How to Plant, Grow and Care For Kale in Your Garden

Cold-hardy, fast-growing, and nutrient-dense, kale is a cousin of cabbage that should be a staple in every garden. Plant it once and harvest all season long: kale is one of those generous crops that just keeps on giving.  

This vigorous brassica is easy to grow in the garden and versatile in the kitchen. Best cultivated in cool-weather seasons and climates, kale offers a sweet flavorful green that can be used in everything from soups and salads to smoothies and pestos. 

Whether it’s curly, ruffled, green, purple, or even ornamental, all kale varieties belong to the species Brassica oleracea. This species includes a wide range of kale-cousins as well, from bok choy to collards to broccoli and beyond, B. oleracea has found its way into nearly every cuisine in some way or another.  

Modern Trend With Ancient History 

Kale is one of the trendiest vegetables of modern times; you can find it in kale chips, green smoothies, “Buddha bowls”, and even on t-shirts. Though it has regained a lot of popularity in recent years, this lush vitamin-rich leafy green has been nurturing European cultures for at least 2,000 years.  

Ancient Romans grew several varieties of kale, collards, mustards, and primitive cabbage-like greens. Kale (“kail” in Scotland) is so ubiquitous in the traditional Scottish diet that the entire kitchen garden was typically referred to as a “kailyard.” And the classic collard greens that fill American southern cuisine are actually just another close cousin of kale.   

Wild European Roots 

Brassica oleracea started out as a wild mustardy cabbage green native to coastal southern and western Europe. Its ability to grow in harsh cold winters has garnered this plant plenty of popularity in the northern climates of Scotland, Russia, Scandinavia, and Canada. It grows happily in most regions of the United States, except during the hottest parts of southern summers. 

Unlike its wild cousins, kale has been traditionally bred (no genetic modification here!) to have a sweeter, more mild flavor without the spice of wild mustards. It also has been selected for traits like a more bushy habit, unique leaf shapes, and a resistance to bolting (going to seed) in hot weather. 

Kale Has 100+ Cousins 

As a member of the Brassicaceae, or “cole” family, this species includes hundreds of cultivated varieties of cabbage, broccoli, romanesco, cauliflower, brussels sprouts, turnips, radishes, rutabagas, mustards, tatsoi collard greens, kohlrabi, and of course, our beloved kale. Wow, that’s a big family! 

Basically, the original wild variety has been selected and bred for all sorts of different traits that differentiate these “cole crops” from each other. Cabbage has been bred for close-together leaves that curl into large heads. Brussels sprouts have been selected for small cabbage-like balls growing along a tall stalk. Collard greens are flatter, wider, and more amenable to sautees or slaws. The coveted kale plant has been bred to come in all shapes, sizes, and colors, most notably the curly rumpled greens we find in restaurants and supermarkets.  

A Nutritional Powerhouse 

There is no denying kale is a nutritional powerhouse. It is rich in vitamins K, C, and A, fiber, carotenoids (including lutein), vitamin B6, and trace minerals like manganese. Thanks to the high amount of antioxidants, kale is known for relieving inflammation in the body.  

It also has sulfur-containing compounds called isothiocyanates that help the body detoxify from harmful substances. Because of the high fiber content, many people may prefer to slightly wilt or cook their kale to make it more easily digestible than raw kale.  

Thanks to all the kale hype in recent years, many studies have been conducted on this lovely brassica to reveal an abundance of health benefits. Kale detoxifies your body, slows aging, provides antioxidants, improves brain health, enhances eye health, and even helps fight cancer. 

Cancer-Fighting Green 

Like many cruciferous vegetables, kale has extraordinary cancer-fighting abilities. Sulfur-containing compounds called isothiocyanates and glucosinolates help prevent and inhibit the development of cancer in several organs, including the bladder, breast, colon, liver, lung, and stomach. Kale helps protect cells from DNA damage while simultaneously inactivating carcinogens.  

While the specific mechanisms of these processes aren’t fully understood, scientists agree that eating this vitamin-rich green is part of a healthy diet. Better yet, grow it in your garden and toss it into meals throughout the week to enjoy plenty of the health-promoting benefits of kale. 

