Leeks are a relatively easy vegetable to grow. Unlike onions, leeks don’t produce a bulb or have the strong pungent smell.
Instead, leeks have a stems that grows longer the deeper they are planted in the soil. Because they are much sweeter and milder, than onions, they are also very gentle on the digestive system.
They can be subdivided in a number of ways, but generally they fall into two distinct categories:
Leeks are frost-tolerant and thrive in cool weather. Although they will do alright in partial shade it is best to select a site with full sun. Growing leeks require a minimum of 4-6 hours of direct sunlight daily.
Transplants can be planted outside as soon as 2 - 4 weeks before the average date of the last 32 F (0 C) freeze in the spring in your area but not before soil temperatures are consistently 40° F (4° C) and above
Growing leeks like a well drained soil, they will thrive in traditional garden beds, raised beds, or even in tall containers as long as the soil is fertile, has been well dug over and loosened to a depth of 12 to 15 inches (approx. 30-42 cm).
Any soil that has been amended with lots of good quality compost or animal manure is a real bonus.
leeks generally have a long growing season, ranging from 70 to 120 days, making it best for most situations to start leeks in the garden with good quality transplants.
The most important aspects of caring for Leeks are;
Thinning is not necessary when transplanting as you will transplant good strong plants at the best distance apart.
Transplant the leeks into the ground when they’re about 6-8 inches (15-20cm) tall. Plant them 6 inches (15 cm) apart in a row. Leave 12 inches (30cm) between rows.
Leeks don't cope well with competition from weeds. To ensure the bed stays weed free and producing good strong healthy leeks, it is important to keep the bed well weeded or a good heavy mulch cover over the bed at all times throughout the season.
Inconsistent moisture yields tough stems, so make sure the leeks are well watered and don't allow the bed to dry out.
Leeks like to grow in soil that is med to high in organic matter and well fertilized.
2 weeks before planting spread 5-6 quarts per 100 sq. feet (5.5-6.6 liters per 9.3 square meters) of all purpose organic 5-5-5 fertilizer.
When transplanting seedlings use liquid starter fertilizer. Side-dress your leeks 4 weeks after transplanting with the same rate of fertilizer used initially, and again 4 weeks after that.
To produce the nice white, tender necks, that are sort after for so many delicious recipes, leeks need to be blanched.
This is done by excluding sunlight as they grow. There are a number of different ways to achieve this, some, more labor-intensive than others
1. Creating a narrow trench 6 to 8 inches deep when you first plant out your seedlings.
As they grow, beginning when the stems are 1 inch (25 mm) thick, add soil back so it comes up to the base of the first green leaf.
2. Another way is to pull soil up around the stems, forming a “hill” similar to hoing up potatoes, as they grow.
3. You can also plant leek seedlings by poking holes in the ground with a stick about 6 inches (15 cm) deep. Plant the leek seedling into the holes and water it in.
This will wash soil into the hole to cover the seedling roots. As the leeks grow the holes will naturally fill in producing nicely blanched stems.
4. The easiest way by far is to not bother blanching at all, which will produce leeks with very short but still usable stems.
I usually consider leeks as a root vegetable and follow the rules for root vegetable crop rotation.
Nematodes, Leaf Miners, Grasshoppers, Mites, and Onion Maggots
leaf spot, downy mildew, black mold, and bacterial soft rot.
While the leaves of leek plants are edible they are very tough and fibrous hence are not often used.
You can start pulling leeks from the ground just about anytime the leeks are 1/2 inch in diameter or larger.
You will probably need to use a garden fork to loosen the soil before pulling. For best quality pull leeks as and when you need them.
In colder areas you can extend the harvest season by mulching deeply around plants but be sure to harvest any remaining stems before the ground freezes.
When preparing leeks for storage wash the stems thoroughly to remove all soil particles, especially any that has collected between the leaves.
For short term storage cut off all but a few inches of the green tops and wrap in plastic. They will keep fine in the refrigerator for up to 2 weeks.
For longer term storage leeks can be frozen.