Kale are classified as brassica vegetables (cole crops) and belong to the mustard family of plants. These Brassicaceae plants were formerly classified as cruciferous plants.  ‘Cruciferous’ because the petals of the flowers of these crops form a cross. 

Brassica vegetables include cabbage, broccoli, cauliflower, kale, kohlrabi, Brussels sprouts, radish, turnip, rutabaga, Chinese cabbage, mustard greens and mustard cabbage (bok choi or pak choi). Since all of these plants share a recent common ancestor, they all have very similar growing recommendations and problems.

While they are quite similar, there are some key differences to ensure best success so we've broken these into separate articles for easier instruction.

Kale is high in vitamins A, C and K, folate, riboflavin and fibre. Check here for detailed information from the USDA National Nutrient Database for Standard Reference. Harvard School of Public Health recommends eating them no more than once a week.

The Canadian Food Guide recommends that roughly half of the food on your plate should be fruits and vegetables.

Kale grows to maturity between 48 to 60 days. They can be direct seeded and may also be grown as transplants for an earlier start in the garden. Transplants can be grown in your own home or purchased from a local greenhouse.

Starting your own kale plants from seed

• Start transplants about 5 - 6 weeks prior to transplanting out. You can transplant seedlings as soon as daytime temperatures reach 10°C and night temperatures are not below -2°C for several nights in a row. In Saskatoon, your plant out date is around May 13 so you can start your transplants around the first week of April.
• Sow seeds 0.5 cm deep in a commercial soilless media containing peat moss or coir, perlite and vermiculite.  Soilless media provides a disease-free environment as well as excellent drainage to minimize root disease problems. Seed 2 - 3 seeds per pot and then thin to the strongest plant after they have grown their first set of true leaves. 
• Use flats, pots or containers with bottom drainage holes. At a soil or media temperature of 24°C, brassica seeds will germinate in 5 or 6 days.
  
• Good lighting is crucial for the growth of healthy seedlings. Brassica seedling transplants require a minimum of 14 hours of light each day.
  
• Leave a fan blowing on your young seedlings as they grow to will help to grow heartier plants and to reduce some seedling diseases. Research has shown that stem diameter can be increased and height controlled by providing seedlings with constant air movement from an oscillating fan – or by lightly brushing seedling tops with a tea towel or stick at least 20 times daily.
• For more details, check out our article on growing your own transplants.

The ideal brassica transplant:

• is approximately 10-15 cm tall.
• is dark green in color, though the lowest leaves may be a lighter color.
• has a good root system but is not root-bound (tight, hard ball of roots that do not break apart when gently massaged). 
• is strong and sturdy. Transplants that are too tall will tend to break and dry out more easily once planted out into the garden. 

Fertilizing recently planted seeds or young seedlings is not recommended. The first leaves that grow are not true leaves. They are "seed leaves" called cotyledons and are shaped like a capital B. All leaves that grow after these are true leaves. Once your seedling is mature enough to grow true leaves, you can begin to fertilize two times per week using 20-20-20 water-soluble fertilizer. Mix according to label directions.

Harden off transplants prior to planting out by moving them outdoors into a sheltered, frost-free location at least 3 days prior to transplanting.

Don't forget to label what you planted. It's also helpful to draw a map to help you track planting locations and success each year. This information is critical if you're rotating your crops to help prevent insect and disease issues.

Brassicas tend to attract kale moths and flea beetles. If you're planning to stay pesticide-free, it's important to use row covers to prevent insect damage. This is especially critical if you're located near canola fields. Row covers should be installed very soon after planting, long before the insects arrive.

If you have had cutworm problems in your garden, place a collar around your transplants right after planting. Make collars out of toilet paper rolls, or any tin can or plastic container such as a yogurt container with both ends removed. Insert the collar at least 5 cm in the ground to prevent cutworms from feeding on the stems of your transplants.

Timing

• Kale may be direct seeded in the garden or planted as transplants. See our transplants tab for tips on growing or purchasing your own transplants.
• If direct seeding, try Succession planting as kale only needs between 38 to 55 days to maturity. Since kale is best harvested young, you can get several crops of kale in one growing season.
• Check your seed package for planting depth and spacing. For most kale types, plant seeds 1 cm (½") deep and 3 cm (about 1") apart in rows 30 cm (12") apart. Thin to about 15 cm (6") spacings. 
• You can transplant kale seedlings as soon as daytime temperatures reach 10°C and night temperatures are not below -2°C for several nights in a row. In Saskatoon, your plant out date is usually any time after May 13. If temperatures are too cold, kale may bolt (send up a flower stalk).
• Transplants must be hardened off before transplanting outdoors. While mature brassicas are frost tolerant, young transplants are less so.
  

Planting instructions

• When planting, cover the entire transplant “plug” or seed ball with soil to prevent the plant from drying out.  Exposed peat or coir within the plug will act as a wick, drawing water away from the transplant and drying out the root ball.
• Gently massage the roots within the plug so that the roots will grow into the surrounding soil and not remain restricted within the ball.
• Kale transplants should be spaced 15 cm apart within the row, allowing 30 cm between rows.

•  Black Magic, Dazzling Blue, Red Russian, Vates, White Russian, Winterbor

The following cultivars are recommendations from the University of Saskatchewan vegetable program field trials, which were conducted from 1989 through 2016. Although this information is no longer current, some may find it useful.

• Blue Armor, Blue Ridge, Blue Curled Scotch, Blue Knight, Blue Vates, Squire, Starbor, Winterbor

• Actively growing kale plants prefer 2.5cm moisture/week in well-drained soils.
• Kale can be grown successfully most years without additional water though you can expect smaller plants as a result. Water will affect yields, so if you're using more intensive growing methods you will need to water.
• Pick weeds as they appear, especially those in the Brassicaceae family which attract the same insects: common pepper-grass, shepherd's purse, stinkweed, Argentine canola, ball mustard, dog mustard, flixweed, Polish canola, wild mustard and wild radish. 
• To reduce weeding, apply a thick layer of mulch around your kale plants.

Kale is not suited to fall seeding.

Kale is best grown as transplants in the far north if large plants are desired. They can also be direct seeded if harvesting younger tender leaves.

See our preservation section for more videos.

Any variety of kale works well in containers.

Kale are biennials and set seed in their second year of growth when grown in a warmer climate. Since they do not survive a prairie winter, seed saving is not recommended. 

As our climate continues to change, this may become a viable option for prairie gardeners in the future.

Loosen the soil around the kale with a fork (take care not to bruise or damage it) and pull the entire plant from the ground. Remove the leaves.

For ongoing harvest, remove a few outer leaves from each plant, leaving several leaves in the centre. Kale will continue to grow more leaves from the centre.

Kale doesn't have a particularly high respiration rate. While it is important to keep them cool during harvest, as it is with most vegetables, it isn't critical.

Kale can be steamed, boiled or sauteed as a side dish or added to stir fry, soups, stews or casseroles. 

Kale can be dehyrdated and made into chips. 

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