Kale is an easy-to-grow vegetable that you can harvest for a fairly long period of time, especially over the cooler months. But, you might be wondering how long it actually takes to grow kale.
To harvest your first leaves, it will take around 55 to 75 days if kale is grown from seed. If you transplant seedlings into your garden, you should be able to harvest your first kale leaves within 30 to 40 days.
Remember to harvest all your leaves from the bottom up so that your plant will continue to produce more fresh, tender leaves for a continuous harvest.
Let’s look at whether to grow kale from seeds or transplanted seedlings and the difference that it makes.
How Long Does It Take To Grow Kale From Seed?
If you plant your kale from seeds directly into a garden bed, you should be able to harvest your first edible leaves in 55 to 75 days. Generally, your seeds will start to germinate within 5 to 8 days.
When sowing your seeds, make sure that you prepare the soil well. It’s advisable to add some compost or organic fertilizer such as animal manures or bonemeal to give your seeds a good head start.
Seeds should be planted no deeper than 1/4 inch (1 cm) below the soil surface. If you plant the seeds too deeply, they’ll run out of energy before the shoots can emerge from the soil. Because kale plants can grow quite large, the seeds should be sown around 12 to 18 inches (30 to 45 centimeters) apart.
Depending on the temperature, kale seeds can take up to 2 weeks to germinate, especially if the soil is cold. If you want a fall harvest, you should plant your seeds into the soil in late spring or summer. This should speed up seed germination as the soil temperature will be warmer. Before you do this, though, put the seeds into a moistened paper towel and place this in a plastic bag. Then, put the seeds into the refrigerator for five days before you sow them into the warm soil.
You can also plant seeds in the fall to give you a winter crop if your climate is reasonably mild. Kale is fairly frost tolerant, and the leaves will be a little sweeter if they’re exposed to light frosts. However, if your area receives heavy snow coverage, you can cover your emerging seedlings with straw, and they will start to grow again in the early spring.
Kale Growth Phases
Like many other vegetables that we grow, kale has several distinctive growth phases before it’s ready to harvest. These phases start from when you plant the seed. Here’s an explanation of the different phases of growth.
- Seed sprouting phase. This is when the seed germinates and starts to produce tiny roots and a shoot. This can take around 5 to 8 days, but some seeds may take up to 14 days to germinate. Planting your seeds in friable soil with added organic matter will help the germination process. Kale will also germinate faster in warm soil with a temperature of around 20 degrees Fahrenheit (-7 degrees Celsius).
- Seed leaves phase. When the seeds start to germinate, they’ll usually sprout two leaves. These are referred to as the cotyledons and are part of the embryo of the seed. Quite often, they’ll look entirely different from the mature leaves of the plant.
- True leaves phase. The next phase of the plant is when you’ll start to see the first true leaves growing. At this stage, the roots of the plant are starting to provide nutrients to the green growth above the soil.
- Mature phase. After about six weeks of growth, your kale plant will have started to grow several leaves, and this is when you can start to harvest a couple of leaves from the bottom of the plant. Make sure that you don’t harvest leaves from the top. Otherwise, your kale plant will stop growing.
How Long Does It Take To Grow Kale From A Transplant?
If you decide to grow kale from transplanted seedlings, you should be able to harvest your first leaves within 30 to 40 days. You can either choose to start your seedlings indoors or purchase some ready-grown ones from your local garden center.
If you’ve grown your kale seedlings indoors, you’ll need to harden them off before you can plant them in the soil. You do this gradually over around five days. In the early morning, place your seedlings outdoors for a few hours and then bring them in again.
Do this for around five days, extending the time outside each consecutive day. This gets the plants used to the variance in temperature outside. Once your seedlings have spent all day and night outdoors, you can safely plant them in the soil.
Just dig a hole that’s large enough to accommodate the root ball and place each seedling inside its hole. Follow the same spacing as you would for sowing seeds. Be careful not to plant the seedlings too deeply. The bottom of the stem needs to be level with the surface of the soil.
Remember to keep your plants well-watered as they’re establishing themselves in the ground. After about 30 days, you should be able to harvest the lower leaves to use in your cooking.
Kale Life Cycle: How Long Is It?
Kale is a biennial plant. This means that it takes two years for it to complete its entire growth cycle from seed back to producing seed again.
Depending on your local climate, you can harvest kale for many months, especially over the cooler months. If you plant your kale in late spring to summer, you should be able to continuously harvest from early fall and right throughout the winter if your area doesn’t receive a heavy covering of snow.
However, if you do live in a really cold climate zone, your kale is likely to go dormant during the coldest period, but it will regrow in early spring when the snow starts to melt.
In warmer climates, kale is best grown throughout the fall, winter, and spring for the best quality leaves. Once the weather gets too warm, the plant will start to bolt and produce flowers and, ultimately, seeds. When this happens, the leaves will be a lot tougher and might start to taste bitter.
Should I Plant Kale Seeds Indoors Or Outdoors?
Whether you plant your kale seeds indoors or outdoors really depends on the time of year that you’re sowing your seeds. If you’re planning for a harvest in fall and winter, then you can safely start your seeds outdoors in early spring to mid-summer.
If you’re going to be planting your seeds in warm soils in summer, then you need to chill them in the refrigerator for five days before sowing. Seeds sown in early spring to early summer generally don’t require pre-chilling.
On the other hand, for an earlier harvest over the warmer months, you should start your seeds indoors around the middle of winter or four to six weeks before the last frost. You can then plant out your seedlings when the soil temperature reaches around 50 to 85 degrees Fahrenheit (10-30 degrees Celsius).
To learn more about this topic, please check out the article I wrote about growing parsnips from seeds.