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How to Grow Kale

Caren White is a Master Gardener and instructor at Home Gardeners School. She has been associated with Rutgers Gardens for over a decade.


The first time I grew kale, I knew nothing about it. I had heard about it, but I had never eaten it nor ever seen it. I was gifted a couple of plants by a fellow gardener. I planted it, watered it and waited to see what happened. It grew quite tall with large broad leaves. I knew that a lot of people hated the taste of kale, so I decided to make spicy kale chips from it hoping the spices would mask the taste if it was not to my liking. They turned out to be delicious. I was telling a friend about it, and she said that she loved kale, especially the curly type. The curly type? There was more than one kind of kale? I had a lot to learn.

Curly Leaf Kale

Curly Leaf Kale

What is Kale?

Kale (Brassica oleracea var. sabellica) is a cool-season plant that is a member of the brassica family and is closely related to cabbage. It’s a non-head forming type of cabbage. It has been grown and eaten for thousands of years in Europe and Russia. The Europeans brought kale to America in the 16th century. Russian traders brought it to Canada in the 19th century.

Kale is a biennial that is usually grown as an annual. It is a cool season plant that does best in the spring and the fall. Optimal soil temperature is 60⁰F to 65⁰F. The soil should be rich in organic matter and high in nitrogen since you are growing it for the leaves. Make sure you have enough room in your garden. There are many varieties, but in general the plants are 2 feet tall and 1 to 3 feet in width. You can start your seeds indoors or direct sow the seeds into your garden.

The plants are categorized by the shape of their leaves:

  • Curly Leaf
  • Bumpy Leaf
  • Plain Leaf
  • Rape Kale
  • Leaf and Spear

Rape kale is a hybrid cross between kale and a leafy green known as Forage Rape. It is nick-named “hungry gap” because kale grows into the winter when there is little left in the garden to harvest. Leaf and Spear Kale is a hybrid cross between Curly Leaf and Plain Leaf.

Rape Kale

Rape Kale

What is Ornamental Kale?

Ornamental kale is a kale that is grown for its colorful leaves which grow in the shape of a rosette. The leaves can be white, red, pink, lavender, blue or violet. Because it can be grown in cold weather, ornamental kale adds color to gardens and landscapes when other flowers have succumbed to the cold. The plants are edible but are not usually eaten.

Ornamental Kale

Ornamental Kale

How to Grow Kale From Seed

To start seeds indoors, plant them 6 weeks before your last frost. They should be planted ½ inch deep. Germination should occur in 5 to 8 days. You can plant your seedlings in your garden after all danger of frost. Space them at least 16 inches apart. They should be ready for harvest in 30 to 40 days.

To direct sow your seeds, soil temperature in your garden should be at least 45⁰F. Plant the seeds ½ inch deep. Germination will be slower than indoors because of the cool soil. Once the plants have germinated, thin them after two weeks so that there they are at least 12 inches apart. They should be ready for harvest in 55 to 75 days.

Give your plants 1 to 1 ½ inches of water per week. As the season progresses and the soil warms, mulch your plants with a thick layer of straw to keep the soil cool. Cover them in the beginning of the season to protect the young plants from the cold. Once the summer heat sets in, the plants will stop growing and producing new leaves. It’s best to remove them from your garden to make room for heat loving veggies.

For a fall harvest, sow seeds directly into your garden 6 to 8 weeks before your first frost. The seedlings will grow slowly at first in the summer heat. Once the cool temperatures of fall set in, the plants will grow much more quickly. If you prefer to grow your fall kale from plants, you can plant the seedlings in your garden 3 to 5 weeks before your first frost. Mulch your plants to protect the roots from the summer heat. Give them 1 to 1 ½ inches of water per week.

Bumpy Leaf Kale

Bumpy Leaf Kale

How to Harvest Kale

Kale is ready to harvest when the leaves are the size of your hand. Always harvest from the bottom of the plant, leaving the top leaves and terminal bud intact. This is where the plant is actively growing. If you cut off those top leaves and the bud, the plant will stop growing and producing leaves. Once you have harvested from a plant, it will be ready for harvest again in 5 to 7 days. If you use a lot of kale, plant enough plants so that you can have daily harvests.

In the spring, you can continue to harvest your kale until the heat of summer when it will stop growing.

In the late fall you can continue to harvest your kale after a hard frost and right up until the ground freezes. The plants will survive down to 20⁰F. Kale tastes better after a frost. You can try to extend your season by covering your plants with a floating row cover or even a tarp.

How to Store Kale

You can store kale in a plastic bag in your refrigerator like any other leafy green. It will last 1 week.

© 2018 Caren White


Caren White (author) on January 17, 2018:

Marlene, I love adding spices to my kale chips. I would never have thought of cooking them in the microwave. Thanks for the suggestion!

Marlene Bertrand from USA on January 17, 2018:

Kale is one of my favorite plants to grow and eat. I recently learned how to make kale chips in the microwave. Dry the leaves, break them into chip-sized pieces and place single-layered on a microwave safe plate. Sprinkle a little oil and salt over the kale. Pop the plate of kale leaves into the microwave for one minute and you will be amazed at how crunchy they are.