Onions

Onions are shallow root plants and need beds that are weed-free and well drained, but also provide constant moisture. Raised beds work particularly well and mulching will keep the weeds at bay and the moisture levels consistent. Onions are also a good choice for intercropping due to their narrow upright habit.

Rotate onions on a three-year cycle to prevent insect and disease build up. Direct seed for scallions or short season varieties, however, to have time for onion bulbs to form start transplants indoors about 8 to 10 weeks before the last frost. Use 4 to 5 seeds per cell or sow in flats in rows ½ inch (1 cm) apart and ¼ inch (5 mm) deep. Trim droopy foliage to 3 inches (8 cm). Harden off and transplant 2 to 4 weeks before last frost. If you plan on harvesting as scallions then space 1 inch (2.5 cm), 2 inches (5 cm) for small bulbs and 4 inches (10 cm) for large onion bulbs. Seed can be directly sown once soil warms to 50F (10C). Plant seeds with the same spacing as seed sown in flats in rows 12 to 18 inches (30 to 45 cm) apart. Thin eventually the same as transplanted starts depending on planned harvest size. Onions can also be started from sets which are small bulbs (no larger than ¾ inch, 2 cm in diameter) stored from the season before. Don't use larger bulbs as they are more likely to bolt. Plant the bulbs an inch (2.5 cm) deep, 2 to 4 weeks before the last frost. Space 2 or 4 inches (5 to 10 cm) depending on what size bulb you wish to harvest.