I’ve never grown Leeks before. That makes it a bit intimidating but also means I’m spending a lot of time researching them. What do they need? How do they grow? How should I start them?
There are a few varieties of leeks that require different growing seasons. Early season leeks are less hardy and will be ready in time for autumn whereas late-season leeks, depending on your climate, can be harvested through winter and into spring.
The seeds should be started in pots or trays, about an inch apart, and lightly covered with a thin layer of soil. As they get larger, they may need to be separated into individual pots. With how my nursery is set up to work, I will have to re-pot them.
Germination time ranges from 14 to 21 days. For my area, it is recommended that seeds be started February to March and be planted out in May.
Leeks are ready to transplant when they are six to eight inches tall. Holes should be dug that are roughly the same height as the stem of the seedlings and should be about 6 inches apart.
After placing the seedlings, it is recommended that the holes are filled with water but not covered back in with soil. This will allow the stems to swell and help blanch them.
Leeks require rich, loose soil with lots of sun and water. One suggestion is to grow them in between quick-growing salad leaves. By the time the Leeks need that space to grow, the salad leaves will all be harvested.
For companioning planting, is recommended that Leeks are planted near tomatoes, basil, strawberries, cabbage, beets, lettuce, and carrots. Plants to avoid are beans and peas.
Leeks can be harvested whenever they reach a usable size, usually 1 inch in diameter or larger. At full maturity, they may reach 2 inches in diameter. In cold areas, such as Michigan, it is recommended that the leeks are dug up before the ground freezes.
Leeks are biennial so any plants left in the garden will develop flowers and seed heads in the spring, which will change the flavor and become undesirable to eat.
The extension office for my area warns against Onion Thrips, Onion Maggot, Bulb Mite, Basal rot, white rot, downy mildew, and botrytis rot.