How to grow green onions: The ultimate seed to harvest guide

Green onions are one of the most widely used vegetables in the kitchen, but did you know they’re also quick and easy to grow? And that there are several types of onions you can plant to produce green onions? This vegetable is grown for its tender stalks and leaves that have a mildly sweet onion flavor. I love them so much I keep a steady supply of green onions in my garden year-round! Keep reading to learn how to grow green onions in garden beds or containers. 

What are green onions

The terms ‘green onion’ and ‘scallion’ are often used interchangeably, sometimes with ‘bunching onion’ and ‘spring onion’ tossed in there as well. This crop isn’t grown for its bulbs, but its flavorful greens and tender stems. There are two types of onions grown as green onions:

• Bulb onions (Allium cepa) – Bulb onions are typically grown for their yellow, red, or white bulbs, but they can also be planted to produce green onions. For this, you’ll need to harvest the stalks and leaves while the plants are immature and before the bulbs form. If you wait too long to harvest the leaves from bulbing onions, they can become tough and less palatable.
• Scallions or bunching onions (Allium fistulosum) – These are the preferred type of green onion planted by gardeners and may be grown as annual or perennial plants. For traditional green onions the plants are harvested as an annual vegetable about two months after seeding. They don’t produce bulbs, but if left in the garden to winter over, they form a clump of spiky hollow leaves that persist for many years and flower in summer. Scallions are hardy perennial plants in zones 5 to 9.

Where to plant green onions

Like most vegetables, green onions thrive in full sun so look for a site with at least 6 to 8 hours of direct light each day. The soil should be fertile and well-draining. Raised beds are ideal for growing green onions. Once I’ve chosen the site, I remove any weeds and add an inch of compost to the bed. If your soil isn’t particularly fertile, you can also incorporate a slow release organic vegetable fertilizer before planting for a steady supply of nutrients.

When to plant green onions

My first sowing of green onion seeds takes place in late winter inside a cold frame or my polytunnel. In my main garden I start to plant in early to mid-spring and I follow this up with a mid-summer sowing to provide us with flavorful green onions for autumn harvesting. Gardeners in zone 5 and up can enjoy green onions throughout winter if the cold hardy plants are seeded in a season extender like a cold frame. If you don’t have a season extender you can mulch the plants in late autumn with straw or shredded leaves to extend the harvest into winter.

How to plant green onions

Direct sow green onions or start scallion seeds indoors, transplanting the seedings into garden beds. To direct seed, sow the small seeds 1/4 inch apart in 3 inch wide bands or in a grid pattern, planting the seeds 1/4 inch deep. Once they’ve sprouted, thin plants to an inch apart, eating the thinnings. For larger plants, continue to thin and eat every second seedling as they grow which opens up space for the remaining plants to size up.

If you wish to get a jump start on the harvest, start the seeds indoors 8 to 10 weeks before last expected spring frost. I start them in cell packs and trays, sowing a pinch of about 6 to 8 seeds per cell. Harden off and transplant the seedings into the garden 2 to 3 weeks before the last frost date. Just pop the entire cell of soil and seedlings out of the tray and transplant the clump. They’ll grow in tidy bunches. Space each clump 6 inches apart.

Alternatively if you wish for large thick green onion plants, try the deep planting technique. When transplanting the seedlings, use your garden trowel to make a hole or crevice deep enough that about half of the seedling is buried. Don’t pack the soil back around the plant, but instead water after planting to let the soil settle in naturally. Space transplanted seedlings 6 inches apart.

How to grow green onions

Green onion plants have shallow root systems and dry out quickly so maintain a lightly moist soil. Check soil twice a week, particularly when the weather is hot and dry. Water deeply when necessary. Mulching around the plants with straw reduces the need to water and limits weed growth. Slender green onion plants don’t compete well with weeds, so if you don’t mulch the bed pull weeds as they appear. You may wish to run soaker hoses beneath the mulch to make irrigation quick and easy.

To create longer stalks, hill up the soil around the plants several times during the growing season with a garden hoe. You don’t need to do this if you used the deep planting technique detailed above.

When and how to harvest the crop

If you’re just learning how to grow green onions, you’ll be happy to learn that a patch of plants offers a long harvest season. There are multiple ways to harvest green onions and here are the three techniques I use:

1. I first start to harvest the plants as a baby crop when they’re just 8 to 10 inches tall and at this stage they have a mild, sweet onion flavor. When pulling immature plants, use it as an opportunity to thin between them so the rest of the green onions can size up.
2. If you only need a small amount for the kitchen you can clip a few leaves from the plants which will continue to grow for future harvests.
3. If you want the entire plant – stalk and leaves –  use a garden fork or trowel to loosen it from the soil. Don’t try and tug it from the earth as this can bruise, damage, or break the stem.

We use our green onion crop for salads, soups, stir-fries, baked potatoes, scrambled eggs, and a million other favorite recipes.

How to grow green onions in a container

Green onions grow well in plastic pots or fabric planters on sunny decks and balconies. Begin with smart pot selection. Find a container that offers good drainage and is at least 6 inches deep. Fill it with high quality potting mix and compost. A ratio of 2 parts potting mix to 1 part compost is perfect. Moisten the growing medium and sow seeds, spacing them 1/4 inch apart and 1/4 inch deep, or set your transplants 1 to 2 inches apart. If you want large sized plants, set them 6 inches apart.

Monitor soil moisture during summer, watering often and deeply to keep the soil lightly moist. Use a liquid organic vegetable fertilizer every two to three weeks to promote healthy growth. Harvest anytime the plants are large enough to use.

Pest and diseases to watch for

While green onions are a low maintenance crop, there are a few issues that can pop up. In my garden the biggest pest is slugs and I handpick any that I find. If they’re particularly tenacious I’ll also use diatomaceous earth around the green onion patch. Other common pests to watch for are cutworms and onion maggots. Potential disease issues include botrytis leaf blight, purple blotch, and downy mildew. Practice crop rotation and maintain good spacing to promote air circulation between plants.

The best varieties to grow

There are many varieties of green onions available through seed catalogs. Most have white stalks and green leaves, but there are a few, like Red Beard, that offer bright reddish-purple stalks. Below are five varieties I like to grow in my raised bed vegetable garden.

• Evergreen Hardy White (65 days) – This has been my standard green onion for spring, autumn, summer, and winter harvesting for many years. Evergreen Hardy White is quick to grow and very cold hardy, ideal for cold frame or greenhouse growing.
• Red Beard (55 days) – Red Beard is a unique and colorful variety with bold purple-red stalks. It’s early to mature and makes a delicious green onion in cooked and raw dishes.
• Nabechan (60 days) – This popular Japanese variety forms strong, upright plants with thick stalks and has a sweet onion flavor.
• Parade (65 days) – Parade is a widely available green onion with uniform, upright plants. They have long white stalks topped with dark green leaves. A high quality variety.
• Ishikura (55 days) – Ishikura plants are big! They produce tender 15 inch long stalks topped by 12 inches of bright green leaves. It’s necessary to plant the seedlings deeply or hill up the soil around the plants for extra-long stalks.

For further reading on growing onions, be sure to check out these articles:

• Perennial onions: 6 types to grow
• Why planting onion seeds is better than sets
• Curing onions for long term storage and winter use
• How to harvest chives from the garden
• How to grow green onions from scraps and 10 other veggies to grow indoors

Now that you know how to grow green onions, are you planning on seeding this popular vegetable in your garden?