Yes, you can grow onions from onions, but the answer depends on what you mean by “onion.” A rooted scallion base can regrow green tops quickly. A small dormant onion bulb, called an onion set, can grow into a harvestable bulb. A whole grocery-store onion can sprout leaves, but it is not the reliable path to a new full-size storage onion.
That distinction matters. We see the same thing on job sites when homeowners ask us to build a small kitchen garden: the planting method, drainage, soil depth, and layout decide whether the bed produces food or just looks good for one season. Onions are not hard, but they are particular. They have shallow roots, they hate weed pressure, and they need the right daylength variety for your latitude.
If you want the short answer, use scallion bases for greens in a few weeks, use onion sets for an easy homeowner bulb crop, and use transplants or seed if your goal is large storage onions. Build or prepare a sunny, well-drained bed, plant shallow, keep moisture steady, and cure mature bulbs before storage.
Start Here: Pick the Right Onion Method
The biggest mistake is treating green onion scraps, onion bottoms, sets, transplants, and seed as if they are the same project. They are not. They have different costs, timelines, yields, and failure points.
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| Method | Best for | Typical timeline | 2026 cost range | Reliability |
|---|---|---|---|---|
| Rooted scallion or green onion bases | Fast green tops | About 2-4 weeks for usable greens | Often free from kitchen scraps | Good for greens, poor for bulbs |
| Onion sets | Easy small-to-medium bulbs or green onions | Roughly 90-100 days for dry bulbs | About $7.71-$14.25 for 80 sets, or $0.10-$0.18 each | Good, if sets are small and planted correctly |
| Onion transplants | Larger bulbs and storage onions | Often planted in spring or fall depending on region | Group pricing around $4.50-$5.50 per bunch; mail-order retail may be higher | Very good when matched to region |
| Seed | Best variety selection and lowest per-plant cost | Start indoors 8-10 weeks before transplanting | About $3-$6 per packet, plus starting supplies | Good, but slower and more hands-on |
| Whole grocery-store onion or onion bottom | Experimenting with sprouts | Unpredictable | Cost of the onion | Low for full-size bulbs |
For a homeowner who wants a dependable garden crop without nursery-level work, onion sets are the practical middle ground. For storage onions worth keeping through winter, transplants or seed usually perform better because you can choose the correct variety and avoid oversized sets that bolt.
Can You Grow a Full Onion from a Grocery-Store Onion?
You can make a grocery-store onion sprout. You may get green shoots. You may even get several divisions if the bulb has multiple growing points. But that does not mean you will grow a good new onion bulb.
Bulb onions are biennial plants. In plain terms, they usually spend one season building a bulb and the next season trying to flower and set seed. A mature grocery-store onion has already completed the bulb-building stage. Once replanted, it often wants to send up foliage or a flower stalk instead of making a clean, dense bulb. It may also rot because the cut base or stored bulb tissue is sitting in wet soil.
There is another issue: daylength. Onion varieties form bulbs when daylight reaches the right range. If the grocery onion came from a region or variety that does not match your climate, it may grow tops but never size up properly. That is why we do not recommend grocery bulbs as the main plan for a raised bed. Use them as a learning experiment, not as the crop you are counting on.
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Choose the Right Onion Type for Your Region
Onions respond to daylength. This is one of the places where a little planning saves an entire season. If the variety does not match your latitude, the plant can put on leaves at the wrong time, bulb too early, or fail to bulb well at all.
Short-Day Onions
Short-day onions begin bulbing at roughly 10-12 hours of daylight. They are generally suited to southern states and mild-winter regions. In many southern areas, they are planted in fall or winter and harvested the following spring or early summer. Examples vary by supplier, so match the variety to your local extension guidance rather than buying only by color.
Intermediate-Day Onions
Intermediate-day onions bridge the middle latitudes of the country. They are often a good fit for areas that are neither deep South nor far North. If you live in a transition zone, intermediate-day varieties can be more forgiving than forcing a long-day or short-day type into the wrong climate.
Long-Day Onions
Long-day onions need longer summer days and are generally suited to northern states. They are commonly planted in early spring as soon as soil is workable and harvested in summer. These are often the better choice for northern gardeners who want storage onions.
