How to Grow Ailsa Craig Onions

Starting Seeds

• 1

  Fill seed trays with seed-starting medium 10 to 12 weeks before the anticipated last frost date. Use a plastic spoon to create drills, or small light indentation lines, along the surface of the seed-starting medium, about three inches apart.

• 2

  Sprinkle Ailsa Craig onion seeds into the drills, and cover them lightly with about one-quarter inch of seed-starting medium. Water the seed trays until the seed-starting medium is moist. Place the trays under grow lights and keep the seed-starting medium moist until the seedlings are about 4 inches tall.

• 3

  Trim the Ailsa Craig onion seedlings with scissors once they reach 4 inches in height. Maintain the seedlings at no taller than 4 inches until the average last frost date. Trimming makes the plants stockier and stronger.

Transplanting and Cultivation

• 4

  Just before your area's average last frost date, prepare the onion bed by incorporating ample quantities of mature compost into the soil with a spading fork. Smooth the bed with a bar rake.

• 5

  Create transplant drills with a Warren hoe, using the pointy arrow-shaped hoe tip to make straight line indentations in the surface of your prepared onion bed to a depth of approximately 1 inch. Place the rows about 18 inches apart.

• 6

  Water the seedling trays well, then use a plastic spoon to lift and gently separate the Ailsa Craig seedlings. Place the root end of each seedling in the prepared drill about six inches apart and cover the roots with soil. Water-in the seedlings with a dilute solution of fish emulsion fertilizer, mixing the fertilizer with water to about half the strength of the manufacturer's directions.

• 7

  Water the onion bed regularly through the growing season if there is not ample rainfall to keep the ground moist. Fertilize with fish emulsion fertilizer, mixed with water to the manufacturer's specifications, every three to four weeks.

Harvest

• 8

  Stop watering and fertilizing the onions when the tops begin to bend over, usually around mid-August. Observe your onion bed until nearly all the tops have bent over.

• 9

  On a dry sunny day, when the weather is predicted to remain free of rain for several days, use a spading fork to gently lift the rows of mature Ailsa Craig onions from the ground. Leave the onions lying for several days on the ground to dry off in the sun.

• 10

  Gather up the harvested onions by hand, brushing off any dirt still clinging to them. Clip off leaves and roots with pruners, and place the onions in mesh bags or baskets.

• 11

  Store the bags or baskets of onions in a cool, dry location. Ailsa Craig onions are sweet and juicy and do not store long, especially in warm temperatures, so plan on using them within six weeks of harvest.