Leeks don’t often get a lot of love but we’re hoping to change that. This vegetable, which is part of the allium family, is perfect for both stir-fries and as its own side dish. Learn when to plant leeks and how to grow them in your garden.
When to plant leeks: Leeks are a hardy vegetable that can withstand some frosty weather. Plant your leeks indoors in February as they take a long time to germinate. Once the threat of frost is over, usually between April and May, you can then plant your leeks outdoors. Leeks can take between 90 and 130 days to be ready so be patient. Once their stems are an inch wide, you can start to harvest them. If you live in an area with cold winters, harvest any remaining leeks before the ground starts to freeze.
Planting Leeks in Different Climates
Leeks need cool weather to start growing and while they can withstand some warmer temperatures in the summer, a tropical climate won’t be able to sustain them.
Leeks need soil that is moist but well-draining. A dry climate is probably not the best choice.
Leeks will do very well in a temperate climate. In fact, if you live in more mild areas, you might be able to leave your leeks in the ground during winter.
You can grow leeks in a continental climate but you may have to alter your methods slightly. Always start the seeds indoors as the last spring frost date will be later. Furthermore, you will need to harvest your leeks earlier in fall as the ground can start to freeze as early as October.
Leeks need sunshine and warmth so a polar climate is not the best for them.
Choosing Leek Seeds
Those that are tired of the long growing season will appreciate this variety as it is ready in just under 100 days. The stems are nice and thick and the whole vegetable has a mild flavor.
You will have to be patient with this variety as it can take up to 130 days to be ready for harvest. However, the stems can grow up to 30 inches tall, so you get plenty of use out of the variety.
This heirloom variety has a nice, sweet flavor. Its stems are narrow but tall and if you want to try to overwinter your leeks, this is a solid choice.
How to Plant Leek Seeds
Leeks are very hardy and are a perfect backyard crop if you have cooler weather. It is best to plant them in early spring. Their texture allows the plant to withstand storms, hail, and even frost.
You have two options for planting leeks. If you want to get a head start on them, you can plant them indoors, about 10 weeks before your last frost date.
However, they are also perfectly fine for direct seeding into your garden. Try to plant them outside around your last frost date but if you get them into the ground earlier, they will be fine with a mild frost.
Indoor growing should start with sifted potting soil that is in small growing containers. Space your leek seeds about one inch apart.
Add a thin layer of soil over top. Do your best to keep the soil nice and moist which may mean daily watering.
Your seedlings will need warmth to begin germinating, so place your tray near a windowsill that gets plenty of sunlight. Just make sure the window isn’t too drafty if it is cold outside.
Even though you will be excited to see growth, it’s actually recommended to frequently trim the tops of your leeks. Leave about two inches of growth and cut the rest back weekly. This will force the energy back into the roots and make them stronger for later growing.
Your leeks are ready for transplant once the threat of frost is over, although you can take a risk and plant a few weeks earlier if you want. Add plenty of compost to the soil to make it rich in nutrients.
Transplant your small leek plants to your garden and space them so they are about six inches apart. The holes should be the same depth as the entire leek plant so that the roots reach the bottom of the hole and the tops of your leek plants are level with the ground.
Instead of filling the hole with dirt, you actually want to fill it with water instead. This will force the leek stems to swell and grow larger so that you have a longer vegetable to use. You can then leave the holes as the soil will naturally fall in time.
Leeks love sunshine, so find a bright spot in your garden for the vegetable. If they aren’t exposed to enough sun, the tops of the plant can become weak and topple over.
How to Water Leeks
Start by watering your leeks once a week. This should be a long and deep watering to help the roots, which are naturally shallow, grow deeper into the soil.
As spring turns to summer, you will need to water more frequently, especially during hot spells.
How to Grow Leeks
Adding a layer of bark mulch around your leeks will benefit them in many ways. First, it will prevent weeds from popping up. This is important as leeks have shallow roots so they can be hard to weed.
Second, mulch will help retain moisture in the soil. If you have very warm summers, having the extra moisture in the bark mulch will allow you to go longer between watering.
Finally, adding bark mulch in the fall will help to insulate the roots of your leeks. Then, even if it starts to get a lot colder, your leeks will keep growing until the winter.
Pests and Diseases
While leeks don’t attract too many pests, there are a few to be aware of. Maggots are the most common but this can be easily treated with neem oil to prevent the maggots from coming back.
As for disease, be aware of downy mildew or white rot. These are usually a result of damp weather, so help your leeks out by planting them in soil that drains well and keeping good airflow between the plants.
It might be hard at first to determine when your leeks are ready for harvest. Unlike onions, which die back when they are ready, leeks will simply keep growing.
Wait until your leeks are an inch wide before harvesting them. You can then remove them from the soil by twisting and pulling them out.
You can start to harvest your leeks in mid to late summer. If you live in a warmer climate, leeks will be available throughout the fall.
If you love the idea of reusing what is around you, or you just want a fun science experiment for your children, you can get into the habit of propagating your leeks.
Start by taking a healthy leaf from your main leak plant and ensure its stem and roots are still intact. Then, cut the leaf so that it is only an inch taller than the roots.
Fill a glass with clean water and put the roots into the glass. You want the roots to be in the water but not the stem.
Place the glass on a windowsill and change the water every few days. Within a week there will be new growth.
You can then choose to enjoy the leek you grew inside or plant it back in your garden for a larger leek plant.
Even though leeks can withstand some coldness, once the ground starts to freeze, they will no longer grow. If you are approaching the early days of winter, it is best to harvest what is left. You can then use or freeze the leeks for later use.
Those that live in warmer climates that don’t get freezing winter temperatures will be able to grow their leeks in the winter. You can help them out by growing them in raised beds which will increase the soil temperature.
How long do leeks take to grow?
Leeks take quite a while to grow but if you are patient, you will be rewarded with a long harvest season. Leeks should be started indoors, about 10 weeks before the last spring frost date. For many areas, this is in February.
The leeks are then transplanted outside in April or May. Then, they will be ready for harvest in late summer.
Leeks will continue to grow, however, well into fall and sometimes even early winter. So, even though you need to wait months for them to be ready, you then have months to harvest and enjoy them.
Leeks are often described as the sweeter version of onions. Plant them indoors in February before transplanting them outdoors in April or May. Then, once they are at least one inch thick, you can start to harvest them.