蜜桃恋人

How to Grow Kale: The Complete Guide

Photo Credit
Beeldbewerking/GettyImages
Botanical Name
Brassica oleracea var. acephala
Plant Type
Vegetable
Sun Exposure
Full Sun
Part Sun
Soil pH
Neutral to Slightly Alkaline

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Planting, Growing, and Harvesting Kale

Catherine Boeckmann

Ever been told to 鈥渆at your greens?鈥 Kale is one of the most nutritious vegetables you can grow. It鈥檚 crammed with vitamins and powerful antioxidants, and it tastes de-licious. Kale is a hardy cool-season crop that grows best in spring and fall, tolerating frost and even snow. Learn how to plant, grow, and harvest kale. 

About Kale

Kale is a cold-hardy, resilient, non-heading green. It’s one of the easiest members of the brassica family to grow (which includes cabbage, broccoli, brussels sprouts, and other common cole crops.)

A biennial (2-year) plant, kale produces leaves in the first year, and then, in the next year (or sometimes late in the first year), it will form a flower stalk. The stalk forms flowers and then seeds. Once the seeds mature, the plant dies.

Think beyond grocery store kale; there are so many amazing kale flavors and textures to choose from if you grow your own seed: mild, almost salad-like greens, sweet 鈥楻ed Russian鈥 kales, or the nutty and sometimes peppery flavors of Italian kales, or handsome 鈥楥avalo Nero鈥 or Tuscan kale, also called dinosaur kale because of its texture.

As well as being extremely nutritious, kale is attractive, coming in a stunning range of varieties, from bright greens to dark purples, crunchy leaves to crinkled beauties, and everything in between. Its ornamental value can be appreciated in traditional garden beds or containers, especially in the fall.

While easy to grow, there are a few crucial things to get right if you want to enjoy a truly bumper crop of health-boosting leaves. Read on for our guide to growing kale.

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Planting

Full sun and fertile, well-drained soil produce the fastest-growing and most tender leaves, though kale will tolerate partial shade as well. Add plenty of compost to the ground before planting and if your soil isn鈥檛 especially rich, top up its fertility by working in nitrogen-rich amendments such as blood meal, cottonseed meal, or composted manure into the ground before planting.

When to Plant Kale

Kale tastes best when plants grow rapidly and mature before the heat of summer (before temperatures exceed 75掳F/24掳C) or after fall frosts occur. Young plants are not seriously damaged by temperatures down to 25掳F/-4掳C. Mature plants are extremely hardy and can withstand very cold temperatures. However, hot temperatures will slow growth and cause a bitter flavor.

  • For spring: Whether direct seeding into the soil or transplanting start plants from the nursery, you can plant 4 to 6 weeks before the average last spring frost. Seeds will germinate at soil temperatures as low as 40掳F/4掳C.
  • For fall: Select early maturing cultivars and direct-seed 3 months before the first fall frost date. Note: In areas with hot summers, you鈥檒l need to delay sowing until temperatures start to cool off. The cool fall weather really brings out the sweet, nutty flavor of kale which can withstand hard frosts (25鈥28掳F) without experiencing damage. 
  • Kale can also be grown as a winter vegetable under cover or outside in mild winter regions, like the Southwest, Pacific Northwest, and Southeast. They’ll grow and yield all winter long. We suggest speaking to your local cooperative extension to determine if/when you should plant winter vegetables.

How to Plant Kale

  • When planting, add fertilizer (1-1/2 cups of 5-10-10 fertilizer per 25 feet of row) into the top 3 to 4 inches of soil. If you fertilize with compost, apply no more than 1 inch of well-composted organic matter per 100 square feet of garden area.
  • Plant seeds 1/4 to 1/2 of an inch deep, 1 inch apart, in rows 18 to 30 inches apart.
  • If you’re setting out young plants (transplants), plant them at the depth at which they are growing in the container, spaced 12 inches apart, in rows 18 to 30 inches apart.
  • After planting, water the plants well.

See our video for growing perfect kale every time!

