It’s hard to find a better crop to grow in the vegetable garden, leeks are ready for harvesting deep in the winter, the seeds are cheap, plants require almost no maintenance and suffer from essentially no diseases.
In this article I’ll teach you the secrets to growing leeks from seed and how to get really long “show quality” white shanks.
Sowing Leeks From Seed
Leeks are best sown indoors in the middle of March or outdoors from the first week in April. Sprinkle approximately 15-20 seeds in a 6 inch pot of multipurpose compost and cover with a very fine layer of compost. This is by the best method as the compost really gives the seedlings a very good start.
Alternatively the seeds can be sown into a seed bed for later transplanting or small seedlings can be purchased from most good garden centres.
Once sown leeks can seem to take quite a while to germinate. In ideal temperatures leeks seeds will germinate in 10-14 days but when in cooler conditions this can be closer to three weeks. If the seeds haven’t germinated after 3 weeks it really is time to consider resowing.
If the plants germinate to thickly they should be thinned out early to avoid any root disturbance.
Initially the leeks will look small and thin like tiny onion seedlings. At this stage the plants do often seem to slow down growing, a few weeks after gemination using a good liquid feed will give a burst of green growth which will ensure the plants are really in the best condition before they are transplanted into the garden.
Once the seedlings have grown to be about the size of a pencil they are ready to be transplanted.
Transplanting Leek Plants Outside
Leeks are part of the onion family and as such will need a good soil to grow well. Free draining soil is essential as the winter months can cause rot problems. Adding a good layer of well rotted manure to the final bed in autumn will give the very best results.
Leeks are really tough and shouldn’t need hardening off if planted straight outdoors unless extreme weather is expected.
The method for planting leeks is quite a unique one.
Plants should be spaced about 6 inches (15cm) apart in rows 12 inches (30cm) apart - planting futher apart in very bad soils. These spacings will give quite large leeks that are still ideal for the kitchen however if you are growing for the local show double the planting distances.
To plant you will be using quite a unique method. Use the handle of a sweeping brush and make a mark 6 inches (15cm) up the handle. A brush handle is the perfect tool to use as a dibber for planting leeks. At each planting location push the end of the handle into the soil until it reaches the 6 inch depth mark, drop a seedling in the hole and water well.
Do not fill in the hole with soil, watering will fill the hole a little and over time the soil will fill the lose with lose soil. This hole and lose soil will allow the shank of the leek to grow over the coming months. Some people recommend cutting the roots of the leeks before planting and trimming the tops, research has shown this makes no positive difference to the growth.
Aftercare & Harvesting Leeks
Weeding the plants soon after planting will prevent any weeds having a chance of seriously competing against the leeks and save a lot of work later in the season. Once established the plants should make a canopy that will prevent most week growth.
Blanching is the only extra step needed to get really good leeks. You can successfully grow leeks without this but to get really long shanks you can blanch them. There are two ways to do this:
- As the leeks grow earth the soil up around the stem, this will block out most of the light and can be used to create a good stem.
- In June or July the plants should get to 10 inches (25cm) tall and a 8 inch (20cm) length of plastic guttering downpipe can be placed over the leek to block out sunlight. This is how professional show growers get incredibly long shanks.
Once this step is completed it’s time to just leave the plants to grow until they are ready for harvesting.
Harvesting begins as soon as the leeks are big enough for cooking. In the summer and early autumn small leeks can be picked and used in the kitchen. The main crop should begin in October with harvesting continuing right the way through to early April. Pick the leeks and use them within a week as they do not store for long periods once out of the ground.