Growing Kale: Grow Your Own Superfood

Ed Wike
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Quick Care Guide

Kale is one of the healthiest foods you can grow. It is rich in many health promoting nutrients and antioxidants, and there are many varieties with easy-to-hand characters that allow you to grow it almost anywhere.

Kale belongs to the cabbage family and is a semi-hardy, annual vegetable. It grows best in light, well-drained soils with a slightly acidic pH (6.5 to 6.8). Full grown plants reach at least 24" (60cm) in height, and have a leaf width of 12-36" (30 to 90cm).

Before planting, amend the soil with plenty of well-rotted manure and compost and rake the soil to a light tilth. Then sow seeds in a row, approximately 3" (8cm) apart and 1" (3cm) deep. Keep the soil lightly moist during germination, until seedlings are established.

Sow seeds in early spring and late summer to have kale ready for a fall harvest. It will thrive in average soil temperatures.

If you wish to succeed with kale, avoid the common mistake of over-watering. Watering in the morning is generally best, as it allows the roots to dry out over the day. It is also best to use mulches to prevent moisture from evaporating.

Good companion plants for kale are: garlic, onion, cabbage, lettuce, onion, tomato, and shallots.

With so many types of kale to choose from, how do you decide which kind to grow? The first step is to decide what type of kale you want to grow. Do you want colorful, curly leaves or tall, lanky leaves? Or do you just want to grow nutritional powerhouse?

For health and nutrition, curly-leaf and red (rubrum) kale are at the top of the list. Both are great for salads, stir-fry, soup, or sautéing It's easy to freeze either one, and they are a favorite ingredient for smoothies. Red kale is a pretty ornamental in the garden, too, and it's a great contrast plant for other leafy greens such as spinach, lettuce and kale.

If you're into ornamental kale, choose ornamental varieties. The most popular is red-colored ornamental kale known as purple kale. Other varieties have yellow, bronze or maroon colored leaf edges. The leaves of these colorful salad-type kale are tender enough that you can eat them raw and they have a mild kale flavor. Most ornamental kale has less fiber and nutrition than other varieties.

Curly-kale is probably the most popular to grow in a home garden. Both savoy and regular curly-kale have several varieties. The most popular is probably curly-kale-Russian Red, a beautiful ornamental and good for salad and stir-fry.

Curly Kales

The curly kale has a sturdy stem, yet is more tender with a milder flavor than its cousin. It can be used in a stir-fry instead of Chinese cabbage or in a salad for texture. You can also use it in a garden bed to add vertical interest instead of flat-leaf parsley or carrots.

Kale, "the king of all greens," is a delicious addition to any green-thumbed gardener's garden. Its tasty leaves can be harvested in abundance. With a minimum of care, you can expect to harvest the leaves for up to one hundred days, and sometimes longer.

There are a number of varieties of kale. Some of the more popular cultivars include the curly kale (also called Scotch Kale), flageolet ("little flags"), Nero di Toscana, and Red Russian. The Red Russian is the hardiest of the bunch, but it is not as tasty.

The leaves of this very nutritious superfood are similar to that of collards. When buying seeds for growing your own kale, you will notice that they are listed as "collards and kale." The main difference is that col- lards are more bluish in color whereas kale leaves are a more earthy green.

In any case, growing veggies from seed is a rewarding experience. Sowing them when the ground is still frozen will hasten the grow time, producing leaves about four weeks after the last frost.

Flat Leaf Kale

If you want the ultimate in convenience, you can opt for one of the pre-washed and pre-cut bags of kale available at most grocery stores.

Either way, growing your own kale is fairly easy. Kale grows best in full sun but will tolerate most conditions, including partial shade.

This versatile green is a kitchen mainstay, but it's also good for you. Not only is kale a great antioxidant, but it also contains as much or more iron as spinach. Vitamins A, C and K and cancer-fighting phytochemicals are also found in kale.

Growing kale also provides an edible privacy screen and attracts bees and butterflies to the garden.

Dinosaur Kale

Or Tuscan Kale?

Both of these varieties belong to the 'cavolo nero' species, and both are black-leafed forms of cabbage. Unlike traditional cabbage, which forms a heart, these varieties form dark, blue-green leaves.