Propagation and Planting 

Kale is a really easy plant to grow for beginner gardeners. The most important step is ensuring you have happy seedlings to start with. If you provide plenty of water and a little bit of fertility, kale will keep on growing all season long. If you live in a hot place, you may want to plant two successions of kale: one in early spring and a second in early fall for winter harvests. 

How Long Does Kale Take to Grow? 

Most kale varieties mature to full size in 50 to 65 days. If you are transplanting, subtract 14 days from the seed packet “days to maturity” number.  

Baby kale greens can be grown in as little as 20-30 days. Kale microgreens take just 10-15 days.  

Transplant or Direct Seed? 

Kale can be grown as singular full-size bunching plants to harvest from all season long. Or you can grow baby kale and microgreens for use in salads.  

Full-size kale is typically transplanted, whereas baby kales are directly seeded in the garden. You can direct seed bunching kale as well, but it will require thinning and may not yield as quickly. 

Kale microgreens are usually grown indoors in trays or flats inside a greenhouse or under grow lights. 

How to Transplant Kale 

Start kale seeds in the late winter or early spring, about 4 to 6 weeks before the last frost. Sow 2 seeds per cell in 50 or 72-cell plug flats. 

While these plants are incredibly cold-hardy, it is best to give baby kale starts some time to develop their leaves and roots before subjecting them to the cold. Wait until seedlings have 3-4 sets of true leaves and have thoroughly rooted out their cell containers, you can transplant them in the garden.  

Holding the base of the plant, gently wiggle the root ball out of the cell container and place it in a similar-sized hole in your garden bed. Gently backfill, keeping the surface of the seedling level with the soil surface. Thoroughly water the baby transplants and protect them from pests and frost with a floating row cover, if needed. 

Spacing for Full-Size Kale 

For large lush kale plants, space transplants at least 12-18” apart in rows 18-24” apart. Plants can be grown closer together if you are low on space, however, the leaves may be smaller. Small gardens may opt for 1 square foot of space for each kale plant.  

How to Direct Seed Kale in the Garden 

Wait until soil temperatures are approximately 45°F in early spring. Use a soil thermometer to gauge when it is warm enough to germinate brassica seeds outdoors.  

Direct seed kale in outdoor beds by making a small furrow and sowing seeds ¼” deep, then gently backfill and tap down to keep seeds in place. Keep consistently moist for 5-10 days until seedlings are germinated. Do not let the soil dry out.  

Floating row cover over the germinating kale seeds is ideal for keeping them moist while simultaneously protecting them from frosts and pests like flea beetles.  

Spacing for Baby Kale 

Baby kale can be sown at a rate of 3-5 seeds per inch in rows 2” apart. Avoid seeding in temperatures above 75°F as seeds do not germinate well in the heat.  

It is best to seed it in a dense block for easy harvests and competition with weeds. If you sow baby kale too close together, it will not yield as consistently, whereas if it is too sparse there may be lots of weed competition or plants may grow too large to use as baby greens.  

How to Grow Kale Microgreens 

Popular amongst chefs and culinary enthusiasts, microgreens are simply infant kale plants that only ever get just past the cotyledon stage. They can be grown in a greenhouse, by a south-facing window in your house, or under grow lights. 

Begin with shallow trays or flats and a potting mix of your choice. Broadcast (toss) the kale microgreen seeds thickly on the surface, aiming for seeds to land about 1/8″ to 1/4” apart. Press them into the media for soil contact and then cover lightly with more potting mix or vermiculite. A humidity dome is also helpful.  

Keep the ambient temperature around 65° to 75°, but no hotter, or the seeds will germinate erratically. Provide plenty of air circulation to prevent disease. Water regularly until the soil is moist, but never soggy. Microgreens will germinate in 5-7 days and be ready to harvest in 10-20 days depending on the variety and desired size.  

Companion Planting 

Companion planting adds biodiversity and resilience to your garden by planting crops and flowers together for their mutual benefit. Some kale companions fix nitrogen and nurture the soil, while other companions act as insectaries or pest repellants.  

