Crops › Bulb Onion
How to grow Bulb Onion
in the US
Sow March to April, plant out May, harvest June to August. About 120 days from seed to plate.
Shown for zone 6. Zone table further down.
Growing your own bulb onions, it's one of those real satisfying jobs, you know. They're a proper staple in the kitchen, and nothing beats pulling up a row of your own from the ground. It's a medium difficulty crop, but with a bit of care, you'll be chuffed with the harvest.
Sowing
Now, getting these started from seed is the way to go, as you rarely see them as plug plants. The key is timing, and that really depends on your USDA zone. If you're in a colder spot like Zone 3 or 4, you're looking at April or May. Zones 5-7 can sow February to April, while Zones 9-10 can go as early as January or even late in the year. Sow seeds about half an inch deep, either indoors in trays for transplanting later, or directly into the ground once the soil warms up. Give them about an inch spacing in the rows to start with.
Growing on
If you started your seeds indoors, once they're big enough to handle, about three or four inches tall, you'll want to prick them out and give them a bit more space in their trays. Then, before they go into the ground permanently, you've got to harden them off for a week or two – gradually getting them used to the outside weather, you know. Plant them out about four to six inches apart in rows that are a foot apart, once all danger of hard frost has passed for your area.
Looking after it
Onions like consistent moisture, especially when they're bulbing up, so give them a good drink if it's dry. Weeding is proper important too; they don't like competition one bit from other plants trying to steal their nutrients. A bit of general purpose feed can help them along if your soil's not the richest, but don't go mad with nitrogen late in the season, or you'll get more leaf than bulb.
What goes wrong
To be honest, onions can get a few issues. Onion maggots are a pain, so try to rotate where you plant them each year. Thrips can cause silvery streaks on the leaves, and downy mildew can be a problem in damp conditions, making the leaves go yellow and fuzzy. Good airflow helps with that. Keep an eye out and act quickly if you spot anything.
Harvest
You'll know your bulb onions are ready when the tops start to go yellow and flop over, usually around 120 days from sowing. This is typically July through September for many zones. Pick a dry day, gently lift them out of the soil, and then let them dry or "cure" in the sun for a week or so, or in a well-ventilated spot. Once the outer skins are dry and papery, snip off the tops and roots. Store them in a cool, dry place; some types keep longer than others, but most will last a good while.
I always try to get my onion beds ready well in advance, digging in some good compost, because they proper love a rich, well-drained soil, and it saves you a job later.
Dates for your plot
Type your zone and the plant-out advice shifts to your frost dates.
Varieties, and whether the club would grow them again
| Variety | Club verdict |
|---|---|
| Walla Walla Walla Walla is a proper good maincrop onion, known for its sweetness. It's a reliable performer, so great if you're after a dependable crop for cooking or fresh eating. | No club votes yet |
| Candy Candy is a cracking maincrop onion that you can sow directly outside. It's a reliable performer, offering sweet, mild bulbs perfect for a range of dishes. | No club votes yet |
| Patterson Patterson is a super reliable maincrop onion, perfect for indoor starting. It's known for strong, firm bulbs that store really well through the winter. | No club votes yet |
| Redwing Redwing is a lovely red maincrop onion you can sow straight into the ground. It's a reliable performer, giving you good-sized, firm bulbs with a nice color. | No club votes yet |
| Red Zeppelin Red Zeppelin is another excellent red maincrop onion, best started indoors. This variety is a reliable performer, yielding beautiful, dark red bulbs that keep well. | No club votes yet |
| Texas Early Grano Texas Early Grano is an early maturing variety, great if you're keen to get a harvest sooner. You can sow these directly outside, and they produce nice, mild bulbs quickly. | No club votes yet |
| Yellow Granex Yellow Granex is a reliable maincrop onion, ideal for starting indoors. It produces sweet, mild bulbs that are perfect for fresh eating and quick use. | No club votes yet |
| Sierra Blanca Sierra Blanca is a cracking white maincrop onion, perfect for direct sowing. It’s a reliable performer, giving you crisp, mild bulbs that are great for salads. | No club votes yet |
| Ailsa Craig Ailsa Craig is a classic maincrop onion, best started indoors, and a proper favorite of mine. It's a reliable performer, famous for producing really large, exhibition-quality bulbs. | No club votes yet |
| Copra Copra is a fantastic maincrop onion that you can sow directly into your plot. It's a reliable performer, known for excellent storage qualities and firm, golden bulbs. | No club votes yet |
| Cabernet Cabernet is a lovely red maincrop onion, best suited for indoor sowing. It's a reliable performer, giving you attractive, deep red bulbs with good flavor. | No club votes yet |
| Cortland Cortland is a robust maincrop onion, great for direct outdoor sowing. It's a reliable performer, producing firm, globe-shaped bulbs that store really well. | No club votes yet |
| Highlander Highlander is a strong maincrop onion, best started indoors to get it going. It's a reliable performer, known for its vigor and consistent yields of good-sized bulbs. | No club votes yet |
| Ringmaster Ringmaster is a cracking white maincrop onion, perfect for sowing directly outside. It’s a reliable performer, producing crisp, sweet bulbs ideal for fresh eating. | No club votes yet |
| Super Star Super Star is a reliable maincrop onion, a great choice for starting indoors. It produces large, sweet bulbs that are excellent for slicing and fresh use. | No club votes yet |
Votes are members rating varieties in their Seed Tin, one vote per gardener. Tap a variety for the full page and where to buy.