It’s the flavor that separates them. With its powerful blend of vitamins and the kind of fiber that moves out of the body, it may just be the super green of the new millennium. Dinosaur kale has a stronger, more concentrated flavor than Tuscan. It's a great complement to bitter greens like chicory. Tuscan kale is milder, but it's hard to complain about either one. You can buy either one loose or in packets in nurseries usually, and both are varieties that grow exceptionally well in a garden.

Ornamental Kale

@@ Ornamental kale plants are attractive plants with large, heavily veined, dark green or purple leaves. They produce white flowers which are pollinated by bees.

Kale can be used as a free-standing feature in a pot or as an attractive ground cover. They look best growing up a trellis, they can grow to a height of about three feet. Ornamental kale does not produce edible leaves, but you can harvest the flowers for your salads.

Suitable for growing in containers, ornamental kale can also be grown in the middle of vegetable gardens.

While ornamental kale is great for adding texture, colour and year-round interest to your garden, it does not produce enough leaves for the human diet, so if you are looking for vegetables, grow different varieties.


If you are new to gardening, growing kale shouldn’t be your first venture. Wait until you’ve got some experience under your belt. Kale is probably more forgiving than other veggies, but it still needs some tender loving care to grow well.

Kale thrives in rich, moist soil. If you’re dealing with heavy clay soil, your best bet is to grow your kale in containers using a soil-less growing medium. Soil-less growing medium is basically a type of mulch that’s been pressed into a pot. It will allow your kale to have the texture and drainage that it needs without the hassle of adjusting your soil for a specific vegetable.

For containers, you can use just about any pot type around, even a large wine bottle if you’d like. If your container is clear, it will be easier for you to monitor the water level inside and to see if pests are lurking.

In most climates, kale is a great cold-weather crop that grows best in cooler weather. Before planting, prepare your soil by tilling it up. Tilling the soil will break it up, which makes it easier for your kale to grow roots.

When To Plant Kale

Kale plants prefer cold weather and this can help you know when to plant kale seeds. The best months are from October through January and seedlings can be planted after March. To be sure of the best weather, look for a day that has fallen temperatures between 60 and 75 degrees and after the last frost date. The soil should already be warm to reach the preferred temperature for sprouting in a day and if it is still too cold it can take longer to sprout.

Kale doesn't like the heat and can wilt if it is exposed to temperatures above 75 degrees in its baby stage. While kale can tolerate cool temperatures, it grows better in the sun and thrives in the temperature range of 60 – 70 degrees.

Next to soil, what is most important for your kale's health is mulch. Mulches like leaves and compost will help the cold from entering the soil and keep the weeds away. You will be able to keep the leaves and grass cuttings from your lawn and have them be ready to go for a future mulch.

Kale loves water and needs at least 1 inch of water a week to grow quickly and healthy. You will probably have to water more frequently than you think you need to and a good way to know if the kale is getting enough water is if it is growing new leaves.

Where To Plant Kale

Most of us assume that kale can only be grown in areas with a cool, moderate climate.

This is true as far as it goes. However, there are actually varieties of kale that grow very well in hot, dry areas.

How cool does it have to be to grow kale? Kale grows best at temperatures between 32 and 50 degrees Fahrenheit.

The most important factor is the length of the day.

Kale grows best in places where days are between 12 and 24 hours long.

In places where the day length counts in weeks (such as in tropical regions) kale does poorly.

Kale needs lots of sun. The more sun, the more it will produce.

If you live in an area with short growing seasons, growing kale in your garden may be an impossible task. In areas with a short growing season, you will need to start the plants indoors and transplant them outdoors as soon as you can.

It is also important that you select the right type of kale for your growing region.

For example, a coarse, ruffled, green kale developed in Italy is hardy to about 25 F degrees.

You can add variety to your garden by interplanting lambsquarters and peas with your kale.

These plants will help protect the kale from cabbage worms and other plant eating bugs.

When you grow kale, you'll get lots of nutritious leaves.

How To Plant Kale

Now that you have decided to start growing kale you are probably wondering about the best way to grow kale. Kale and other leafy greens are often grown in container gardens. However, you can also grow kale directly in the ground if you have a place to do so. The key to growing kale is healthy, happy plants. Read on to learn about growing techniques and nutrient requirements of growing kale.

Choose Your Growing Spot

When growing kale you want to pick a place that is sunny. While the plant will tolerate some shade, sunshine will give you the best production. If your garden gets full sun then you will likely be able to grow kale all year long.