Growing

  • After about 2 weeks, thin seedlings to 8 to 12 inches apart.
  • It’s important to keep kale well watered and fertilized. If rain is inconsistent, provide 1 to 1.5 inches of water each week (about 1 gallon per square foot). 
  • Side-dress as needed with a high-nitrogen fertilizer.
  • Mulch the soil to keep down the weeds, retain moisture, and keep kale cool. Kale growth can slow if plants are stressed (too hot or cold, inadequate water, pests or disease). 
  • To guarantee a supply of mature leaves through winter, mulch heavily after the first hard freeze.

Types

  • 鈥楻ed Russian鈥 (or 鈥楻ussian Red鈥):  heirloom; oak leaf-shape, gray-green leaves with deep-purple veins and stem; an early crop
  • 鈥楲acinato鈥 (aka 鈥楲acinato Blue鈥, 鈥楾uscan鈥, 鈥楤lack Palm Tree鈥, or 鈥楥avil Nero鈥): heirloom, straplike leaves up to 2 feet long on plants that resemble small palm trees; heat tolerant and very cold-hardy.
  • 鈥楾rue Siberian鈥: large, frilly, blue-green leaves; cold-hardy; pick all winter in some areas
  • 鈥榁ates Blue Curled鈥: hardy variety that is slow to bolt and does not yellow in cold weather. It eponymous leaves reach 12 to 14 inches on 15-inch plants
  • 鈥榃颈苍迟别谤产辞谤鈥: resembles 鈥榁ates鈥, with 24-inch leaves on 2- to 3-foot-tall plants; baby leaves can be harvested at 28 days; frost-tolerant

Kale varieties

Harvesting

  • Kale is ready to harvest when the leaves are about the size of your hand. Pick about a fistful of outer leaves per harvest, but no more than one-third of the plant at one time.
  • Avoid picking the terminal bud (at the top center of the plant), which helps to maintain the plant鈥檚 productivity.
  • Kale will continue growing until temperatures reach 20掳F/-7掳C. Do not stop harvesting: A 鈥渒iss鈥 of frost makes it even sweeter. (See local frost dates.)
  • To extend the harvest, protect with row covers or tarps. Or, create a makeshift cover of old blankets propped up by hay bales. 
kale in snow
Kale is very cold hardy!
Photo credit: Beeldbewerking/GettyImages

 

How to Store Kale

Store kale, like other leafy greens, in a loose plastic bag in the refrigerator. It should keep for about 1 week.

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Wit and Wisdom

  • Kale is not native to North America. Current varieties are descended from wild cabbage.
  • Farmers have long grown kale as fodder for farm animals, including cattle and sheep.
  • Kale has a number of health benefits, as it is rich in minerals and vitamins A and C.
  • To avoid pest and disease issues, do not plant kale or other cole crops in the same location more than once every 3 or 4 years.
  • The chill of a moderate frost or light snow improves the flavor of kale.

Pests/Diseases

Kale Pests and Diseases
Pest/DiseaseTypeSymptomsControl/Prevention
AphidsInsectMisshapen/yellow leaves; sticky 鈥渉oneydew鈥 (excrement); sooty, black moldGrow companion plants; knock off with water spray; apply insecticidal soap; put banana or orange peels around plants; wipe leaves with a 1 to 2 percent solution of dish soap (no additives) and water every 2 to 3 days for 2 weeks; add native plants to invite beneficial insects
Black rotFungusYellow, V-shape areas on leaf edges that brown and progress toward leaf center; leaves eventually collapse; stem cross sections reveal blackened veinsDestroy infected plants; choose resistant varieties; provide good drainage; remove plant debris; rotate crops
CabbagewormsInsectLeaves have large, ragged holes or are skeletonized; heads bored; dark green excrement; yellowish eggs laid singly on leaf undersidesHandpick; use row covers; add native plants to invite beneficial insects; grow companion plants (especially thyme); spray Bacillus thuringiensis (Bt)
Flea beetlesInsectNumerous tiny holes in leavesUse row covers; mulch heavily; add native plants to invite beneficial insects

Recipes

Potato and Kale Soup
Kale Salad with Cranberries, Feta, and Walnuts
Kale, Sausage, and White Bean Soup
Hearty Kale, Bean, and Zucchini Soup

Cooking Notes

The small, tender leaves can also be added raw to salads or smoothies. Cut and cook the larger leaves like spinach, but be sure to remove the tough ribs before steaming or stir-frying. Kale can also be substituted for spinach in omelets, casseroles, and quesadillas. Enjoy our best kale recipes.

