Scallion Plant Profile

Closeup of scallions (green onions)

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Scallions (Allium fistulosum) bring the flavor of onions without the long wait in the garden or the peeling in the kitchen. Although the terms scallions, green onions, and spring onions are often used interchangeably to mean any onion harvested before the bulb fully forms, they are actually distinguished from one another as follows:

  • Green onions: Regular onions (Allium cepa) harvested when they have very small bulbs; leaves are good for eating.
  • Spring onions: Allium cepa onions harvested when the bulb is smaller than a quarter; leaves are edible but not good for eating.
  • Scallions: Clump-forming onions with very thin bulbs; leaves and bulbs are good for eating and are often more tender and mild than those of green onions.

Scallions are perennials that form long, dark green, tubular leaves that change to white bulbs underground, despite being considered "bulbless" onions. The leaves can reach up to 3 feet in height but are typically harvested when they're about 12 inches tall or shorter. Both the stalk and the bulb are prized for their bright yet mild onion flavor and are usually eaten raw. Scallions offer a rapid growth rate and are ready to harvest in 60 to 80 days after sowing. They are best planted in spring for a summer harvest. In climates where scallions grow well as perennials, they can be harvested annually without replanting.

Botanical Name Allium fistulosum
Common Name Scallion, Welsh onion, bunching onion, Japanese bunching onion, Japanese leek
Plant Type Perennial bulb
Size 1 to 3 feet tall and 1 to 2 feet wide
Sun Exposure Full sun
Soil Type Sandy, well-drained
Soil pH Acidic to Neutral (6.2 to 6.8)
Hardiness Zones 69
Native Area Asia
Toxicity Non-toxic

How to Plant Scallions

You can start seeds indoors about five to six weeks before your projected last frost date, or direct sow in the garden once the threat of frost has passed. Sow the seeds about 1/2 to 1 inch deep and somewhat thickly (roughly four to eight seeds in each spot). As with other onions, germination can be slow and poor. The most important element scallion seeds need is constant moisture, which makes starting them indoors where you can keep an eye on them a good choice.

Once you have growth, thin the seedlings to about a foot apart. In addition, make sure you promptly pull any weeds that surround your seedlings, as weeds compete for water and nutrients. For a continual harvest, succession-plant new crops every three to four weeks. This succession planting also will help to reduce any competition from weeds in the area.

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Scallion Care

Light

These are leafy vegetables that can handle partial shade. But they do best and remain healthiest in full sun, meaning at least six hours of direct sunlight on most days.

Soil

Scallions tend to prefer rich, loamy, or sandy, well-draining soil. If you are growing scallions as perennials, apply a thick layer of mulch in the late fall and remove it in the spring when the soil has warmed. You will get an earlier crop this way.

Water

Scallions have a shallow root system, so regular watering and/or rainfall is a must as soon as the soil starts to dry out. However, do not let them sit in wet soil, which can lead to disease. The soil should be consistently moist but not soggy.

Temperature and Humidity 

Scallion seeds generally need a soil temperature of at least 35 degrees Fahrenheit to germinate, though 45 degrees and above is better. The plants like temperatures between 68 and 78 degrees. They do not mind humid conditions as long as they have good drainage to prevent rot and other diseases.

Fertilizer

Give your plants some fertilizer monthly. Fertilizer that is high in nitrogen, such as fish emulsion, will keep them green and growing.

Scallion Varieties

  • 'Guardsman' (Allium fistulosum 'Guardsman'): This variety is ready for harvesting within 60 days of planting.
  • 'Nabechan' (Allium fistulosum 'Nabechan'): This is a Japanese variety prized for its flavor.
  • 'Red Beard' (Allium fistulosum 'Red Beard'): This one features purple-red stalks and is quick and easy to grow.
  • 'Tokyo Long White' (Allium fistulosum 'Tokyo Long White'): This is another flavorful perennial variety with long, slender stalks.

Harvesting

Scallions are tender and mild when they are young. You can start harvesting as soon as the plants reach about 5 to 6 inches tall and are as wide as a pencil. Harvest the whole plant simply by pulling it out of the soil. If you are growing perennial varieties, it is recommended that you avoid harvesting during the first season. This allows the plant to become established and produce a more bountiful crop. Then, trim off the leaves as needed.

Common Pests and Diseases

Most scallions are virtually free of pests and diseases. But one garden pest your scallions might face is the allium leaf miner. This pest lays its eggs on the leaves of ornamental and edible plants of the onion family. The larvae eat their way to the bulb, destroying the plant in the process. If you start noticing problems, planting your next crop in a different area of the garden can help.