Add A Light Nutrient Mix

One of the biggest mistakes that you can make when growing kale is to grow it in potting soil. Potting soil has a lot of nutrients that the plant will need in order to grow, but you don't want your kale to have a lot of nutrients. Your plant will not grow very well if you feed it too much.

Create Compost Pile

Caring For Kale Plants

Kale is an aggressive plant. Start growing kale indoors in pots about 6 weeks before your last frost date. They grow best in full sun, but can handle most any conditions just fine as long as the soil is kept well drained. It doesn’t do well in the heat of summer, so planting it in the winter will insure that you get a good head start on the growing season.

Soil pH should be somewhere between 6.4 and 7.0 to insure the highest nutrient uptake. If your soil is not in this range, you’ll want to add lime (for alkaline soil) or phosphoric acid (for acidic soil).

Soil additions can vary based on the type of bedding material you choose. Generally, 2 to 3 inches of commercial potting soil combined with either peat moss or finely ground bark will work best. The pH of the soil will allow your kale to absorb the nutrients it needs to grow strong and healthy. Incorporate 1 cup of a general purpose fertilizer into the soil along with the peat moss or bark. Add a second cup when you plant the kale.

Watering your kale periodically is enough to insure that the plants grow well. If you keep your bedding evenly moist, you’ll avoid fungal diseases like powdery mildew.

Harvesting your kale is easier than it looks.


Water, and Soil.

Kale requires very little in the way of nutrients and can grow even in poor conditions. It is a hearty plant that is indigenous to the Mediterranean and grows well in sandy, loamy, or clay soil. It will grow in either hard or soft water and is a very tolerant plant, which makes it a good choice for beginning gardeners.

However, kale will not tolerate heavy rain or standing water. If your soil is heavy, add sand to improve drainage. You must keep the soil moist at all times, but not soggy. Don’t let water remain in the leaves of the plant. Avoid overhead watering, and try to incorporate drip irrigation to keep the leaves dry.

Kale will grow in either full or partial sun, but for a full head of leaves, it needs a minimum of 6 hours of sunlight every day.


Kale comes in two varieties, curly, which tends to be more popular, and Lacinato, which has a taste similar to the white cabbage. The two varieties may look different on the outside, but the internal working is pretty much the same.

Like most leafy greens, this vegetable group is not fond of the cold, so it needs a sunny place with a steady temperature of at about 70 degrees Fahrenheit. Kale grows best in a cool climate and can suffer after hot spells.

And while we're on the subject of temperature, water is also very important. You should place the pot on a tray to collect any water that seeps out of the bottom. The surface of the soil should also be slightly damp; if it is too wet, the plant can rot, and if it is not damp enough, the roots start to dry out.

To grow kale, first place the seeds in a bowl and cover with water. Allow them to soak for a minimum of 6 hours and then place 2-3 seeds every 2 inches along the surface of a well-drained potting mixture. Place the pot on a tray with enough water to keep the surface of the soil damp. Watering involved 3 times a day; morning, afternoon, and before sunset. If you notice the leaves start to look a little dried, they need a drink.


If you’re going to get your hands dirty and grow your own food, then it’s just common sense that you have to water it. In the case of Kale, the most efficient way to water a Kale plants as it grows is to give it a deep watering only about half of the plants root systems.


The Kale plant is a heavy feeder, not surprisingly given its high nutritional value. This is not a time to be stingy with the fertilizer. It’s important to be generous to your Kale plant. A high nitrogen based fertilizer should be applied throughout the season.

At least two times a month should provide the plant with efficient amounts of nitrogen based fertilizer. And perhaps even three times a month, depending on the brand and dosage of fertilizer that you’re using.

If the leaves yellow or start to fall off, you’ll know that the Kale plant has had too much of a good thing. It needs constant monitoring especially when adding fertilizer to avoid burning the plant.


The best place for Kale is in full sun and a top soil with a balanced loamy texture. Kale does well in the acidic soil. A pH level near 6.5 is ideal. The soil should have good drainage, and should be fertile so the Kale gets all the nutrients it needs.

The best soils for Kale are loamy soils with good drainage. A pH of 6.5 is best. So, if you are buying the Kale seeds and starting from scratch, you will want to purchase the best soil you can find, as it will have the characteristics needed to grow Kale.

