How to Plant & Grow Onions: Complete Guide

Our complete guide to growing Onions at home - Everything you need to know from planting to caring for your onions to harvesting.

Growing onions isn’t as challenging as you think. Onions are a hardy vegetable, and they grow well in cold weather conditions. Adding some onions to your roasted vegetable dish adds a new flavor dimension to the dish, and they taste even better when they’re from your garden.

Onions suit planting directly to your beds, or you can use raised beds for a bountiful crop.

Growing in raised beds increases airflow to the roots, increase your yield. There are plenty of varieties of onions suitable for growing in your garden.

In the southern states, it’s best to plant most onion varieties in the fall. We always recommend that gardeners use onion sets, as these offer the best success rates, and you don’t have to worry about frost killing your onions.

We recommend sets, but it’s possible to grow your onions from seeds as well. Raise some spring onions to add to a fresh garden salad or red Weatherfield’s for roasting. We put together this guide to give you everything you need to know about growing onions this coming season.

Raised Bed
Onions planted in a raised bed

Tips for Planting Onions

We recommend that you plant your onions in the ground as soon as the last frosts fall. Check your local listings for the final frost dates, and then wait two weeks before planting your onions.

Before the winter sets in, you need to prepare your beds for the following growing season. Make sure you till the soil and turn in some compost to the beds. Leave them to rest over the winter, and you’ll have a fertile bed that’s ready for planting in the early springtime.

Two weeks before you plant, turn the soil to loosen the ground. This technique improves the drainage of the soil while allowing for optimal aeration. As soon as you can work the ground, get planting.

Organic Onion Fertilizer

In most cases, you’ll be planting around late March or early April, as long as the temperature doesn’t drop below 20°F. Select a planting site in your garden that gets full sunlight for at least 6 to 10-hours every day. It’s best to select a location that gets shade in the afternoon.

Onions like growing in soil that’s high in nitrogen, and make sure that the earth is loose and loamy. Compacting the soil affects growth, and you’ll end up with under-sized onions. Onion plants require nourishment throughout the growing season to develop healthy harvests.

Onion seeds don’t last long, so you’ll need to plant fresh seeds each year. If you decide to start your seeds indoors early, then we recommend you begin at around 6-weeks before your planting date. Gardeners should think of onions as a leaf crop, instead of a root crop, and follow growing guidelines accordingly.

You can purchase Onion seeds directly from Amazon

As a result, you’ll plant your onion sets 1-inch below the surface of the spoil. For transplants or onion sets, space your plants at least 4 to 5-inches apart and in rows spaced 18-inches apart. We always recommend that gardeners practice crop rotation when growing onions. As mentioned, onions are heavy feeders, and they deplete soil nutrients quickly.

Raised Garden Beds
Raised Garden Beds: The Ultimate Guide for Beginner’s

How to Plant a Sprouted Onion

It might surprise you to learn that you can plant sprouted onions. However, it’s important to note that you won’t get as many onions as you would when you start from seed. Planting sprouted onions produce plenty of tasty green leaf sprouts, and it’s easy to grow and care for the onions in a container garden.

Fill a 5-gallon pot with fresh potting soil. Add some vermiculite and perlite, along with a dose of nitrogen fertilizer. A week later, place the onion in the center of the pot and plant the sprouted onion around 1-inch below the surface of the soil.

Water your onion, and leave the pot in a sunny area of your yard or on the balcony of your apartment. Harvest the green sprouts as they appear, and add them to your recipes. If your onion produces a shoot that turns into a flower, wait for the flower to mature in the spring, and harvest the seeds for next season.

Planting Onion Sprout
Planting Onion Sprout

Tips for Caring for Your Onions

When you’re growing onions, you need to accommodate this vegetable’s need for nutrients throughout the growing season. Onions require the addition of fertilizer to the beds every few weeks to increase bulb size and provide you with the best harvest.

Stop fertilizing your onions as the onions start to push the soil away and form bulbs. It’s important not to cover the bulbs with soil, or push them back under the surface. The bulbs need exposure during the final maturation stage.