Being a brassica, kale is susceptible to a wide range of pests that we’ll go over below. One of the best things you can do to prevent pest issues in kale is to use companion plants that attract beneficial insects or repel the bad ones.  

The best companion plants for kale include: 

• White alyssum (attracts loads of beneficial predator insects) 
• Cilantro (especially if you let it flower) 
• Dill
• Lemongrass 
• Bush beans 
• Hot peppers 
• Scallions 
• Onions 
• Leeks (one of the best cold-hardy winter pals for kale) 
• Marigolds 
• Nasturtiums  

Avoid planting kale with: 

• Too many other brassicas (it’s best to rotate brassica family crops around the garden to prevent disease and pest issues) 
• Sunflowers (can prevent kale germination) 
• Tomatoes (can shade out or take nutrients from kale) 
• Strawberries (attract pests) 

Varieties 

Kale comes in a diverse variety of shapes, sizes, and flavors that are suited to different growing conditions and seasons.   

Curly Kale 

Curly kale is the most common variety that you will find in grocery stores. It has dense, vibrant dark green leaves that are ruffled and curled. They are pretty mild in flavor and grow in a nice whorl along a woody stem. Curly kale can also come in gorgeous red varieties. 

‘Westlandse Winter’ 

This vigorous open-pollinated variety has attractive blue-green leaves and a large, bulky growth habit. Matures in 60 days and yields large fluffy ruffled leaves.  

‘Darkibor’ 

A stouter, sturdy kale that’s great for windier gardens. This less curled variety has dark green leaves and takes 75 days to mature. Great for fall and winter harvests.  

‘Redbor’ 

A beautifully frilly kale with purplish-red leaves. Excellent flavor and vibrant color for adding a flair to meals. The flavor, color, and leaf curling are enhanced in cool weather. Very cold hardy and quicker to mature. 

Lacinato Kale 

‘Lacinato’ kale (sometimes called Tuscan or “Dinosaur” kale) is one of the trendier and tastier varieties. It is a deep blue-green leaf with an elongated shape and tender savoy texture that cooks perfectly into sautees. This variety originates in Italy and has been used in Mediterranean cooking for hundreds of years. 

‘Black Magic’ 

The classic uniform deep bluish “dino” kale that you find at popular farmer’s markets and restaurants. This variety has performed well on nearly every farm and garden I’ve visited in the United States. It is hardy, bolt-resistant, and yields consistently all season long. Open-pollinated and 65 days to maturity. 

‘Mamba’ 

An extra vigorous Lacinato-type that grows with an upright shape. The leaves are very savoyed and uniform for beautiful bunches to gift to non-gardener friends or fill your fridge with. The flavor is complex, mild, and earthy, especially in cold weather. 65 days to maturity.  

Russian Kale 

Russian kales are incredible fall and winter kale varieties with pale bluish-green leaves and red or purple veins. The leaf shape is flatter like a collard green, but with wavy serrated edges and a tender texture. This kale can survive down to a whopping -10°F and is a delectable treat in the dead of winter when nightly frosts have caused sugars to accumulate in the leaf cells. 

‘Red Russian’ 

This is the classic cold-hardy Russian variety that matures in 29 days for tender baby kale and 50 days for full size. It is a medium-tall plant with an open growth habit. Harvest purple-veined leaves from this kale all season long. Sweet, tender, and excellent in oil-massaged salads or winter stews. 

‘Russian Royale’ 

A lovely dark-purple Russian kale variety bred specifically for baby leaf production. Grow these baby greens in around 32 days and enjoy them as a vibrant salad or mix with other baby kale varieties. The leafy, deeply-toothed leaves have a light-green back and amazing flavor, plus downy mildew resistance.  

Ornamental Kale 

Believe it or not, kale isn’t only popular in the kitchen. I’ve started to see ornamental kale pop up in urban landscapes and flower gardens around the country. These kales are more cabbage-like than their culinary cousins. They look like cute little kale bouquets (and are in fact sometimes used in flower arrangements)!

Many have variegations in the inner versus outer coloring for a bright low-growing pop in any landscape. You can technically still eat them, but they aren’t very appealing compared to the culinary varieties described above.  