It is obvious that growing kale in an area with abundant rainfall is highly favored. Kale does very well in an area with natural rainfall because if the soil is already rich, and the climate is already warm, and they have the storms they need to grow, the Kale thrives and grows very well. Also, the warm moist soil in this area creates the perfect environment for the Kale to thrive.

The downside to this type of climate is there can be some diseases that thrive in warm weather. So, it is good to rotate your Kale plantings every year. This will help to eliminate problems from a single disease contaminating your Kale plantings.


One of the biggest challenges in urban gardening is finding (and affording) suitable fertilizer. Many urban gardeners prefer to use composted organic waste, because it puts waste to good use and eliminates the need for a store-bought product. Composted feces or manure also carries less risk of spreading disease. However, it is important to remember that it is important to compost any used feces or manure for at least a year, so that any potential diseases are eliminated.

In general, you should consider composted manure the same way you would consider any other wood or plant-based fertilizer. For example, if you want potatoes to grow, and you are at the sea level, you can apply a handful of steer manure or composted manure each season directly to the soil, without tilling. You can also apply manure or compost in a mound around the base of the plant, for best results. Let the compost decompose for a season before using it to fertilize your garden.

If you want herbs for example, like mint, parsley or oregano, you would want to plant those plants in beds raised 6" above the surrounding area. That means you would want to put a few inches of compost in a bed, then plant your mint or oregano.


Pruning Kale: Let's talk about pruning: this is a somewhat tedious practice. Although, it is important for keeping your kale healthy, you may find you get the "hump" when you try. Be patient with yourself and visit about growing kale with children.

Remove the central leader to encourage a bushier plant. Cut the central leader below a healthy lateral branch. The lateral branch that is now above the central leader is the new central leader. Although the central leader is now below the main branch, it will grow a new top the next year.

This is pruning; so the plant grows lower and fuller rather than taller and lankier.

PLANTING KALE: Plant in early spring in full sun or light shade. Plant in deeply tilled, fertile soil. Before planting, mix a good compost or rotted manure into the soil to give the young plants nutrients.

AFTER PLANTING: After planting, water thoroughly and mulch with grass clippings, straw or leaves to help hold in moisture and keep soil temperatures even. You'll notice a thin bluish line or ring known as the Rowel ring, encircling the leaf stalk of the plant. This ring will disappear in a few days.


Once properly cleaned and removed from the refrigerator, looseleaf varieties can be placed in a shallow tray of water to begin seedlings. To cut down on having a flat, the leaf pieces should be given space to bundle like a bouquet. To help them do this, place another piece of kale – provided it is not from the same plant – up top, and push it down along the stems.

Once the water has evaporated, move the stems into a pot or bag of moistened potting soil and use.

Seeds are sown directly into trays, flats, or pots filled with moist, sterile, well-draining potting soil at 68�-78�F. A loose, even soil moisture regime should be maintained and germination should occur within five days.

Germinate for five to seven days, or until the seedlings are 2-3 inches in height, and then remove the seedlings from the germination tray. Place the seedlings into a container of individual cells. Transplant the individual cells into a proper sized container when the plant has developed two new sets of leaves.

Space plants eight inches apart in the row with 12-14 inches between rows. Grow the plants in a soil rich in organic matter and fertilize with compost tea. Avoid using chemical fertilizers as they may burn the plant's roots.

Transplanting Kale

When Should You Transplant Your Kale?

Kale is a cold hardy vegetable that is relatively easy to grow in most environments. The only real challenges are sowing the seeds too early or transplanting them too late. Both of these situations can lead to a poor crop.

If you start your Kale seeds too soon indoors, you will have to wait a few weeks before they can be planted outside. As the Kale grows, it will become apparent that your efforts in the beginning are likely wasted. The plants will be small and wimpy.

If you start your seeds too late, it is going to take a while for the Kale to get to a large enough size to be transplanted. If your growing season starts late, the plants will likely bolt before you can get to them.

Your best bet is to start your Kale planting as early as possible and transplant it as late as possible. Just follow the tips below and you should have a bumper crop by the end of the summer.

Kale is a cool season crop. You can start your seeds outdoors, indoors, or start them indoors and then transplant them outside as little as six weeks later.

Late spring and early summer are the best times to plant Kale. If you want to take your Kale as a summer crop, make sure that you start your seeds before the middle of May.

