Growing summer leeks

What are summer leeks?

Leeks are distinguished between summer leeks and winter leeks by their growth period. Early varieties with rapid growth, generally sensitive to cold, these leeks grow from mid-winter to summer, when they are harvested as needed.

Some examples of early varieties among the best:

• the ‘Jaune gros du Poitou’, which offers remarkable taste qualities and is harvested from June to September;
• the ‘Electra’ leek, which produces large boles and is harvested from August to November;
• the ‘Early Giant Major’ leek, a productive variety with very large boles that is harvested from June to July and from September to November.

Sow summer leek

When to Sow?

Summer leeks should be sown very early, that is to say from January to March.

How to Sow?

To germinate, leek seeds require a minimum temperature of 10°C. They are sown on a hot bed to ensure the best growing conditions. This traditional sowing method involves protecting the leek seeds under a frame after sowing them in seed compost, which is placed on a thick layer of fresh organic matter, such as horse manure. The organic materials, as they decompose, generate enough heat to warm the compost.

Frame for sowing on a hot bed.

Preparing the Hot Bed

• Prepare your hot bed from November.
• Define a growing area and cover it with a glazed frame.
• Install a layer of 30 cm of organic materials (horse manure, leaves, herbs, straw, green waste chippings…)
• Cover with 15 cm of seed compost.
• Sowing starts 3 weeks later, once the temperature under the frame has dropped to between 20 and 25°C.

Note: the hot bed can be buried or raised.

The Sowing

• Dig a furrow 1 cm deep in the compost.
• Sow one to two seeds every centimetre.
• Close the furrow and lightly firm it down.
• Gradually ventilate to avoid excess heat under the frame (ideally, summer leeks are sown at 14 to 16°C).
• Germination takes about 20 days.

Sowing leeks © chjmb2000 – Flickr

How to plant summer leeks?

When to Plant?

About two to three months after sowing, proceed with transplanting in place. Your summer leek plants should then reach a height of around fifteen centimetres and have the thickness of a pencil. Depending on the climate, planting occurs between mid-April and mid-May.

Location and Soil Preparation

Leeks prefer to be planted in a sunny location, in soil that is light, cool, deep, loose, well-drained, and rich. The site should be enriched several months in advance, as leeks are sensitive to fresh manure. Also remember to loosen the soil before planting.

“Dressing” the Leeks

“Dressing” the leeks allows for better rooting and limits rapid evaporation.

Young leek plants © G. David

• Gently pull up the young plants from sowing, place them in the shade and let them dry out in the soil for two days. This operation helps to remove the leek’s odour and thus prevents onion fly.
• Afterwards, cut the roots of the leeks 2 to 3 cm below the bulb.
• Trim the young leaves a few centimetres above the bole.

Planting

• Dig holes 15 cm deep, spacing them 20 cm apart in all directions.
• Insert your summer leeks so that their entire white part is buried.
• Water generously with a fine spray (use a watering can with a rose).
• Install fresh lawn between the ranks to add nitrogen to the soil.

Summer Leek Care

Hill up your summer leeks about a month after planting to keep the bole protected from light. This operation helps to keep the leek’s bole nice and white, as well as tender, while also increasing the length of this edible part. To do this, bring the soil from between the ranks to the centre of the planting furrow, around the leeks.

Leeks hilled © Jacques GAIMARD

The summer leek requires no further maintenance, other than occasional weeding and hoeing, as well as regular watering.

Tip: pair your summer leeks with carrots to simultaneously deter both carrot flies and leek flies. The summer leek is also a very good companion for tomatoes, lettuces, and strawberries, protecting them from certain fungal diseases. However, keep it away from onions, as well as beetroot and bean plants.

When to harvest summer leeks?

Early varieties, the harvest of summer leeks generally takes place between June and September, which is between 5 and 8 months after sowing. They are then harvested as needed, gently pulling them to avoid damaging or cutting into their bole. If you encounter difficulty, use a small spade to lever and extract the leek from the soil more easily.

The leek can then be stored easily for 15 days in the vegetable drawer of the refrigerator. They can also be stored for 3 months in the freezer after being blanched for a few minutes, thoroughly dried, and placed in a freezer bag.