How to Plant Onions in the Ground: Step by Step Guide for Beginners

Introduction: Why planting onions in the ground is worth it

Want to know how to plant onions in the ground? Do it right and you get crisp, storage-ready bulbs that beat store-bought onions on flavor and cost.

Growing onions in the ground gives bigger yields, better drainage, easier weed control, and the freedom to grow varieties like Walla Walla or Red Baron. You save grocery money, stagger harvests with seeds or sets, and store a year of onions.

This guide gives a simple, step-by-step plan: choose site, prep soil, time planting, set spacing and depth, water and feed, then harvest and cure. Expect exact timings, measurements, and quick fixes for bolting, rot, and pests.

Why plant onions in the ground instead of containers

Planting onions in the ground usually gives bigger bulbs and higher yield, because roots have more room and soil stays cooler and moist. For a backyard bed you can expect fuller storage onions than in pots, with less frequent watering once established. Containers shine when space is tight or you want easy pest control, but expect smaller bulbs and daily watering, especially in summer. If you want maximum yield and size, learn how to plant onions in the ground; use containers only for convenience or small harvests.

When to plant onions: timing and climate considerations

If you are asking how to plant onions in the ground, check your USDA zone and last frost date. In zones 3 through 6 set out onion sets or transplants 2 to 4 weeks before last frost; start seed indoors 8 to 10 weeks earlier. In zones 7 and up plant in late winter or fall so onions mature in cool weather. Choose long-day varieties above zone 6, short-day varieties in the south. Sets give quick crops, transplants produce larger bulbs, seeds take longest, cost least. Plant when soil is workable and above 40 F, match day length to your zone.

Choosing onion types: short day, long day, and intermediate

First thing, match day length to your latitude. Short day onions start bulbing at 10 to 12 hours of daylight; they are for warm climates below about 36° north. Think Vidalia or Texas Early Grano, great for sweet, fresh eating. Long day onions need 14 to 16 hours; use them north of roughly 40° north. Examples are Walla Walla and Copra, the latter is a classic storage variety. Between 36° and 40° choose intermediate types like Candy or Red Baron.

If you are learning how to plant onions in the ground, pick a variety labeled for your zone, and decide use first. For storage, choose firm yellow storage varieties, cure fully after harvest. For eating fresh, pick sweet, short-day or intermediate varieties and harvest before full curing.

Preparing your site and soil for onions

Good soil is the secret to success when learning how to plant onions in the ground? Start by picking a sunny spot, with at least six hours of sun and no standing water. Onions need loose, well-drained soil that you can work to 6 to 8 inches deep.

Step by step soil prep:

1. Test the soil, use a home kit or send a sample to your extension service, check pH and nutrients.
2. Broadcast 2 to 4 inches of compost over the bed, then fork it in to 6 to 8 inches; this improves texture for both clay and sandy soils.
3. If drainage is slow, build a raised bed or add gypsum and extra organic matter; test by filling a 12-inch hole with water, it should drain within 24 hours.
4. Aim for pH 6.0 to 7.0; adjust with lime or sulfur according to your soil test, and apply a phosphorus-rich starter fertilizer at planting, following label rates.

Planting methods: sets, transplants, and seeds, plus spacing and depth

If you are wondering how to plant onions in the ground? here are exact steps for each method, plus spacing and timing you can follow.

Sets

• Plant pointy end up, 1 inch deep, 4 inches between plants, 12 inches between rows.
• Timing, early spring as soon as soil can be worked, or late fall in mild climates for overwintering.

Transplants

• Dig a hole deep enough to cover the roots, set so the top of the bulb is level with the soil surface, firm soil around roots.
• Space 4 to 6 inches between plants, 12 inches between rows.
• Plant when seedlings are pencil thick, usually 6 to 8 weeks before last frost.

Seeds

• Sow 1/4 inch deep, thin seedlings to 2 to 3 inches for green onions, or 4 to 6 inches for bulb onions.
• Row spacing 12 to 18 inches so bulbs have room to swell.
• Start indoors 10 to 12 weeks before last frost, or direct seed as soon as soil warms to about 45 degrees F.

Quick tip, water regularly until established and mulch to suppress weeds and retain moisture.

Watering, fertilizing, and mulching for bigger bulbs

Think in seasons, not chores. First 4 to 6 weeks after planting focus on steady moisture and root establishment, give about 1 inch of water per week, more if the weather is hot. From establishment until tops reach 6 to 8 inches, side dress every 3 to 4 weeks with a nitrogen source, for example blood meal or a garden fertilizer, following label rates; this feeds leaf growth that drives bulb size. Once you see bulbs starting to swell, stop nitrogen, keep soil evenly moist and bump water to about 1.25 to 1.5 inches per week during bulb fill. Cut watering back two weeks before harvest to help skins dry and cure.

Mulch matters, apply 2 to 3 inches of straw or shredded leaves right after planting, top up as it breaks down. Mulch reduces weeds, stabilizes soil moisture, and often produces noticeably bigger bulbs when you follow a proper feeding schedule.

Common pests and diseases and how to prevent them

If you are asking how to plant onions in the ground, start with prevention. Main pests are onion maggots and thrips. Signs include yellowing leaves, holes in the bulb neck, or flabby bulbs. Common diseases are downy mildew, neck rot, and white rot. Look for pale patches, fuzzy growth at the base, or soft rot. Prevent with crop rotation, raised beds, well drained soil, and removing bulb debris. Organic controls include row covers for four weeks, neem oil or insecticidal soap for thrips, diatomaceous earth around stems, and beneficial nematodes for maggots. Remove infected plants immediately to stop spread altogether.

Harvesting, curing, and storing onions the right way

Watch the tops, they tell you when to harvest. When most foliage has flopped and begun to yellow, stop watering for 7 to 10 days, then lift bulbs gently with a fork. For curing, brush off excess soil, spread bulbs in a single layer in full sun for two to three days if weather is dry, otherwise move them to a well ventilated, shaded spot for 10 to 14 days until necks are tight and skins papery.

Trim roots and cut tops to about one inch for storage, or braid tops while still pliable if you grew softneck varieties. Store cured onions in mesh bags, crates, or well ventilated boxes at 32 to 40°F and 65 to 70 percent humidity, away from potatoes. Check monthly and remove any soft bulbs to extend shelf life.

Troubleshooting, common problems and quick fixes

If you asked how to plant onions in the ground, try these fixes. Bolting: cut flower stalks immediately, reduce water stress, switch to day-length varieties. Small bulbs: thin to 3 to 4 inches, reduce watering, side-dress with potassium as bulbs swell. Soft necks and neck rot: avoid overhead watering, improve drainage, harvest and cure bulbs in a ventilated spot. Yellowing leaves usually mean nitrogen deficiency or waterlogging, fix soil; if over half the bed is affected accept losses and rotate.

Conclusion and final insights

The core steps for how to plant onions in the ground? Prepare soil, add compost, set sets or seedlings 1 inch deep and 4 inches apart, water weekly, mulch to suppress weeds. For first season success, feed at planting then side dress with nitrogen after four weeks, remove weeds, and harvest when tops flop. Start with a 10-foot row.