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Build or Prepare the Bed Before You Plant
Onions have shallow root systems, so they depend heavily on the top few inches of soil. Compacted clay, standing water, and weed pressure will hurt them fast. On our landscape and exterior projects, we treat a productive garden bed the same way we treat a walkway base or drainage repair: the hidden preparation matters more than the surface finish.
Sun and Location
Choose a spot with full sun. Six hours is a working minimum, but 8 or more hours is better for bulb development. Avoid low spots where water sits after a storm. If your yard has heavy clay, build raised rows or a raised bed instead of trying to force onions into soggy native soil.
Raised Bed Dimensions That Work
A practical onion bed is 3-4 feet wide so you can reach the center from both sides without stepping into the soil. A 4-by-8-foot bed gives you 32 square feet of growing area, which is enough for a useful onion crop without taking over the yard. Keep walkways wide enough for a wheelbarrow; 24 inches is tight but workable, while 30-36 inches is more comfortable.
For height, 8-12 inches above grade is enough for most onion beds if the underlying soil drains reasonably well. If you are building over compacted clay, tree roots, or poor fill, 12-18 inches gives you more control. Taller accessibility beds cost more because they require more structure and soil, but they can be worth it for homeowners who do not want to kneel.
Soil Depth and Volume Math
A 4-by-8-foot bed filled 12 inches deep takes 32 cubic feet of soil, or about 1.19 cubic yards. Filled 8 inches deep, it takes about 21.3 cubic feet, or 0.79 cubic yards. That math matters because bagged soil is convenient but expensive.
| Bed size | Fill depth | Soil volume | Bagged soil estimate | Bulk soil estimate |
|---|---|---|---|---|
| 4 ft x 8 ft | 8 in. | 21.3 cu ft | About 15 bags at 1.5 cu ft each | About 0.79 cu yd |
| 4 ft x 8 ft | 12 in. | 32 cu ft | About 22 bags at 1.5 cu ft each | About 1.19 cu yd |
| 3 ft x 6 ft | 10 in. | 15 cu ft | About 10 bags at 1.5 cu ft each | About 0.56 cu yd |
In 2026, bagged raised-bed soil commonly runs about $5.65-$6.65 per cubic foot before sales based on big-box pricing. A 4-by-8 bed filled 12 inches deep can easily use $180-$215 in bagged soil alone. Bulk garden soil from local suppliers commonly runs about $69-$85 per cubic yard before delivery, but the delivery fee and minimum order can change the real price. For one small bed, bags may be simpler. For multiple beds, bulk soil usually wins.
Soil Texture, pH, and Amendments
Use loose, well-drained soil with organic matter mixed through the top 6-8 inches. A pH around 6.0-6.8 is a good target for onions. If you are unsure, a soil test is better than guessing with lime or fertilizer.
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Rank #2
- Includes a colorful mix of red, white, and yellow onion sets with intermediate-day, day-neutral, and long-day varieties for USDA Zones 3–10.
- HARVEST AT ANY STAGE: Pick tender green onions early in the season or let bulbs fully mature into full-size onions ideal for cooking, storage, and long-term use.
- Simply plant sets 3–6 inches apart in loose, well-drained soil and water consistently for a productive harvest.
- Fall Planting: Plant onion sets in the fall to overwinter them for an early summer harvest the following year
- Easy to Grow: Boiler Onion is known for its hardy nature and ability to thrive in a variety of climates and soil conditions.
Do not fill an onion bed with straight compost, heavy topsoil, or cheap unscreened fill. Compost is an amendment, not a complete structural soil. Heavy topsoil can settle into a dense slab after a few rains. A good raised-bed blend should hold moisture without staying saturated.
How to Regrow Green Onions from Onion Scraps
This is the easiest method, and it is the one that actually matches what many people mean when they ask how to grow onions from onions. It is best for scallions or green onions, not storage bulbs.
Indoor Water Method
Save the white base of a green onion with roots attached. Leave about 1-2 inches of white stem above the root plate. Set the bases upright in a glass with enough water to cover the roots but not drown the entire stem. Put the glass in bright light and change the water every couple of days.
