it may rain, bring them into a sheltered location. After a few hours, tie or braid tops and hang onion bunches within a warm and well-ventilated location until the outer layers have become papery. Store onions in cool, dry, and dark locations such as basements and root cellars. Contrary to popular belief, onions and potatoes do not store well within the same container.

Companion Planting

Growing onions beside or around certain crops may act as a natural pesticide. Consider growing onions as a border to sensitive garden beds. Since alliums emerge early, in cold weather, they will be high enough to mark perimeters by the time you sow or transplant warm-weather crops. They also provide a barrier against many insects which may attack the other vegetables.

The term “repellent” is widely and erroneously used within the gardening world. Many gardeners believe that a plant which repels insects should repel all insects, such as with the marigold myth. No plant repels all insects; some actually attract certain pests. But companion planting allows you to repel some of the pests which plague your valuable crops.

Onions and other alliums repel rabbits, slugs, aphids, carrot fly, cabbage loopers, and Japanese beetles. This helps plants such as fruit trees, nightshades, brassicas, and carrots. Carrots and tomatoes, in turn, help the onions.

Be aware that onions do not repel all insects and they are certainly not insect-proof. The onion fly uses the plant for food, as does the cabbage moth and turnip moth.

Growing onions among other crops can help you obtain a better harvest. “Intercropping” refers to methods of planting different vegetable types closely together so they can utilize the space without creating competition. Onion tubers grow within a specific formation, round and outward, and the roots only go down a few inches. The tops reach tall and thin, creating little shade for foliage beneath. Gardeners can use this concept to sow daikon radishes in close proximity with onions because daikon roots are long and narrow, with tops spreading wide along the ground. Onion tops would poke up between daikon leaves and the daikon greenery acts as mulch for the onions. Other crops which “intercrop” with onions include lettuce and carrots.

Do not plant onions beside legumes such as peas and beans, as they will stunt the legumes’ growth.

Specialty Varieties

If you’re ready to move past the yellow and white sets sold superstore garden centers, search rare seed websites for varieties to impress your friends.

Cipollini onions are wide, flat, coin-like varieties usually available only as seeds. They taste sweet and mild, looking delightful braided and hanging on a kitchen wall. Available in many types such as the yellow Borrettana Cipollini onion or the tiny Red Marble, which looks like a little crimson coin.

Scallions or “green onions” are actually immature versions of larger onions. Growing onions from seeds or pony packs allows gardeners to harvest scallions just after bulbing begins. In turn, “scallion” seeds will turn into round onions if they are left too long in the ground.

Walking or multiplier onions reproduce at the bulb rather than the seed. Varieties include Egyptian Walking or Red Welsh Bunching Onion. Once a single plant is established, it multiplies with offshoots from the base. Gently separate shoots and either consume like scallions or replant to increase your yield.

Growing onions is a satisfying project for beginning to professional gardeners, with many benefits aside from superb flavor. Easy and hardy, they make an excellent companion to other vegetables.

What do you love about growing onions?

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