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Sowing leeks, growing leeks, planting leeks
In our region, you can find leek in every vegetable store. If you want to make a tasty soup you cannot do it without leek.
Around here everyone knows leek as a tasty vegetable and every gardener is growing leeks.
If you want to start growing leeks, just read the rest of this article.
What is a leek?
The Latin name for leek is Allium Porrum. Leek is part of the Alliaceae, it belongs to the genus Allium. One of the family members of the leek is the onion.
Leek has been cultivated for several dozens of centuries. It spread through Europa thanks to the Greek and the Romans.
Leek is a biennial plant, this means, it grows vegetatively the first year and it develops flowers in the second year after going to a cold period in winter.
The first year is important to us, the vegetative phase (where it’ll only grow leaves and no flowers) is the leek that most people know. The second year, leek can only be grown to make seed because the leaves die off when the plant starts flowering.
Most people only use the white part of the leek, this is the beginning of the leaves that is covered through hilling the plant. If you don’t want to hill the plant, you’ll see that the white part is much smaller.
Growing leeks where?
Leeks need a nutrient-rich, airy and moist soil (not wet).
In somewhat heavier soil it’s fairly easy to grow leeks but you still have to bear in mind that heavy soil can easily collapse (stick together and get devoid of oxygen) which will, in turn, make your plants vulnerable to some nasty diseases.
Also, in hard soil, it’s difficult to harvest leeks, especially in the professional cultivation. The leeks will be more difficult to clean up than for instance in sandy soil (but that’s only a minor problem). On the other hand, sandy soil dries out really quickly which is damaging to the leek plants.
It’s best to sprout the seeds at temperatures of about 18°C ( 64,4°F). With lower temperatures, it’s very much possible that the leeks will all of a sudden start flowering(which makes the plant useless for consumption).
A leek needs a PH of 6 to 7, lower ph or higher ph will result in stunted growth and a higher risk of getting diseases.
If you want big, healthy plants, it’s good to have a lot of humus in the soil. Still, it’s better to work in the compost or manure a couple of weeks before you start growing leeks if you want to avoid the leek fly.
Make sure the soil is loose and airy down to 30 cm deep (one foot) to make sure the roots can penetrate the soil deep enough.
As with most vegetables, it’s good to use crop rotation and wait at least 4 years before replanting a plant that is part of the same family in the same place.
Taking care of your leeks and how to grow leek
As mentioned above, leeks do like their nutrients. Amending the soil with compost or manure in the winter time will give you good chances of growing big, healthy leeks.
I personally amend with organic fertilizer after about 2 months and once again 2 months later just to make sure the plants get enough nutrients.
Refertilizing after 2 and 4 months is best done with an organic fertilizer but no fresh compost or manure, once again to avoid the leek fly.
Leeks will get yellowish leaves and a stunted growth when there’s not enough nitrogen in the soil.
If there’s a shortage of phosphor, the leaves will lose their shine and you could even see the leaves turning color towards blue and purple.
If the tips and sides of the leaves start to die off it’s very much possible that the acidity level isn’t right for the plants, you can partially help the plant in this situation by adding seaweed calcium but it’s always better to test the soil before planting anything.
When there’s not enough potassium in the soil the tips can start to curl down. But watch out with potassium, too much potassium with too much moisture can lead to a deficiency in magnesium.
When to grow leeks
If you want a summer crop, you can sow in small pots or small bins in the month of January. Of course, it’s necessary to keep the plants indoors until the last frost.
I don’t do any leek cultivation in the autumn, but if you want to you can do just the same as the summer crop but with a different kind of leek and a couple of months later.
Up until half of June, it’s still possible to sow for a winter crop, best to do it in a bin but outside (not in a hoop house, greenhouse or cold frame).
Leek seeds can take up from 10 to 25 days until germination, so the start can be spread over a period of 2 weeks (lots depends on the temperature).
I always use a small shovel to lift up the root system while I pull out the plant. There’s nothing special about harvesting leek plants.
update: I now cut off the leeks at soil level when I harvest them. This doesn’t harm the plant as it is being harvested anyway, and it gives the soil more fibrous material which will improve the soil in the end.
The small yellow worms (larvae) belonging to the leek moth can mine the leaves towards the center of the plant. In the end, they will kill the plant. Acting in a timely fashion is very necessary. To treat this problem biologically, you can use a product containing bacterium thuringiensis. Just make sure to read the instructions on how to use the product, when to use the product and how much of the product you need because more isn’t always better.
The larvae of the leek fly can cause disaster in your plants. The larvae enter the plant on the bottom side and eat their way up in the plant.
Making sure the plant has enough moist will decrease chances of contamination but isn’t a certainty.
In worse case scenario you could turn to a product containing spinosad, which is permitted in organic farming in Belgium to treat the plants. But the damage can already be fatal when you see the symptoms. Be careful though because spinosad kills lots of insects, for instance, bees and bumble bees so be really careful if there are blooming plants around your leeks.
Leek rust is a fungal disease. Puccinia allii or rust has a tendency to show up if the soil and the air are too moist (too much rain in the fall or springtime) when growing leeks.
Luckily for the winter crop, the rust will die off as soon as the first frost comes by.
Fusarium, also a fungal disease tends to grow during wet periods. It’s possible to recognize fusarium when removing the plants (and you’ll see when you have to remove it, don’t worry). The bottom of the plants and the roots will have started rotting.
You can treat the plants. You can put them in a specific liquid before you plant them out. (that isn’t too organic). Maybe a good precaution would be not to crush the roots while transplanting the leeks. Also, make sure the plants have all the nutrition they need to grow and not get stunted.
Once again, crop rotation is really important here. Fusarium can build up in the soil when replanting members of the same family on the same spot.
Paper spot disease
Phytophthora porri or paper spot disease (once again a fungal disease) on leeks shows itself with dried out spots on the leaf. These spots tend to get so fragile that the leaf itself breaks over to the outside.
Once again, too much moisture is the damaging reason. Kind of special is the fact that it has something to do with the rain splashing on the ground and bouncing back up to the leaves. It’s not only the moist but more the rain that gives this disease a chance to grow.
As soon as I get pictures with a certain disease on, I’ll put them in this article. It’ll be a bit more easy to see what could be happening to your plants. For now, I have to rely on Wikipedia to show you some pictures. Anyhow, if you do have a disease you don’t really know anything about, just send me a message with pictures. I’ll respond as soon as possible.
So this is it for this article on growing leeks, I hope you’ve found it interesting. If so, please share on social media, with friends, and other gardeners.
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Thanks for reading and see you in the next post.