‘Crane White’ 

Rich green outer leaves with a creamy white center and blush of pink. This ornamental kale is used in landscapes and autumn bouquets. It takes 90-110 days to mature and yields 24” to 36” tall plants. 

‘Crane Feather Queen Red’ 

A super unique serrated frilly ornamental kale with vibrant magenta centers and Russian-style outer leaves. These add texture to autumn floral arrangements and gardens.  

Baby Kale and Microgreens 

Technically any variety of kale can be grown for “baby” sized harvests, but seed companies have recently started offering some great varieties bred specifically for tender small leaf harvests. 

‘Kalebration Mix’ 

My personal favorite: a gorgeous baby kale mix of brilliant reds and greens with many shapes and textures. It grows back again and again after cutting, so you can use the “cut and come again” harvest technique by cutting at the base of the stems (leaving the growing tip in the ground). It takes just under 30 days to mature and grows back in 1-2 weeks after each cut. 

‘Kalefetti’ Mix 

Vivid tiny kales perform really well in microgreen trays. Includes bright green, dark green, red, and purple varieties. The flavor is mild and refreshing. Only 10-15 days to harvest.  

Caring for Kale 

Kale is notoriously easy-going when it comes to garden care. Just a few simple tips will have your kale plants lush and thriving all season long.  

Water 

Kale likes consistency rather than large amounts of water at once. Maintaining a moderate level of moisture throughout the season will yield the highest quality kale leaves. Ensure that your soil is well-drained so that water does not pool up around the base of the plant, as this could cause root rot or clubroot (a disease described below).  

Soil and Fertility 

Like all brassica crops, kale prefers more bacterially-dominated soils (as opposed to acidic fungally-dominated soils). This is because their wild mustard relatives are typically found in grasslands rather than in forests. The ideal soil pH for kale is between 6.0 and 7.5, which is more alkaline. Avoid excessive woody mulches around kale that may contribute to a more acidic soil environment. 

In terms of fertilizer, kale is not a heavy feeder but it does like plenty of organic matter such as compost and a consistent source of organic fertilizer. Feed newly transplanted kale plants diluted fish and seaweed emulsion or a slow-release, all-purpose fertilizer to support them throughout the growing season.  

Mulching 

As mentioned above, it is best to avoid mulching kale with woody materials. Instead, opt for a fluffy seed-free straw or hay mulch, or better yet, use deciduous leaves collected in the fall to keep weeds from growing around younger kale plants. Even better if you can keep your vegetable mulch organic. Once kale gets large enough, it tends to shade out most weeds with a dense canopy, but the mulch can still be beneficial for conserving moisture in hot climates.  

Temperature 

At the germination stage, kale prefers soil temperatures around 70°F and ambient temperatures between 60° and 75°F. Once it is germinated, higher temperatures will actually stunt growth. Outdoors, kale prefers 40° to 65°F, but tolerates far down below freezing and even below 0°F if the plant is robust. It will tolerate warm summer temperatures but may bolt in the heat or have pest problems in southern summers.  

Sunlight 

Kale does best in full sunlight for at least 6 hours per day. It will tolerate light shade (4-6 hours of sunlight), but it’s best to plant in the sunniest part of your garden. Keep in mind that the sunlight shifts throughout the seasons, so if you hope to harvest kale through the fall in winter make sure that no trees or structures shade it out when the sun sits lower in the winter sky. 

Troubleshooting 

Kale is beginner-friendly and oh-so-common, but that doesn’t mean it’s immune to issues. The brassica family encompasses so many common garden crops that they have unfortunately become quite susceptible to many pests and diseases. But the best preventative step for all of these problems is simply to keep your plant healthy.

Nurture your garden soil with high-quality compost and no-till practices. Give the kale plenty of consistent water and light organic fertility. Keep weeds at bay so it doesn’t get stressed out. And monitor for problems so you can catch them early. 

Aphids 

These little white buggers are the bane of any gardener’s existence. They can eat just about anything but especially love kale. Find the tiny oval silvery-green bodies on the undersides of leaves.  

Aphids are nasty-looking, sap-sucking pests that reduce plant vigor and are not very appealing for eating. They also produce a sugary substance that may attract ants or encourage black mold growth on the leaf surface. Gross! 