You can usually start trimming new green tops within a few weeks. The growth will slow over time because water alone does not replace all the nutrients the plant used to have in soil. This is a good kitchen trick, not a permanent production system.
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Repair common Windows errors and clear accumulated junk for a smoother, more stable PC - no reinstall needed.Free scan · no reinstallSoil Method
For better growth, plant rooted scallion bases in potting mix or a garden bed. Set them about 1 inch deep and 1-2 inches apart if you are harvesting greens. Keep the soil evenly moist, not soggy. A window box or 8-10-inch-deep container is enough for greens.
A small container setup can cost about $15-$45 if you already own basic tools. That covers a pot or window box, potting mix, and either onion sets or saved scallion bases.
How to Plant Onion Sets for Bulbs
Onion sets are small dormant bulbs. They are easy to handle, easy to space, and forgiving for new gardeners. In 2026, big-box online prices show roughly $7.71-$14.25 for 80 bulbs, depending on variety, supplier, organic status, shipping, and local pricing. That puts most sets around $0.10-$0.18 each.
Examples found in 2026 included 80-bulb bags listed around $12.62 for white onion sets, $8.72 for red onion sets, $7.71 for Sturon sets, and $14.25 for Stuttgarter Reisen sets. Local availability changes by region and season, so buy early if you want a specific variety.
Pick Smaller Sets for Dry Bulbs
For dry bulb onions, smaller sets are usually better. Large sets may seem like a head start, but they are more likely to bolt, meaning they send up a flower stalk. Once an onion bolts, bulb quality drops and storage life suffers. Use larger sets for green onions, where you will harvest early before bolting matters as much.
Planting Depth and Spacing
Plant onion sets about 1 inch deep. The pointed end goes up. Do not bury them like potatoes. Bulb onions expand near the soil surface, and deep planting can reduce bulb size or encourage rot.
For dry bulbs, space sets 3-4 inches apart. Rows are commonly spaced 12-18 inches apart, though some retail guides allow 12-24 inches. In a raised bed, you do not need wide tractor-style rows. A grid with 4 inches between plants in all directions can work if you keep the bed weeded and watered. At 4-inch spacing, a 4-by-8-foot bed has room for a substantial crop, though edge spacing and access paths reduce the theoretical maximum.
For green onions, you can plant closer, often 1-2 inches apart, because you harvest before the plants need room to form mature bulbs.
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When to Plant
In many northern and middle-latitude regions, plant onion sets in early spring as soon as the soil is workable. The bed should not be frozen, muddy, or saturated. In mild southern climates, short-day onions may be planted in fall or winter depending on local guidance. If your region has hot summers, timing matters because onions need leaf growth before bulbing begins.
Watering, Mulching, and Maintenance
Onions are shallow-rooted, so inconsistent moisture shows up quickly as small bulbs, stress, or premature bulbing. The goal is steady soil moisture, not wet feet.
Use drip irrigation or a soaker hose when possible. It keeps water near the root zone, reduces waste, and keeps foliage drier than overhead watering. On small beds, a simple 1/2-inch drip mainline with emitters or a soaker hose on a hose-end timer is usually enough. Check the soil by hand. If the top inch is dry and the bed below is starting to dry out, water.
Mulch can help, but keep it light. A thin layer of clean straw or shredded leaves can reduce weeds and slow evaporation. Do not pile mulch directly over the bulbs. Onions need room to expand near the surface.
Weeding is not optional. Onions compete poorly because their leaves are narrow and their roots stay shallow. Pull weeds when they are small so you do not disturb onion roots later. This is one reason narrow beds matter: if you can reach every plant from the walkway, you are more likely to keep up with maintenance.
Rank #3
- 60-80 Onion Sets or Bulbs
- Onion sets are small "baby" onions (bulbs) that are used to grow green onions or dry onions.
- They are planted in early spring or Fall and in 4 to 5 weeks you will have green onions. If left to fully mature, you will have dry onions in late July or early August.
- Height: 12 - 18 inches. Spacing: 2 - 4 inches apart.
