Scallion (Green Onion) Plant Profile

Closeup of scallions (green onions)

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

  • Green onions: Regular onions harvested before they form a bulb
  • Spring onions: Regular onions harvested when the bulb is smaller than a quarter
  • Scallions: Varieties that never form a bulb

There is a specific allium species, Allium fistulosum, that's a clump-forming perennial that never grows into a bulb. These plants generally have the best flavor, but growing them as perennials can require a lot of work. So many gardeners opt to grow the perennial varieties as annuals.

Botanical Names Allium fistulosum, Allium cepa
Common Names Scallion, green onion, Welsh onion, spring onion, bunching onion
Plant Type Annual/perennial bulb
Mature Size 1 to 3 feet tall
Sun Exposure Full sun
Soil Type Rich, sandy, medium moisture, well-draining
Soil pH Neutral
Bloom Time Late spring
Flower Color Yellow-white
Hardiness Zones 5 to 9
Native Area Asia
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Watch Now: How to Grow Scallions

How to Grow Scallions

You can start seed 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 seed about a half-inch to an 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 factor 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 they can 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.

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 perennial scallions, 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 cause disease. The soil should be consistently moist but not soggy.

Temperature and Humidity 

Scallions can be grown and harvested year-round in warm climates. Outside of their growing zones, gardeners can treat them as annuals. The 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 Fahrenheit. Plus, 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.

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.

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.

Varieties of Scallions

There are several varieties of scallions to grow, including:

  • '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.