Fortunately, no toxic chemicals are necessary for getting rid of aphids! One option is using a heavy-duty hose to spray the aphids off. You can also use water and non-toxic dish soap sprayed all over the leaves to suffocate and kill the aphids. Alternatively, you can soak tomato leaves in water and apply that solution to the kale plant. Tomato leaves contain alkaloids that are toxic to aphids but harmful to humans.  

If none of this works, simply apply a diluted neem solution to the leaf surface to kill and repel aphids. As a preventative measure, plant companion flowers that attract ladybugs to your kale plants. Some of my favorite ladybug-attracting plants are flowering dill, chives, yarrow, fennel, and alyssum. Ladybug larvae can eat up to 50 aphids per day.  

Cabbage Looper 

Sometimes called cabbage worms, these green caterpillars are the larvae of the white cabbage butterfly that you may see flitting around your garden. Cabbage worms are the most harmful in early spring when no parasitic wasps or other predators are out to control them. The best thing to do is handpick cabbage worms, use a row cover, or use the organic biopesticide Bacillus thuringiensis (Bt) to kill the caterpillars.  

Bolting 

Bolting happens when it gets too hot and kale plants go to seed. This changes the composition of the plant and leads them to reach upward to produce seeds and flowers, resulting in bitter tough leaves.  

If your kale plant begins bolting, you can try cutting off the center of the flower head to encourage it to stay in “vegetative” leaf production. Alternatively, grow bolt-resistant kale varieties that can tolerate hot weather. Or, if you live in a southern climate, simply avoid growing kale in the hottest months and instead opt for spring, fall, and winter kale.  

Club Root 

Club root is a fungal disease that affects the entire brassica, or cabbage, family. The symptoms are wilting (no matter how moist the soil), stunting, and swollen deformed roots. The best way to prevent club root is by ensuring you have well-drained soil and avoiding overwatering. Keep the soil rich in high-quality compost and a higher pH (because acidic soils favor the club root pathogen). 

Practice crop rotation and add plenty of diversity in your garden so that brassicas are not grown in the same place each year. If your kale plant falls victim to club root, it is best to simply remove it and plant new kale plants elsewhere in your garden. The pathogen lives in the soil for many years, so you will have to avoid brassica crops in that area.  

How to Harvest Kale 

Kale plants yield in abundance year-round in northern climates. In warmer southern regions, kale bolts (goes to flower) or slows down significantly during the summer. The flowering shoots and tops are edible and often sold as “kale raab.” However, keep in mind that heat makes kale more intense and bitter, whereas cold makes it sweet and pleasant.  

You can begin harvesting about two months after planting. To harvest kale, simply pull downward at the base of a leaf stalk and remove it from the stem. If your kale stems are not yet strong and hard, you may wish to use a knife or scissors for beginning harvests. 

Over time, kale should form a robust center stalk that can easily withstand repeated leaf harvests. In fact, the more you harvest your kale leaves, you will encourage it to grow in greater abundance.  

Harvest from the lower parts of the plant first and leave smaller growing leaf centers at the top to continue growing. By the end of the season, your kale plant may look like a silly curly-haired stick figure from a distance because of the bare stalk where you have harvested and the fluffy leaves remaining at the top.  

How Cold Hardy is Kale? 

Kale can survive full winters in USDA growing zones 7 and warmer. It may even tough it out and regrow in early spring in colder places. However, if you use mulches, frost protection blankets (row cover) or low tunnels, kale is hardy down to -10°F.  

For winter harvests, it is best to plant kale in the garden in late summer so it has plenty of time to get established before the frosts begin. Younger kale will be more fragile and susceptible to frost damage or death.  

Frequently Asked Questions 

Final Thoughts

Kale is a very beginner-friendly vegetable, that serves many different purposes. There are many different varieties to choose from, depending on your soil type, and geographic location. Kale companion plants very well with many different vegetables, making them an extremely versatile solution for gardeners looking to have a variety of different veggies in their garden.

After reading this guide, you should have all the information you need to plant, grow, and care for this nutrient-dense leafy green veggie!