- Depth: Plant sets 1 - 2 inches deep and 2 - 4 inches apart.
Why Onion Bottoms and Whole Bulbs Often Fail
There is nothing wrong with experimenting, but set your expectations correctly. A cut onion bottom has stored energy and may push new shoots. That does not mean it has the structure, disease resistance, or growth stage needed to produce a market-quality onion.
Common failure points include rot from wet soil, flowering instead of bulbing, multiple weak shoots competing inside one old bulb, and poor daylength match. Grocery onions may also be treated, stored, or selected for shipping and shelf life rather than backyard regrowth.
If you want to try it anyway, use a firm onion with visible root plate tissue. Cut the bottom section about 1 inch thick, let the cut surface dry for a day, and plant it shallow in loose soil with the root side down. Keep it barely moist until growth appears. If it smells sour, collapses, or gets mushy, discard it. Do not build your seasonal planting plan around this method.
Harvesting and Curing Storage Onions
Green onions can be harvested whenever the tops are large enough to use. For sets planted as green onions, that may be within 2-4 weeks. For scallion scraps, expect roughly a month for meaningful regrowth depending on light, temperature, and whether they are in water or soil.
Dry bulb onions take longer. Sets commonly need about 90-100 days for summer harvest. Weather, variety, planting date, and spacing can move that number.
For storage onions, harvest when about half the tops have fallen over and started to dry. Do not wait until every plant is completely dead if rain is coming or the soil is staying wet. Lift bulbs gently with a garden fork instead of yanking hard enough to tear the neck.
Curing is what turns a fresh onion into a storage onion. Lay bulbs in a warm, dry, well-ventilated place out of direct rain. A covered porch, open garage, shed with airflow, or shaded rack can work. Keep them in a single layer if possible. Cure until the necks are dry and the outer skins are papery. Then trim tops to about 1 inch above the bulb unless you are braiding suitable varieties. Store only firm, undamaged onions. Use thick-necked, bruised, or bolted onions first because they will not keep as long.
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A small onion bed is simple, but it still sits in a real yard with utilities, drainage, property lines, HOA rules, and sometimes city right-of-way requirements. We check these items before building because moving a finished bed is wasted labor.
Utility Marking and Digging
Call 811 before digging posts, trenching irrigation, building a fence, or setting a greenhouse foundation. A shallow raised bed placed on grade may not need deep excavation, but edging stakes, trellis posts, sleeves, drainage runs, and irrigation tie-ins can cross underground utilities.
Drainage and Setbacks
Do not solve one drainage problem by sending water into a neighbor’s yard, against the house foundation, or across a walkway where it can freeze. Keep beds away from siding where constant irrigation splash can create moisture problems. If a bed is near a basement wall, crawlspace vent, or low threshold, manage runoff first.
Right-of-Way, HOA, and Permit Triggers
A basic raised garden bed in a private backyard usually does not require a building permit, but local rules vary. Front-yard beds, planting strips, corner lots, and right-of-way areas can be regulated. Some cities require permits or approvals for planting in the right-of-way. HOAs may control bed height, materials, visibility, fencing, compost bins, and irrigation equipment.
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Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.What a Realistic Onion Bed Costs in 2026
A small onion project can be cheap if you use existing soil and saved scallion bases. It can also become a few-hundred-dollar build once you add a raised bed, soil, irrigation, fencing, and delivery.
| Project type | Typical scope | Estimated 2026 cost |
|---|---|---|
| Kitchen scrap regrow | Scallion bases, water glass or small pot | $0-$15 if using items on hand |
| Small container onion setup | Pot/window box, potting mix, sets or scraps | About $15-$45 |
| Simple in-ground planting | Onion sets, compost, basic fertilizer if needed | About $20-$75 |
| 4 x 8 raised bed | Bed frame, soil, compost, onion sets | Roughly $100-$350+ depending on materials and soil source |
| Contractor-built garden area | Grading, drainage correction, bed construction, irrigation, fencing or access paths | Varies widely; labor, drainage, materials, and site access drive cost |
Bagged soil is often the budget breaker. A 4-by-8 bed filled 12 inches deep needs about 32 cubic feet. At $5.65-$6.65 per cubic foot, soil alone can approach or exceed $200 before the bed frame. Bulk soil may cost less per cubic foot, but delivery and minimum order size matter.