Growing Kale Microgreens

Kale is one of the most nutritious leafy greens you can grow and it is one of the best crops for a beginner. Kale is a cool-season crop. You can grow kale year-round in the right climate zones within the U.S.

Why grow kale? Because it is nutritious and the leaves can be prepared a variety of ways.

How to grow kale:

{1}. Sow a seed every couple of days until you have at least 10.
{2}. Plant the seeds directly into the garden. The soil pH should be 6.0 to 6.8. Keep the soil moist. For maximum yield, thin plants to 12 – 18 inches apart.
{3}. Kale likes well-drained soil, enriched with compost. Keep soil pH at 6.0 to 6.8.
{4}. Kale seeds germinate in 10-20 days. Kale can be ready to be harvested before the first frost.
{5}. Radish, onion, or garlic powder can be added to enrich flavor. You can also prepare the soil by adding sulfur or cottonseed meal.
{6}. Remove the lower leaves as the plant grows. Harvest by cutting the leaves at the base.
{7}. Plant in the fall to harvest in the spring. By mid-May, kale will begin to bolt.

Good Companion Plants For Kale

Kale can be grown in almost any location where the temperature does not drop below 10 degrees Fahrenheit. It prefers a somewhat loose, well-drained soil rich in organic matter such as compost, although it tolerates clay-like soils.

Among companion plants for kale you may consider marigolds, dill, onion, garlic, basil, mint, chives, carrots, and celery as the plants best suited for growing with kale.

Dill and marigolds, for example, attract beneficial flies and wasps that in turn feed on the cabbage aphids that plague kale. Basil, chives, and onion can help repel harmful bugs. Garlic, carrots, and celery help to keep worms away.

Harvesting and Storing Kale

If you are just starting your kale plants, you may be wondering how long it takes to grow kale and how much you can expect to get from a crop.

You can typically harvest kale each week for at least eight weeks.

You can then store kale in your fridge up to one week. You can also store the kale in a plastic baggie with a few inches of water in the bag for up to two weeks.

While it may not seem like the most efficient way to store your kale, you can also freeze the leaves. To freeze kale, first chop it into smaller pieces before you blanch the leaves. Then you can store the leaves in a freezer bag.

While you can eat the kale raw, kale is edible even when frozen.

However, that does not mean you can eat the frozen kale. Because the leaves freeze slowly and gradually, there is a chance of bacterial growth. The high acid content of the leaves helps prevent bacterial growth in your kale but the frozen leaves will not be as tasty as fresh kale.

Chances are, if you are a home gardener, you will be able to consume the kale shortly after you have harvested it. It is not likely that you will have to deal with freezing and later processing.

How To Harvest Kale

Kale is a great vegetable for both beginners and experienced gardeners because it’s durable and can take a whole range of growing systems.

You can harvest the whole plant or just the mature leaves, though it’s better to harvest the entire bunch, including the stalk, for the most nutrition and flavor.

Harvest kale at the peak of the plant’s maturity out of season. The most common variety, called Green Curly, is harvested about sixty days after the seedling begins to flower.

Make sure to harvest your kale before strong winds cause it to wilt or threat of frost. These can negatively affect the vegetable’s flavor and texture.

To pick your kale, you’ll need a garden knife or scissors. Cut the plant from its stem, removing the entire stem, and let the kale fall into a basket or a bowl.

Rinse the kale and then give it a quick shake to remove any excess water.

You can enjoy kale raw, sautéed, steamed, or even frozen.

Storing Kale

Kale is an easy vegetable to grow in your backyard garden. Although it is generally available fresh in the grocery store, many people prefer to buy it fresh from the local farmer's market and harvest their own crop for use during the winter months. It is important to know the best way to store kale so that it will last from harvest until you are ready to use it. It can be stored frozen, but the flavor is not as good as when it is kept in a dark, cool place.

When is kale ready to harvest?

Kale can be harvested at any time during the growing season. Some gardeners prefer harvesting it early in the season when it is relatively small, while some choose to wait until it has grown larger and more mature. In either case, the plant should be allowed to continue to produce leaves so that you do not lose the entire harvest at once. Harvest the leaves when they are of average size and you can cut them down to size once you prepare them for storage or storage.

How to harvest kale?

When harvesting the leaves of the plant, cut close to the base of the plant with a sharp knife or garden clippers. Make sure that you remove any damaged leaves or wilting foliage. You can do this using a knife or by pinching the leaves from the individual stems.

