Leeks are a member of the Allium family, closely related to garlic and onions. It is thought to have been in cultivation since the 2nd century BC.
For gardens, leeks are a valuable addition because they can be used instead of pungent storage onions. Leeks are slow to mature but are easy to grow, even in heavy soils.
The edible portion of the leek is the stem, composed of a series of overlapping leaf sheaths. The tops of leeks are much better suited for making vegetable stock than for serving raw or cooked.
Like onions, raw leeks have a strong flavor but can be a nice garnish for soups, salads, roasted veggies, meats, and other dishes, when they are very thinly sliced.
Summer leeks are sown indoors and transplanted in early summer to harvest late summer to early fall. Winter leeks have been bred for greater cold hardiness and are left in the ground over season to harvest during the following spring.
Timing: Harvesting fresh leeks from the garden in late fall and winter for hearty soups is a genuine pleasure. Start summer harvest varieties in February/March in plant flats indoors.
For fall harvest and overwintering varieties, start sowing from March to May in a humus-rich nursery bed outside and then transplant.
Optimal soil temperature is 10-25°C (50-75°F). At least 75% of seeds should sprout in 10-16 days.
Sowing: In plant flats, sow seeds 5mm (1/4”) deep and about 1cm (1/2”) apart then transplant once they are 20cm (8”) tall. Space leeks 15-20cm (6-8”) apart, in rows 45cm (18”) apart.
Growing: Leeks have short roots, so they benefit from fertile soil with lots of compost and ¼ - ½ cup of fertilizer worked in beneath each 2m (6’) of row. It is recommended using a dibber (pointed wooden stick) to make holes 15cm (6″) deep.
Transplants are then set at the bottom of the hole and the hole is left unfilled as rain will fill it in as the leek grows.
The goal is to blanch the largest and longest portion of the stem by hilling up the soil around the stem as the leek grows, or mulch with straw.
pH level of 5.5-6.5.
Harvesting: Dig leeks once they are 2cm (1”) in diameter or larger. If winter harvest leeks freeze solid, it is best to wait until they thaw out during a warm weather to later harvest.
Protection: During severe cold climate, when the forecast is below -10°C (14°F), cover the bed with a tarp, or line the row with straw bales topped with rigid plastic or windows.
Pests and Disease: Like most other Alliums, leeks are relatively trouble free – practice diligent crop rotation.
Companion Planting: Grow leeks with beets, celery, onions, spinach, and carrots, as they help repel carrot rust flies. Avoid planting leeks near beans and peas.
Storing: Overwintering leeks are so hardy they are best stored in the ground. Otherwise, keep in a root cellar for several weeks.
Wild leeks are known as ramps and grow wild in the woodlands of eastern North America. Compared to leaks, ramps have a more pungent flavour and are often compared to a combination of onions and strong garlic.
Leeks and wild ramps boat a variety of nutrients that may improve your digestion, promote weight loss, reduce inflammation, and fight heart disease. They may also lower sugar levels and fight infections.
These alliums make great additions to a healthy diet.