Gardener's Guide to Growing Onions

growing onions

Onions can be grown in several ways, including from seed, seedling, or bulb. You can grow onions indoors, in containers, or in your garden. Choose onion varieties that will grow well in your region. 


Relatively easy

Type of Plant



Full sun, no shade

Soil Type & pH

Loamy soil, neutral pH

Hardiness Zones

3, 4, 5, 6, 7, 8, 9

Buy Supplies

seeds, soil, trellises, pruners, pots.

Quick Tip: Make sure your soil is loose. If your soil is too tight around the plant, the bulbs may not develop properly. 

The vegetable is hardy and one of the easiest to grow. Still, you’ll need plenty of sunlight, proper soil preparation, and frequent fertilization for optimal plant growth. After about 100-175 days, your bulbs will be mature enough to harvest. You can then cure them in sunlight before storing them.


Onions are one of the most versatile vegetables to plant. They don’t require fussy care and they can grow in a wide variety of locations. Since the plants prefer cooler temperatures to grow in, you can plant them in the early spring or fall, depending when your cooler season is.

growing onions

Photo by PublicDomainPictures licensed under CC0

Onions are also one of the easiest vegetables to grow. Their plants are easy to get started, and you can usually get roots from seedlings within a few days after planting. Plus, you can grow onions from discarded onion bottoms, rather than seeds or seedlings, for easy, continuous growth at your home.


There are numerous varieties of onions to choose from to grow in your garden. You’ll want to decide what color and flavor appeals to you the most. Or, if you want a variety, you’ll need to learn what types of onions will give you the widest variety of texture, color, and taste.

You should also consider your region, as different onion varieties will have different sunlight requirements. Short-day onions need between 10-12 hours of sun, day-neutrals need about 12-14 hours, and long-days need about 14-16 hours of sun per day.

The most common types of onions include:

  • Sweet onions. These are the onions you’d use for onion rings, hamburgers, or caramelizing for dishes. Some common types include Vidalia and Walla Walla.
  • Long-storage onions. If you want to get the most storage time from your onions, choose varieties like Copra or Yellow Globe.
  • Mild onions. If you’re opposed to a strong onion flavor, try milder varieties, like Burgundy or Crystal Wax.
  • Strong onions. For the strongest onion flavor, opt for Ebenezer or yellow onion varieties, which tend to have the most pungent flavor when cooked.


Since onions are fairly versatile, there are a few ways you can choose to grow them. If you live in an area with a cool fall and warm spring, you can grow onions well outdoors in your garden. But, warmer or colder areas can benefit from growing onions in containers or indoors, so they won’t be affected by extreme temperatures.

Doing so can also allow you to harvest your onions year-round, especially if you are strategic in staggering your planting times.


If you want to grow your onions in containers or indoors, the most important thing to do is find an area with plenty of sunlight. Onions need full sun to grow adequately, so a sunroom or outdoor porch is the best place to place your containers during the day.

You’ll also need to make sure your containers are well-draining. If onions sit in consistently wet soil, your containers will harbor bacteria and can cause your onion roots and bulbs to rot.

Alternatively, you can begin onion seedlings in containers in your home so you can transfer them to the garden after any threat of frost has passed for your area.


You have a few options when it comes to growing onions. You can grow onions from seed, seedling, or bulb. The one you choose depends on personal preference, but growing from a bulb may be the most foolproof way and requires less steps to get your onion plants started.

According to Rodale’s Organic Life, seedlings are the most susceptible to diseases. However, if they are kept free from disease, they can yield the best bulbs. Bulbs are the easiest to plant and grow, but their harvesting window can be much shorter and they sometimes yield shoots prematurely.

If you’re growing from seeds, push them about about ½-inch deep into the soil. Seedlings should have their roots fully covered by soil. If you plant bulbs, choose ones that are about one inch in diameter or less. Push them about 1-inch to 1 ½-inches into the soil.


Onion seeds don’t require a lot of space between them if you’re starting them indoors. Once they are about 3-inches tall, you can transplant them to the garden, leaving about 6 to 8 inches of space between them. If you are sowing directly into your garden, leave at least 6 to 8 inches from the start.

Onion rows should be spaced about 12 to 18 inches apart to ensure your plants aren’t competing with each other for nutrients and sun.


As with any vegetable you grow, onions need proper soil preparation and maintenance for optimal growth. The type of soil you plant in, and how well you maintain it, can even affect the size and taste of your onion bulbs.

Fortunately, onions can grow in several types of soil. But, there are a few things to remember when preparing your onion soil to ensure you get the best yield from your plants:

  • Organic material. Onions will thrive in a nutrient-rich soil, so adding organic matter can greatly improve your chances for a high yield and healthy plants.
  • Fertilizer. Onions can handle more fertilizer than other vegetables, and using it in your soil before you plant can significantly improve the health of your onion plants.
  • Well-draining and loose. Onions need plenty of drainage, so make sure your soil is loose to allow air flow and water drainage.
  • Weed-free. Weeds will not only make your garden look messy, but they’ll also steal your onion plants’ much-needed nutrients and water.


Although onions are one of the easiest plants to grow, they’ll still need proper car to thrive in your garden. This video by Howdini provides some excellent tips for gardeners to ensure that their onion plants don’t rot once they begin to form bulbs:

It’s important to unearth your onion bulbs during the growing process to prevent them from rotting. Keep enough soil around the bottom of the bulb to cover the roots so your plants can still receive nutrients.

During growth, fertilize every few weeks. A nitrogen-rich fertilizer will help your plants grow bigger bulbs. You won’t need to water much if you get a day or two of rain each week. You can mulch, if desired, to help retain water.

If you notice any onion plants that have bolted, or grow flowers, remove them from the garden, as they’re ready for harvest.


Depending on the variety of onion you choose to plant, you’ll have to wait between 100 and 175 days to harvest your bulbs. An onion plant gives you some warnings to let you know it’s ready for harvest.

According to The National Gardening Association, onions stop growing when their plant leaves begin to lose color and wilt. Wait a few days to allow the bulbs to fully mature, and then you can harvest them.

Gently pull the bulbs from the ground and allow them to cure in the sun for a few hours to a day, depending on how much sunlight you have. Then, cure your onions fully by spreading them out in a warm, dry location, turning them occasionally for even drying. Allow them to cure for two to three weeks.


Now that you know the basics of growing onions, let’s delve into some in-depth information that will help you learn everything you need to know. You can find loads more resources in the right sidebar. Happy planting!

Photo by Colin licensed under CC BY-SA 3.0.