I’m currently in the process of hardening off the first round of onion and leek seedlings in preparation for permanently planting them outside. To recap, here’s the planting calendar that I follow:
Start Seeds: Since I want the seedlings to have about 8+ weeks of growth before putting them out, I count backwards from the Planting Out date (below) to determine when I need to start them. This is usually early February or March in my region.
Planting Out: I try to get onion seedlings outside around or on the last frost (May 9 in Toronto). My ideal is 3-4 weeks before the last frost, but I don’t fret if I am late. In fact, I often do multiple rounds. I still have some underneath lights that will be going out after this first group.
Hardening Off: I try to give all seedlings about 2 weeks hardening off time. I find out I don’t have to be too delicate with onions, but like all seedlings, they stay healthiest when they’ve been given ample time to adjust, especially if they were grown underneath lights in a warm room and are going out before the last frost. My kitchen is a particularly cool room (except when baking), so I tend to keep them here while they go back and forth from indoors to out through the hardening off process.
Trimming Leggy Onions and Leeks
Even under the very best growing conditions I find that many varieties of onions and leeks produce leggy growth in the 2 months that they are indoors. I trim them back intermittently to encourage strong growth and to prevent the plants from becoming a tangled mess. To do this, simply cut the green part with a pair of sharp scissors, trimming back to about 3-5 inches. Do the last trim before you begin the hardening off process.
Nothing Goes to Waste
Don’t throw the trimmings away! Eat the young, tender greens fresh on top of salads, eggs, potatoes, and meat, toss into meals in the final minute or so, or add to savoury baked goods such as cheese and herb scones. You can also mix them into creamed cheese or dips.