Jobe’s Organic Bulb Fertilizer, Best for Onions

If you mulch your garden every few weeks, then you can get away with watering your onions once or twice a week, even in hot weather conditions. The more you water your onions, the sweeter the taste. However, make sure that the soil is draining well, as waterlogged bulbs will end up rotting and attract disease to your crop.

Your onions growing
Your onions growing

Pests and Diseases Affecting Your Onions

There are a few pests and diseases you need to watch out for when growing onions.


These tiny insects are about the size of a pinhead on a sewing needle. It’s tough to identify Thrips with the naked eye. The best way to test for the presence of this pest in your onion garden is with the paper shake method.

Take a sheet of black of dark-colored paper with you to the garden. Shake the tops of the onions onto the paper. If you notice any small tanned-bodies falling onto the paper, then your onions are dealing with a thrip infestation.

Mix up some insecticidal soap, and spray it over your garden. The thrip should die with two to three treatments. Spray the plants three days apart, and complete your paper test the following week to see if there are any survivors you need to get rid of in your onion garden.

Onion Maggots

These pests also present a threat to the success of your onion harvest. Cover the onion crop with a fine-mesh net. Seal the entrance to the garden by placing soil around the edges of the netting.

Onions maggots like to lay eggs at the base of your onion plants. The netting will prevent them from gaining access to your onion crop. Keep the mulch away from around your green shoots, as it might attract insects to the new growth.

Typically, onion maggots are only an issue for gardeners that deal with extended rainy periods during the summer. If you live in a dry region of the United States, you might not encounter this pest.

Tips for Harvesting Your Onions

Make sure that you pull out any onions that start to develop flower stalks. When the flowers start appearing, it means that your onions stop growing.

If you do get flowers shooting from your onions, harvest them immediately, and use them in cooking with in the next few days. These flowered onions will not store well, and you might have to throw them away if you don’t manage to use them in time.

As your onions start to mature, the tops of the green shoots begin to turn yellow. The sprouts will fall over, and at that point, you can bend the stalks at the base to speed the ripening process. A few days before the harvest, loosen the soil around the garden, as this strategy helps to promote drying.

Onion Harvest
The best part, harvesting your onion crop
  • When the tops of the onions eventually turn brown, it’s time to pull them from the ground or container. Harvest your onions ion the following summer before the onset of colder weather in the fall. The fall weather might spoil your onion crop.
  • Clip your onions roots back, and cut the tops to one-inch in length. You can leave the heads on the onions if you’re planning to braid them. Leave your onions to dry and cure on the ground before storing.
  • Make sure you’re careful when handling your onions. Light bruising can cause the onset of rot, which spreads to the other onions in your root cellar. Store your onions at temperatures of between 40 to 50°F.
  • You can store them in a drawer in a root cellar or braids. Your onions prefer a cool and dry place for optimal storage conditions, aiming the root cellar the ideal storage option for your onion crop.

Recommended Onion Varieties

When selecting your onions for your garden, you have the option of choosing two varieties.

Long-day varieties are better for regions of the United States that have cold weather. Short-day types suit warmer areas of the U.S.

Long-day Onion Varieties

  • Yellow Sweet Spanish – round in shape and large, white to yellow.
  • First Edition – high-yields, plenty of intense flavor, and creamy-colored in appearance.
  • Red Wethersfield – Red-skinned with white flesh. This variety stores well.

Short-day Onion Varieties

  • Stuttgarter – Typically sold in onion sets, this variety has early maturation, with a flat shape and yellow color.
  • White Bermuda – White in color, with flat, thick bulbs. These onions have a mild taste.
  • Burgundy – The best table onions, with a sweet-tasting white flesh and red skin.

Hollie is a life-long gardener, having started helping her Dad work on their yard when she was just 5. Since then she has gone on to develop a passion for growing vegetables & fruit in her garden. She has an affinity with nature and loves to share her knowledge gained over a lifetime with readers online. Hollie has written for a number of publications and is now the resident garden blogger here at GardenBeast. Contact her at or follow on twitter

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