Leek, an easy vegetable: sowing, care, diseases, pests

Only the part of the stem buried under soil turns white, which is why leek (Allium porrum) is earthed up again and again as it grows. Sown from midwinter to early autumn, it asks little more than steady ridging; do that, and most varieties are hardy enough to harvest all winter, straight from garden to table.

Leek at a glance

Name	Allium porrum
Family	Alliaceae
Type	vegetable
Height	15 to 24 inches (40 to 60 cm)
Exposure	full sun
Soil	light, drained
Lead time	sow 5-7 months before harvest
Harvest	summer, fall, winter

Here is our advice on how to grow leek well, from sowing to harvest – without forgetting the all-important ridging!

Read also:

• Treatment: allium leaf-mining fly
• Health: leek health benefits

Sowing and planting leek

The sowing season for leek extends more or less from Midwinter to early autumn.

Sowing can start relatively early in the season, as long as there is a protected space that is relatively warm (above 60°F, or 15°C) like a greenhouse or an indoor space fitted with heating.

• No need to give each seed an individual nursery pot: at an early stage, sowing in a tray is the most effective way to start.

It is of no use to sow leek in the ground directly until soil temperatures reach at least 54°F (12°C).

1- To harvest leek in spring

To harvest leek in the spring, you must have sown the leek at the end of summer or during fall of the preceding year.

• Sow directly in the ground in late summer or early autumn.
• Thin regularly to give the more vigorous stems the space they need to develop.
• If you prepared your seedlings in nursery pots, transplant in mid-autumn or late autumn at the latest.

2- For a summer leek harvest

To harvest leek early in the season, it is necessary to sow seeds during the winter.

• Sow seeds indoors in midwinter if you live in mild climates, and in late winter or early spring elsewhere.
• Thin as soon as seeds sprout, and again repeatedly as often as needed to ensure that the leek always have space to grow.
• As you thin, you’ll have a steady stream of small but very tasty leek from the beginning of the summer.

3- To have leek to harvest in fall

This is the ideal season to grow leek because temperatures allow for normal, outdoor cultivation.

• Sow the seeds in a nursery or indoors from early spring to late spring.
• Thin as soon as seeds sprout, and again repeatedly, as often as needed to ensure that the leek always have space to grow.
• When the stems of the plants have reached ¼th inch (½ cm) across, transplant them to their growing bed, lightly snipping the tips of their roots and leaves to spur regrowth.
• Space them 4 to 6 inches (10 to 15 cm) apart.
• When transplanting leek to the growing bed, space each plant 4 to 6 inches (10 to 15 cm) apart, and space rows 10 to 12 inches (25 to 30 cm) apart.

Caring for leek

Growing leek is very easy, and here is how to ensure a bountiful harvest and avoid diseases.

Ridging leek

In order to whiten the base of the leek, it is important to ridge leek stems regularly. This is also called blanching. This is an important step in growing leek because only the underground portion will become the white part of the stem.

• Ridging leek means to gather soil up along the base of the stem in order to create a small mound.
• Only the underground portion stays white, so the more they are buried, the longer this portion will be.

Watering leek

Leek plants only need water in case of prolonged dry spells or heat waves. It’s better to avoid over-watering.

• A normal rainfall pattern should perfectly answer the water needs of leek.
• Water only in case of prolonged dry spells or heat waves.
• Nonetheless, feel free to mulch around leek stems to retain rainfall as long as possible.
• Hay, flax or hemp mulch is perfect.

Note that ridges can also help drain excess water away, or retain it, depending on how they run along the slope. Plan your rows depending on whether you need to make sure water runs off easily (top → down ridges) or retain water in dry areas (ridges along a same level line).

>>  Video tutorial on how to grow leek  <<

Diseases and parasites that attack leek

Leek is vulnerable to certain diseases, and preventive treatment is recommended; but best is to space the stems well to avoid fungus altogether.

Run the hoe along the ground to remove weeds and let rainwater seep into the ground easily.

• Blight: yellow and then brown stains appear on leaves
• Powdery mildew: a white velvet-like layer develops on leaves
• Aphids: leaves curl up and shrivel
• Leek leaf-mining fly: there are efficient treatments sold in stores, but it is possible to use fermented stinging nettle tea sprayed regularly as a preventive treatment against the allium leaf-mining fly

Leek companion plants and incompatible plants

Leek responds more or less well to the presence of other vegetables in the patch. Here are the good companion plants followed by the ones leek is incompatible with.

Leek COMPANION vegetables

In the vegetable patch, it is important to match plants correctly to ensure that companion plants are located near each other.

egetables to grow near leek:
Carrot, celery, strawberry, onion, tomato, lettuce, corn salad or asparagus

Plants NOT COMPATIBLE with leek

Certain plants would compete with leek and it is best to plant them apart to avoid them hindering each other.
Bean, silverbeet, cabbage or pea.

Cooking is a very different story altogether, and combining these vegetables together can be very savory.

Vegetables to plant after harvesting leek

For good crop rotation, in order to maintain good levels of nutrients in the soil, here are the vegetables that are suited to planting after leek:

Carrot, cucumber, coriander, squash, bean, turnip, radish or tomato.

Species and varieties of leek

All leek varieties share the same health benefits and therapeutic values.

Some varieties of leek are very interesting:

• ‘Bleu de Solaise’ – hardy, sown late winter to late spring, harvested in winter.
• ‘Gros long d’été’ – rather sensitive to cold weather, it is to be sown in spring or summer for a harvest in summer.
• ‘Carentan leek’ – very good, it is to be sown from late winter to late spring and harvested from summer to winter.
• ‘Elephant leek’ – the thickest of all leek, it is to be sown as early as late winter and harvested in the summer or fall.

You will perhaps find solace in the following varieties as well:

• Common leek or ‘Très long d’hiver de Paris’ – perfect as a winter leek.
• ‘Maxim’ – harvested from summer to fall.
• ‘Carlton F1’ – since it grows quickly, it can be sown directly in the open field.

Most leek varieties are very hardy and will let you harvest this vegetable all winter long, straight from garden to table.

• ‘Long de Mézières’ and ‘Bleu de Solaize’ leek also resist cold very well.

Keeping leek seeds

Let a few of the nicest, most vigorous stalks go to seed. Beautiful flowers will pop up that are white or shades of violet. These dry out with tiny seeds in each capsule at the end.

Label a paper pouch with the date and the variety, and store in a cool, dry place that’s well ventilated.

Note that because of cross-pollination, the variety might not come out true, but unless it’s a hybrid, it will keep many of the mother plant’s characteristics.

Tip: those dry flowers make for excellent dried flower bouquets because they hold for a long time.

Which leek variety to choose

Leek varieties differ mainly in when they are sown, when they can be lifted, and how well they stand the cold. Use the table below to match a variety to the season you want to harvest in.

Most leek varieties are very hardy, so a winter type left in the ground means harvesting straight from garden to table.

Learn more about leek

Its origin stems from the Mediterranean sea, and leek is cultivated today almost all over the world.

Very much savored for its taste and nutritional value, leek is also well recognized for its many health benefits and therapeutic values.

It is replete with vitamins C, E, fibers and pro-vitamin A, and leek helps the digestive tracts function correctly and keeps many illnesses at bay.

Leek is a low-caloric vegetable often recommended for diets, which also helps regulate gastrointestinal functions.

Leek can be eaten both raw and cooked, but most leek-based recipes involve cooking it. Pie or leek quiche are favorites.

 

• Did you know that green leek leaves often are included in bouquet-garni, the bundle of herbs used to prepare meals for fine dining?

Read also about leek:

• Health: leek health benefits and therapeutic properties

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