Onions come in a wide variety of shapes, sizes, and colors. The white, yellow, or red bulbs range in size from small pickling onions to large Spanish cultivars; they can be globe-, top-, or spindle-shaped. You can start onions from seeds sown indoors in February or early March. The advantage to using seeds is that you have a greater selection of varieties, such as the big, sweet ‘Ailsa Craig’ and ‘Walla Walla’ cultivars. You can grow onions from transplants, sets, or seeds. You can buy transplants, which are seedlings started in the current growing season and sold in bunches, from nurseries or through the mail. Sets are immature bulbs grown the previous year and offer the most limited cultivar choices. They’re the easiest to plant, the earliest to harvest, and the least susceptible to diseases. If you plant onion sets, the sets may be identified only as white, red, or yellow rather than by variety name. Most growers prefer white sets for green onions. When buying sets, look for 1/2-inch-diameter (1,5 cm) bulbs because they’re the least likely to bolt. Growing onions from seed offers the great advantage of a wide choice in cultivars. The challenge with starting from seeds is that your crop will take up to 4 months to mature. Gardeners in cold-winter areas will need to start their onion seedlings indoors. One way to start onions from seed indoors is to sow the seed in two rows, about a quarter-inch (0,6 cm) deep, in 4 x 6-inch (10 x 15 cm) containers filled nearly to the top with a seed starting mix. Keep the containers warm (near, but not too near, the wood stove, for instance, or on top of the refrigerator) and keep the seed starting mix moist. The seeds may take a couple of weeks to germinate; In early May, transplant the seedlings to a fertile, well-drained spot in the garden. As with sets, place four plants in each planting hole, and space each bunch of four onions about 6 inches (15 cm) apart. Once onion tops turn yellow, use the back of a rake to bend them over horizontally. This stops the sap from flowing to the stems and diverts the plant’s energy into maturing the bulb. A day or so later, when the tops turn brown, pull or dig the bulbs on a sunny day, and leave them to dry in the sun. Lay the tops of one row over the bulbs of another to help prevent sunscald. When the outer skins are thoroughly dry, wipe off any soil and remove the tops—unless you intend to braid them. Store in a cool, dry place; hang braided onions or those kept in mesh bags in an airy spot. Such dried bulbs will keep for about 4 months to 1 year.