How to Grow Cambray Onions

Determine which zone you live in before you begin. Cambrays flourish in Zones 3 to 10, meaning the growing range that covers most of Central and North America. Consult the U.S. Department of Agriculture’s zone chart to determine your zone, if need be. Once you’ve determined your zone, select an area in your garden where the growing onion plants will receive full sun for several hours daily.

Check the pH levels of the soil where you’ll be planting the onions. Cambrays need an acidity level of 6.0 to 7.0, so use a pH soil tester to determine the level. If the soil is deficient in nitrogen, add a soil mix rich in nutrients to bring up the pH. If you’re beginning your onions from seed, prep the seed trays about 10 weeks out from the frost-free date for your area, and plant the seeds about an inch deep.

Prep the soil well in the springtime, and plant the seedlings or transplanted semi-mature onion plants about 2 to 3 inches apart. This equates to about six plants per square foot. If you crowd them, the plants will compete for nutrients and will be much smaller than you would like.

Add fertilizer to the plants or seedlings that conforms to the recommended 16-16-8 ratio. As the plants begin to reach maturity, use only a basic 21-0-0 fertilizer. Water the growing plants well during their 184 day growth cycle. A good way to determine a medium level of water intake is to touch the soil around the plants. If it’s dry to the touch, add enough water until the topsoil feels like a damp sponge. If there’s rain in the forecast, don’t water that day, as oversaturation will lead to root-rot.