How to store kale?

Freezing Kale

Kale is one of the most nutritious plants you can grow. It is also one of the easiest to grow. Seeds can be sown directly outside in May in zones 4 or 3 or 6. This crop can grow into the summer and keeps producing up until its first frost. Spring and fall crops can also be harvested for a third cutting. Avoid the center of the head as that is where the plant will get bitter. This crop really is great on all counts.

Kale grows fast. The leaves can be harvested as you need them. If a tough leaf sticks out just pull it out and the next leaf will grow right in its place. When the plant is cut it will develop a new leaf so you can harvest the whole plant when the center leaves are cut off. A new leaf will grow in the center of the plant. Just imagine the crop you would have if you cut off the top of your head and had 8 new heads grow back!

Any leaves that are harvested can be washed or rinsed, dried, and then baled and stored. I use an old pillow case that I have sewn closed at the top with the open end down. When I am ready to use the kale I pull it out and fluff the loose leaves and throw a tablespoon or two in my soup pot. If I do not use all of it, I can put the small ball back in the bag and it stores until I need it again.

Other Storage Methods

Because kale is so hardy, it needs little in the way of storage conditions. As long as it's not frozen, the extreme cold does not faze it. You can store whole bunches, chopped or torn kale, or kale in chopped chunks. Use it fresh or freeze it when you have a crop surplus; like other superfoods, kale can be frozen for up to a year.

Wrap chopped kale in freezer paper, then put in a plastic bag. Thaw it for use in recipes such as kale smoothies, kale chips, or cut it up to use in soups and stews.

Troubleshooting Kale Problems

Kale has been called the king of greens for its nutrient density, versatility, and health benefits. It is the powerhouse green of any vegetable garden.

If you can grow kale, you can grow anything.

So what makes kale such a superfood?

First of all, kale is not one plant; it is a variety of different plants.

The common name, kale, refers to a broad range of cabbages. Cabbages have been bred to have a wide size range, leaf shape, and colors. So, in the case of kale, you have a variety of different plants that produce a variety of different cabbages.

Kale plants have 2 types of leaves: flat or curly. The flat leaves are like a head of lettuce. The curly leaves are more like a dandelion. In the nutritional world, kale is well known for being one of the best sources of beta-carotene. Curly leaf kale is a better source for beta-carotene than leaf or head cabbage.

Kale is also very high in antioxidants and vitamin K.

The health benefits of kale are due to its dark color.

According to studies done at John Hopkins University, the darker the color, the higher the antioxidant level. This is true because of the chlorophyll.


Complaints, and Misconceptions.

One of the most common complaints against kale is that it is bitter. This is due to a number of reasons, including but not limited to:

  • burning
  • being underwatered
  • overfertilized
  • underfertilized
  • low temperatures
  • cold soil
  • weeds

While kale is a highly nutritious food- it is not highly nutritious without proper care. And it is not the only vegetable that benefits from the correct growing conditions.

For this reason, growing kale at home can be a challenge- but it doesn’t have to be.

Growing kale from seed is easy and rewarding in a number of ways. Kale is a hearty, cold-tolerant vegetable that can be grown in a variety of seasons. It can be grown indoors or outside. Kale can be grown in many different outdoor climates and has a taste and texture that improves as it becomes colder. You can plant kale in the fall and leave it out over the winter until spring.


Pests & Molds.

Mildew is one of the most common fungal diseases for kale plants and it's caused by the parasitic Botrytis Fungus. However, the most common environmental factor that causes this disease is excessive moisture. Kale plants can develop this disease when the temperature is 65 to 70 degrees Fahrenheit (18 to 21 Celsius). Furthermore, fungal thrips and silverleaf whiteflies are known to consume the leaves of the kale plants. Another fungal disease that affects the kale plant is blackheart. This disease is caused by the fungus Dothiorella. However, it is commonly found in stressed plants when the irrigation schedule is irregular.

Maintaining proper air circulation around the plants can help you control the mildew, silverleaf whitefly, and blackheart.

Since kale is not that susceptible to the whitefly infestation you should take precautions. Kale plants are susceptible to the whitefly infestation when they are young, but it can grow resistant as it ages. To keep the whitefly away, use paper bags or nylon window screen to cover the plants when they are less than a foot high. As the plant matures, the whitefly must fly upwards to get to the top of the plant, and they are unable to fly over the screen.