Family: Liliaceae
Genus and Species: Allium fistulosum
Climate
Scallions will grow in many climates. The most important factor for growing scallions is the amount of daylight they receive.
Soil
Next to daylight, soil is the key to growing good scallions. Deep, loose, fertile, friable soil works well for growing scallions. Mix in compost or rotted manure to your bed before you plant. Scallions will grow best in soils with a pH of 5.3 to 6.0.
Spacing
Spacing is for convenience sake with scallions. Choose a spacing that suits your needs.
Direct Seeding
Direct seeding scallions provides the least amount of disturbance to the growing cycle. Scallions grown by direct seeding are more resistant to disease. Direct seeded scallions take longer to reach maturity so it is not always the best option in northern climates. Sow scallion seeds in a prepared bed after the soil has warmed to 50°. Sow scallion seeds in rows about 1/4" to 1/2" deep. Thinning is not necessary.
Seeding For Transplants
Scallions can be started indoors on heat mats and underneath growing lights 8-10 weeks before the last frost. Sow 2-5 scallion seeds per cell in a cell tray. Cover seeds with about 1/2" of light potting mix and mist to moisten the mix. Thin seedlings no more than 3 per cell after the first true leaves appear.
Transplanting Into the Garden
Scallions grow best when the early part of their growth cycle is cool. Plant scallions in early spring in cool climates. In mild winter areas, plant scallions in the fall to grow through the winter. Plant scallion starts in a moist, prepared bed. While spacing is not that important, aim for 2"-3" between plugs.
Watering
Scallions do not need to be constantly moist, but their shallow root systems makes them sensitive to drought. Do not let the soil dry out to the level of the scallion roots. Use straw mulch to help retain moisture and keep out weeds.
Harvesting
Scallions are ready when they reach the thickness of a No.2 pencil.
Harvest scallions by gently pulling on the green tops. Use a garden fork to carefully loosen soil around the scallions if needed.
Post-Harvest Handling
Scallions benefit from cooling immediately after harvest. Clean the scallions of dirt and cool using hydro cooling. Hydro cooling is the process of spraying or immersing vegetables in chilled water.
Storage
Scallions should be stored at 32° and 95% to 100% relative humidity. Scallions are quite perishable and are normally marketed or eaten promptly. Scallions can be stored 7-10 days at 32° if moisture loss is prevented.
Diseases
Botrytis Leaf Blight, Purple Blotch, Pink Root, Downy Mildew, Damping Off, White Rot, and Nematodes
Pests
Onion Thrips and Maggots
References
Bradley, F. M. and Ellis, B. W.(Ed.). (1992), Rodale's All-New Encyclopedia of Organic Gardening: The Indispensable Resource for Every Gardener, Emmaus, Pennsylvania: Rodale Press.
Oregon State University, Green Bunching Onions , Commercial Vegetable Production Guides, Last modified 2003-01-06, http://oregonstate.edu/Dept/NWREC/oniongr.html, Accessed 2003-7-14
Smith, E.C. (2000), The vegetable gardener's bible: discover Ed's high yield W-O-R-D system for all North American gardening regions., Storey Books: Pownal, VT.