When to Plant Onion Sets?

(Question)

I have a garden at the Leslie Street Allotment Gardens in Toronto. It has raised beds. Can you advise when is the earliest I could plant “onion sets”?
Each year I start looking to buy the sets in late March and often can’t find them until end of April but this year, they are already in the stores and it’s April 1st.
I’m eager for fresh green onions but of course, want my onions to be successful. Is it too early now?

 

(Answer)

Thank you for contacting Toronto Master Gardeners with your question about planting onion sets, Allium cepa.

Plant the sets as soon as the ground can be worked in the spring, usually late March or April. Plant them 4 cm deep with 16 to 20 cm between each plant and in rows 30 to 50 cm apart. If frost is forecast when your plants are 6 to 10 weeks old, cover them with a row cover.

The sets grow well in raised beds, in full sun and well-drained loose soil rich in nitrogen. As heavy feeders they will appreciate a side dressing of compost every few weeks until the bulbing process begins. Do practice crop rotation with onions.

Harvest your onions when the tops start to decline, air-dry them for a few days and store them in a dry, cool, well-ventilated area.

We wish you an abundant and tasty harvest.