Buy Bulb Onion seeds
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Sowing by USDA zone
| Zone | Sow / plant | Harvest |
|---|---|---|
| Zone 3 | April to May | August to September |
| Zone 4 | April to May | July to September |
| Zone 5 | March to May | July to September |
| Zone 6 | March to April | June to August |
| Zone 7 | February to April | May to August |
| Zone 8 | February to April | May to August |
| Zone 9 | October to March | April to August |
| Zone 10 | October to February | March to August |
Cook the harvest
The definitive French onion soup — deeply caramelised onions slow-cooked in beef broth with wine and thyme, ladled into crocks and topped with toasted baguette and a thick blanket of Gruyère grilled until bubbling and golden. This recipe is unhurried and deliberate; the forty-five minutes of slow caramelisation are entirely non-negotiable and entirely worth it. It is one of the great classic dishes of the home kitchen.
90 min · mediumInspired by the tarte flambée of Alsace, this savory tart fills a crisp, buttery pastry shell with a silky custard of slowly cooked onions, crème fraîche, eggs, and gruyère — a sophisticated balance of sweet onion, rich cream, and nutty cheese. It is elegant enough for a dinner party starter and satisfying enough to anchor a light supper alongside a crisp green salad. Prepared in advance and served at room temperature, it is also an ideal make-ahead dish.
90 min · mediumA buttery, flaky pastry shell filled with a silky custard of slow-caramelized onions, nutty Gruyère, and eggs — essentially a French Alsatian tarte à l'oignon in all its refined simplicity. The onions melt into something sweet and complex during their long cook, the Gruyère brings earthy depth, and the custard sets into a tender, trembling slice. Served warm or at room temperature, this is the kind of tart that turns a simple lunch into an occasion.
100 min · mediumSmall, disc-shaped cipollini onions roasted whole in a sticky, caramelized balsamic glaze until their exteriors are deeply bronzed and their interiors are meltingly soft and sweet. The balsamic reduces in the pan alongside the onions to form a rich, syrupy sauce that coats every onion. They make an elegant side for roast chicken or pork, a stunning addition to grain bowls, or a simple appetizer with a wedge of ricotta and crusty bread.
50 min · easyWatch for, and grow alongside
Companions: carrots, beets, tomatoes, lettuce, brassicas
Questions people ask
When do you sow Bulb Onion in the US?
Sow Bulb Onion from March to April in zone 6, earlier or later by zone. Plant out May, after the last frost.
How long does Bulb Onion take from sowing to harvest?
Roughly 120 days, with the harvest June to August.
Which Bulb Onion varieties do gardeners grow again?
Club members rate every variety they grow. This page shows the grow-again votes for Walla Walla, Candy, Patterson, Redwing and more.
Track your Bulb Onion from packet to plate
Sowing reminders and harvest forecasts for your own frost dates, the Seed Tin, Scan Centre for any label or packet, and the Potty Mouth Garden Club. Free to start.
Allotment keeper in the North East of England, the voice behind the Tony C Smith YouTube channel, and the gardener who built GrowMore CookMore. Club numbers on this page update as members log their plots. Last updated 3 September 2026.