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

DEVA MOODLIAR (not verified)

6 years ago

I have kale plants that have formed a cabbage above ground with roots in the soil and healthy leaves growing on the cabbage like kale leaves.IS THE CABBAGE EDIBLE and how to cook it.

Kale plants don’t typically form heads (the cabbage-like structure that forms in the center of the plant), but since kale is just a type of cabbage, it can happen! The kale head is edible, but I’m not sure how it will taste鈥攊t could be bitter or overly tough. Try a piece raw first, and if that’s not very satisfying, try boiling it (here’s a corned beef and cabbage recipe to try). Also, note that kale often tastes a bit better after a frost, so if you’ve got a frost coming soon, wait until afterwards to harvest the plant. Let us know how it turns out!

Bec (not verified)

6 years 6 months ago

There is a tall raised flower bed at the back of my house that was built with a plywood or Particle board type wood wall faced with brick. The wood was sprayed with bug spray and hornet/wasp spray. I was not thinking about this when I got plants but I planted kale and strawberries in the bed. I don鈥檛 know if the sprays leached into the soil?? Are they safe to eat? Or are they all just a waste? Will they ever be safe? I am usually pretty picky about my own food and spray choices so I don鈥檛 know what to think about this? Any advice? Thank you

Roger Hansen (not verified)

2 years 8 months ago

Most pesticides break down rapidly in sun light & rain. If, you're still concerned, just plant flowers in that location & grow your veggies somewhere else. Two kale plants will probably produce all the kale you can eat & won't require much space.

Plywood may contain/be treated with copper azole. You can learn more about this here: https://www.extension.iastate.edu/smallfarms/toxicity-concerns-about-raised-bed-construction-materials  Particle board is not mentioned on that page but we would avoid it. As for the bug spray you need to read the can/container; usually there are advisories on such products. Without knowing what chemicals it contains, we would only be guessing. That said, we would propose that you might be able to transplant the kale and berries. Hard to know how far along they are but if you get a new, safe, clean plot ready and get it done and then provide lots of TLC, you might have a harvest after all. We hope this helps.

MGD (not verified)

6 years 6 months ago

Hello there,
We moved into our home a year ago and it has a lovely garden. One item is Kale and right they are huge plants and have a lot of flowers on them. From what I am gathering is that they are done? But I am not too sure what Bolting is? I was wondering if I need to cut them down and/or pull them out? They have survived all winter long and their leaves grew all year long. Any advice you can provide will be helpful

Kale is a biennial (2-year) plant, which means that it will produce leaves the first year, and then the next year (or sometimes late the first year), it will form a flower stalk. This stalk eventually forms flowers and then seeds; once the seeds mature, the plant dies shortly after. The act of forming that tall, central flower stalk is called bolting. Sometimes the bolting response in a plant can also be caused by other factors, such as temperature or stress. If your kale plant is bolting, and it is the second year, then the plant will not last much after the seeds form—you may want to pull it up and start over, unless you plan to collect seed (though if the kale is a hybrid, the offspring may not be similar to the parents). Once kale bolts, the leaves take on a stronger flavor, at which point harvesting usually stops. Hope this helps!

Sharon Hugh (not verified)

6 years 6 months ago

Hi ,
I am new to gardening and moved into a house with kale already growing. Stem is over 4' height, small and sparse kale leaves between growth spurts and has long shoots with yellow flowers on the top. Stem is so long & heavy, its dragging on the ground or about to.

Do I cut the entire stem off? Do I trim?
Help...please and thanks.

If this is edible kale, the yellow flowers are a sign that the plant is bolting. If you have not already, cut the stems that you want and save or cook them. You can cut the flowers for a vase or leave them for appearance, but as an annual, the plant is almost done.

Raquel Lovern (not verified)

6 years 7 months ago

Hi! My kale is starting to flower, am I supposed to pull the flowers off like for basil or broccoli?