No-Fail Kale: The Powerful Health-Benefits of Kale and How to Grow It

"The King of Vegetables; 'Kale' to the Chief!"

Cathy, Danielle and Llyn with "bouquets" of Red Russian kale to share at the Food Pantry.

Early spring in the Pacific NW is a time of joyful anticipation of the coming growing season. We already have hundreds of seedlings started in our greenhouses and, in a few short weeks we'll be able to transplant many early-season crops outdoors. But one of the great culinary pleasures of this time of year is the kale that wintered over from last season. Kale is one of those plants that when touched by a kiss of frost, becomes more sweet and tender than when growing at the height of summer.

Eat your kale for healthy skin, hair, bones and teeth!

There are many articles on-line about the nutritional benefits of kale and recipes for its preparation.  You will not find as many articles on-line about growing kale, using it as a cover crop, or saving your own seed which is what this article is focused on. (See also our post: Kale joins the "Dirty-Dozen' list: and How to Grow Your Own Kale)

But, before we get into growing kale and saving seeds, in researching this post I discovered two important facts: Kale has the densest concentration of nutrients, per calorie, of a wide range of foods tested. (PDF of 72 tested foods) (explanation of chart).

And secondly, it is extremely important that, the source of the kale you eat is organically grown.

"The health benefits of kale greatly depend on the source you buy it from. Whenever you shop for kale, make sure to get organic kale, as it’s one of the most heavily pesticide-sprayed crops. Two-thirds of produce sampled in recent evaluations were poisoned with pesticides and non-organic kale ranks among the world’s most heavily polluted crops."(source)

How to grow it: Kale won't grow well in the tropics or arid regions but it's perfectly suited to a moist, temperate climate such as the Willamette Valley of Oregon where we live. There are several varieties available. The main two we grow are Toscana (or dinosaur) kale, with its greyish-green leaves (without many frilly edges) and mild-flavored tenderness, Toscana is perfectly suited to make roasted kale chips (recipe below).

Toscana (or dinosaur) kale

But for ease of growing and hardiness through the winter, our favorite kale is Winter Red/Russian kale. This kale actually has the nickname 'hungry gap', after the period in winter in traditional agriculture when little else can be harvested. We've had stands of it survive, outside and unsheltered through the winter - through all but the most sustained snow and cold.

Toscana kale is darker green and its leaves are less frilly (far left). Red Winter kale, hardier and more vigorous (easier to grow through the winter) is on the right.

Sign, we put with kale at the Food Pantry as many people were unfamiliar with eating it.

Typically we grow two main crops of kale per year. The first we start in early/mid-February.  We either start them in pots/six packs and transplant them outside (late March/early April) or we start them directly in beds in the greenhouse. We pick from both these plantings all the way until mid-July when a) the leaves become bigger and less tender and b) there is so much else coming ripe that we prefer to eat! In the heat of summer they often also become infested with aphids and become inedible for this reason. This is then the perfect time to sow the second crop of the season (more on this below).

We start seeds in plastic tofu-containers with holes drilled in the bottom. We fill the containers mostly full of soil and press the soil down evenly with the bottom of another container. After sowing seeds, cover with scant, even layer of soil. Keep moist but don't over-water. These seedlings above are lettuce plants (to show spacing of seeds).

Once seedlings are large enough to handle easily and they have well-developed roots, but before they are root-bound, gently dump out the batch of seedlings and tease them apart, placing one in each cell of a six-pack.

In a few weeks, seedlings will grow and their roots fill the six-pack cells. They are then ready to transplant into garden-beds (18" apart). (Red Russian kale seedlings shown)

We have also sowed the seed loosely over a whole greenhouse bed in February (ideally the seeds are about 2" apart) and cover them lightly with topsoil. The kale comes up thickly filling the whole bed and grows rapidly in the protected climate of the greenhouse. It is easy to harvest whole clumps at a time with a sharp knife or scissors and, as long as you don't cut below where the leaves generate from, the kale will keep growing back all spring until a) you want to use the bed for something else or b) the greenhouse gets too warm for the cool-loving kale and it succumbs to aphids, or mold or gets too tough to enjoy.