If you find the taste of raw kale to be too bitter, try giving it a massage. Remove stems and then chop leaves into pieces. Add a small amount of lemon juice or olive oil, then use your fingers to rub the leaves together for several minutes until the kale begins to wilt.

Also, kale is great for freezing. See how to freeze kale and other greens.

Vegetables
About The Author

Catherine Boeckmann

Catherine Boeckmann loves nature, stargazing, and gardening so it鈥檚 not surprising that she and The Old Farmer鈥檚 蜜桃恋人 found each other. She leads digital content for the 蜜桃恋人 website, and is also a certified master gardener in the state of Indiana. Read More from Catherine Boeckmann
 

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Comments

Helen Jaskoski (not verified)

4 years 3 months ago

About 5 or 6 years ago I bought a perennial kale in 4" pot. It has survived, thrived, and been divided numerous times since then. Takes cold & snow well. Milder flavor than cavalo nero ("dinosaur") and slightly more tender leaves. A nice ornamental as well as edible.

Kristan (not verified)

4 years 4 months ago

So last year I had giant beautiful Kale plants. They overwintered and held out pretty decent. Then they flowered and went to seed. I meant to gather the seeds before they all fell but got sidetracked. So my dirt is full of Kale seeds. It's mid summer, July, here. Can I just stir some of what's on the ground into the dirt and water and have new Kale for the rest of the summer? Thanks!

Hi Kristan,
As long as the temperature is between 60 and 85 degrees F, you can be fairly certain your seeds will germinate in the soil and sprout again!

Thomas Humphrey (not verified)

4 years 4 months ago

A neighbor (novice gardener) has several large kale plants, though they look rather ragged in July. (Live in Tennessee). Says her daughter bought the seedling plants, but she is going to destroy them because they are not the 'curly kind' of kale she likes and are broad-leafed instead. I told her, well, if you're going to rip them up, i might try replanting in my garden to see if they'll survive the winter. (Read here that kale is a biennial -- and i'm non-discriminatory insofar as kale varieties go.) OK, she says, but lemme know in a week or so or they're gone. Worth the effort?

If you’ve got the space for it, sure! Try planting in a place that gets partial sun, as full summer sun may be too much for transplanted kale. If it survives, you should get more growth as the weather cools in late summer and fall.

Jannie Lloyd (not verified)

5 years 4 months ago

I live in central France and, at the moment, we are in the middle of a Drought Crisis with daily temperatures in the high 30's/low 40's 掳C. I have an 18 metre long poly tunnel that I am watering with used bath water as the water table is so low. The tunnel runs, more or less, East to West with the beds going North to South across the tunnel. I mulch my beds with the old straw bedding from the rabbits / hens / ducks and most of the veg seems to be surviving.
The other day I was given a packet of Curly Kale seeds. I've never grown them before so I'm looking for pointers as to (1) when to plant the seeds and (2) how to care for them. Any advice greatly welcome.
Thanks in advance
Jannie

Loren Brauner (not verified)

5 years 7 months ago

I live in SoCal and we don鈥檛 get frosts at all. Can I 鈥榮imulate鈥 a frost by either putting the leaves in the freezer or dumping ice to melt around the leaves?

Dan Omlor (not verified)

5 years 5 months ago

No. When the PLANT experiences cold weather and/or frost or snow, it responds by adding sugar to its fluids. The sugar acts as an antifreeze to protect the veins, stems and leaves from freezing. WE like it because it makes the leaves sweeter but the plant could care less what we think. Your putting the leaves in the freezer has no effect on the plant because you've already picked the leaves. Dumping ice around the leaves would also have zero effect. It's the roots and stems which are sensing the cold and producing the sugar. IF you were raising Kale indoors or in a greenhouse in water ("Hydroponics"), you could chill the water down to 33 degrees and stimulate the Kale to produce the sugar. But that would be a very elaborate and expensive way just to get sweeter Kale and would hardly be worth it.

Kamie Mulroy (not verified)

5 years 8 months ago

How deep does the soil in the raised bed need to be to grow kale

Soil should be 12 to 18 inches in depth.  Till the soil to a depth of 6 to 8 inches