When to DIY vs. When to Hire a Pro
Planting onions is a good DIY job. Building a simple wood or metal raised bed is also reasonable for a handy homeowner with a level, drill, saw, shovel, and a free weekend. The DIY route makes sense when the site is flat, drainage is already decent, utilities are not involved, and the bed is small enough to build without equipment.
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Rank #4
- "Candy" Super Sweet Onion Sets or Bulbs
- "mid-day" or day-neutral variety
- This means that it can be grown just about anywhere from the far north to the deep south
- huge, savory yellow onion, with thick, succulent flesh and a delicious flavor both sharp and sweet!
- Grown in the USA
For homeowners planning more than one bed, we usually recommend laying out the whole garden before building the first box. Plan bed widths, walkway widths, hose access, sun exposure, compost location, gate swing, wheelbarrow access, and future fencing. A clean layout costs less to build once than to revise after the first season.
Common Onion-Growing Mistakes
The first mistake is expecting a grocery-store onion bottom to produce a full-size onion reliably. It may sprout, but it is more likely to give you greens, a flower stalk, rot, or a cluster of weak divisions than a good storage bulb.
The second mistake is planting too deep. Onion bulbs need to expand near the surface. About 1 inch deep is enough for sets. If you bury them several inches down, you are working against the plant.
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The third mistake is choosing the wrong daylength type. A short-day onion in the far North or a long-day onion in the deep South can disappoint even if the soil and watering are good.
The fourth mistake is using oversized sets for storage onions. Big sets can bolt. Smaller sets are usually the better choice for dry bulbs, while larger sets are fine for green onions.
The fifth mistake is letting weeds get established. Onions do not shade the ground well, and they do not compete aggressively. Keep the bed clean from the start.
The sixth mistake is skipping curing. Pulling a mature onion and putting it straight into storage is how you lose bulbs. Cure them warm, dry, and ventilated first.
Bottom Line
Growing onions from onions works when you choose the right version of the project. Regrow scallion bases for quick greens. Plant onion sets for an easy bulb crop. Use transplants or seed for the best shot at large storage onions. Do not rely on whole grocery-store onions unless you are experimenting.
Give onions full sun, loose well-drained soil, shallow planting, steady moisture, and the correct daylength variety. If your native soil is compacted or wet, a 3-4-foot-wide raised bed, 8-12 inches deep, is usually a better investment than fighting poor ground all season. Build the bed like you expect it to last, plant the onions like shallow-rooted crops, and cure the harvest before you store it.
Frequently Asked Questions
Can you grow a full onion from a grocery-store onion?
Sometimes it will sprout, but it is not reliable for full-size bulbs. A grocery-store onion is already a mature bulb and may rot, bolt, or grow greens instead of forming a good new storage onion.
What is the difference between onion sets, onion plants, and onion scraps?
Onion sets are small dormant bulbs planted for green onions or bulbs. Onion plants are transplants grown from seed and are often better for large storage onions. Onion scraps, such as rooted scallion bases, are best for regrowing green tops.
How deep should onion sets be planted?
Plant onion sets about 1 inch deep with the pointed end up. Onions should not be buried deeply because bulb expansion happens near the soil surface.
How far apart should onions be planted in a raised bed?
For dry bulb onions, space plants about 3-4 inches apart. For green onions, spacing can be closer, around 1-2 inches, because they are harvested before mature bulbs need room.
Why did my onions grow tops but no bulbs?
Common causes include the wrong daylength variety for your region, planting too late, too much shade, drought stress, overcrowding, or using grocery-store onions that were not suited for regrowing.
Do I need a permit to build a raised garden bed or small greenhouse for onions?
A simple backyard raised bed often does not need a permit, but rules vary. Check local requirements for front-yard beds, right-of-way planting, greenhouses, sheds, fences, irrigation tie-ins, electrical work, retaining walls, and HOA restrictions.
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