Here, Chris is harvesting kale that was sown directly in a greenhouse bed. Using a sharp knife, he cuts off whole handfuls of kale leaving the node where new leaves sprout untouched for future harvests. The leaves will continue to re-grow for many, many months.

The second main crop of kale (for fall and winter eating) is sown in late July. It can be done in pots and transplanted, or loosely scattered as a thick crop (either inside or outside a greenhouse). It's counter-intuitive that you start these 'winter crops' in the peak of the summer heat but the seeds need enough time to germinate, and the leaves need long enough days to gain some height and volume as they will not gain much in size once the day-length shortens after autumn-equinox (Sept. 21 or so). We usually find it challenging to have enough room in our greenhouses at the peak of summer to grow a large kale crop indoors but, since kale does well outside, except in all but the harshest winters, we've had good luck with growing it outside.

Kale as a cover-crop: Below are some pictures of an experiment we did one year with kale as a cover crop. We sowed it thickly along with fava beans (tried to space plants about 2" apart). This was done by scattering the two varieties of seed and very lightly tilling them in with tiller at shallowest depth-setting. The kale did very well and lasted all through the winter. The fava beans succumbed to a sustained hard-frost and didn't survive till spring. After eating kale all winter-long, we tilled the rest in as a source for 'green manure'. This worked fine but we are now moving away from using the roto-tiller in the spring as it really compacts our clay-dense soil but, if you're still tilling in cover-crops and have a lot of kale-seed, it's a great way to go!

Kale and fava beans as a cover crop (planted in Sept., pictured in late October). Kale survived the winter; favas did not (froze). We ate kale all winter and tilled the kale into the soil in the spring as a 'green manure' (for fertility).

The same field of kale in February. OSU students harvesting a tub-full to take home and enjoy!

Springtime bonus: Kale 'raab'
Though there are some annual varieties of kale, most are biennial and set seed in their second season, after wintering over. If you have some kale that has survived the winter, look for the start of flowers forming. The best time to catch them is before the flowers begin to open (below). These kale flowers, called 'raab' (pronounced 'rob') are very tender and have a slight 'sweet' taste. They are loaded with vitamins and minerals.

Kale 'raab' (pronounced 'rob') is the flowers of the plant before they fully open. Tender, sweet and densely nutritious; a springtime treat! (pictured: Red Russian kale-raab) Note: Pick some leaves and stems along with the flowers; they'll still be tender at this time of year.

Here's Llyn picking raab off a Toscana kale plant in March or April.

Bella loves kale, raw from the garden! We prefer to steam it for about 7-min. and eat it with apple-cider vinegar or a splash of lemon-juice.

Delicious and nutritious, spring "greens": Toscana and Red Russian kale flanked by "Red Sails" lettuce.

Kale is easy to prepare and eat. We mainly use it steamed with a little apple-cider vinegar or lemon juice sprinkled on top, or a little butter but it it also good in smoothies (recipes), fresh in a tossed salad (recipe) or baked into chips (recipe). There are many great recipes on line. Always rinse well before using.

In the spring, when plants are small, the ribs will be tender and can be chopped right in with the rest of the leaves. As the plants mature, the ribs become more woody so best to slice them out and compost them.

Kale is incredibly nutritious. A 3.5 oz. serving (100g) gives you 7% of an adult's protein needs for the day as well as 5%- 15% of several vitamins and minerals. It is also very high in fiber.

(LINK: Health Benefits of Kale)

This 'ANDI' chart (below) lists 72 foods, rating them by their concentration of nutrients per calorie. Kale is #1! They're not suggesting that you rule out the foods that are higher in calories and less dense in nutrients (healthy bodies need high-quality fats, carbohydrates and protein) but most of us are deficient in the micro-nutrients (vitamins, minerals etc) and fiber, that are essential for all our metabolic processes and optimal health. (LINK: Aggregate Nutritional Density Index - note, kale is #1) (LINK to one-page, printable ANDI chart).

'Rob' with kale 'raab'

Here's another post we wrote about the health benefits of Kale:

Kale joins the "Dirty-Dozen' list: and How to Grow Your Own Kale