Table onions (also known as scallions, green onions, or spring onions) grow well from sets in many climates. Sets are small onion bulbs. Since onions tolerate light frost fairly well, you can plant them in your garden as soon as the soil has thawed enough to work in the spring. Spacing is also relatively unimportant, since you will be harvesting your table onions before crowding can become an issue.
Turn over your garden soil as soon as it has thawed enough to work in the spring. Dig down to a depth of about 8 to 12 inches. Add compost in a ratio of 1-to-1 with the soil and mix it thoroughly.
Dig small holes with the trowel, about 1 1/2 to 2 inches deep and about 1 inch apart.
Sort your onion sets by size. Onion sets smaller than a dime should be set aside, as these can be grown into larger onions. Onion sets larger than a dime are the ones you will use, as larger onion sets will often just form a seed stalk after planting rather than form a bulb, according to Texas A&M University Extension.
Plant an onion bulb in each hole, pointy side up. Cover over with soil and pat it down lightly.
Water your table onions regularly, but do not overwater. If you notice the water starting to pool or having a hard time being absorbed, stop watering. You should see onion shoots within a couple of weeks after planting.
Harvest table onions anytime after the tops have grown more than 6 inches, according to University of Illinois Extension. Larger table onions will have more intense flavor. Harvest fresh just before you want to use them for best taste. All parts except the roots are edible.