If you are not growing kale on your market farm right now, you need to drop everything and go plant some. Do it. Right now. I’ll wait…
Seriously though, kale is a workhorse of a crop and is super popular. I mean people wear shirts with “Kale Yeah” on them. It’s crazy!
I have to admit that I am a bit of a kale junkie myself, I love its deep, dark, green taste and high nutritional value. And guess what? Your customers do too.
In fact, kale can make a higher net profit than the same area of outdoor tomatoes. Kale is so popular that it is getting harder and harder to find seeds from seed companies.
Not only do customers love to buy them, but they are also a great crop for a grower, as brassicas are reliable workhorses, providing large harvests over long periods.
Kale is a semi-perennial crop, meaning that leaves from a single plant can be harvested several times a season. Isn’t that awesome?!
In this article, we will be learning from a few experts on their experience growing Kale. In no particular order, they are, JM Fortier (the market gardener), Curtis Stone (The Urban Farmer), and Pam Dawling (Sustainable Market Farming).
Kale Varieties
Vates Dwarf Blue Scotch Curled is the most cold-tolerant kale type and is good for both spring and fall plantings.
Hanover is a spring variety that is pretty popular.
Nero di Toscana, or dinosaur kale, is popular but it can harbor aphids in the curled-back edges of the leaves.
White Russian and Red Russian do well in a winter hoophouse, but not particularly well outdoors, depending on your climate.
Some other varieties to consider are Winterbor, Darkibor, Redbor, and Toscana.
You might have to grow a few varieties at first to see what grows well in your climate and what your customers like.
Crop Requirements
Brassicas do best on fertile, well-drained soil with adequate moisture.
They require lots of potassium, so a sprinkling of wood ash, kelp meal, or granite dust could be helpful.
Calcium, boron, manganese, and molybdenum are also important for good brassica crops.
Healthy, biologically active soils can usually supply enough of all of these.
Optimal growing temperatures for most brassicas are 60-65°F (15-18°C).
Sowing
In early spring, transplants have the advantage over direct-seeded crops. They grow faster under protected conditions and bring earlier harvests.
At other times of the year, you may prefer to direct seed.
Work back from the desired harvest date to calculate the sowing date. You will need to allow for your climate and choose a realistic transplanting date.
For an earlier crop, start transplants eleven weeks before the last frost date, and set them out at 6-8 weeks old.
A good practice is to produce 20% more starts than you intend to grow, so you can pick the best and sail through 20% of a disaster.
Despite being a cool-weather crop, brassicas germinate very well at high temperatures. The ideal temp is 77-85°F (25-30°C), and 95°F (35°C) is still OK.
Given enough water, the seedlings will emerge in 4 ½ days at the low end of this range, and in only 3 days at the top end.
The minimum temperature for good germination is 40°F (4.5°C), but you will need to wait more than two weeks for emergence if it is that chilly.
There are several systems for growing transplants: open flats, cell packs or plug flats, and outdoor seedbeds.
People who use cell packs for brassicas often use the 48 cell inserts in a standard germination tray or the 72 cell size with 1.5” cells.
On Pam’s farm, they start most of their spring brassicas in open flats, sowing 3-4 seeds per inch.
They press a plastic ruler 0.25” deep into the seed compost to make a small furrow, spacing the rows 2-3” apart.
As soon as the leaves are fully open, they spot (prick) them out to the 4” deep flats with 40 plants per 12″ x 24” flat.
The plants grow to transplant size in these flats.
Once they have emerged, the seedlings need good light, nutrients, airflow, and protection from bugs.
A good temperature range for growth is 60-70°F (15-21°C).
For the last two weeks before transplanting, harden off the plants by moving them into cooler, breezier, brighter conditions.
Pam has also had good success sowing in a hoophouse bed and growing the young plants there to transplanting size (about 5 weeks old).
The bare root transplants adapt well to outdoor conditions.
Stressed-out plants are more likely to bolt.
Curtis Stone does only two plantings of kale per year, one in early spring (where transplants are set out the first week of April) and one in fall (where transplants are set out the first week of August).
Due to high amounts of aphids in his climate, he does not grow kale for about 6 weeks beginning in July.
Likewise, JM grows kale in spring and late summer/fall. He opts for Swiss chard during the summer months.
This is because kale grows well in cool conditions, which makes it a good spring crop as well as a great cold-hardy crop.
It can survive temps as low as 14°F (-10°C) and can stay outside until the last harvest of the year.
If you were so inclined, you could grow kale throughout the winter, as long as it is fully mature and standing at least one foot off the ground before the first major frost.
By picking the bottom leaves first, you train the plant upward, which will keep it high off the ground.
In some climates, kale can survive 6” of snow on the ground and be ready to harvest again by mid-March.
You could do a later summer planting in a greenhouse and can harvest all winter long as well.
Transplanting Kale
Aim to transplant your kale at four or five true leaves (5-8 weeks after sowing). Soil temperatures of 65-75°F (18-24°C) are ideal.
Pam and team transplant their kale every afternoon until complete.
Water the seedlings well before transplanting, and plant up to the base of the first true leaves to give the stem good support.
Press the soil very firmly around the plants so that the roots have good soil contact and won’t die in an air pocket.
Water within half an hour of planting and again on the third and seventh days, then once a week.
Pest Control
Using row covers keeps many pests off the plants while they are small.
If you have problems with aphids like Curtis, try his method and don’t grow kale when they are at their worst (July).
Pam’s kale suffers from the harlequin beetle and her team just simply handpicks them off the plants.
Harvest
Overwintered kale tends to bolt around mid-May, so should be harvested until then.
A good technique for harvesting kale is by snapping off the largest leaves.
To stay organized, use a marker flag to show which bed to harvest next, and move it to the next bed after each harvesting.
Pam harvests kale three times a week and takes the produce directly to the walk-in cooler. They should keep for over a week in the cold room.
Bottom Line
Kale is a super popular, awesome producer, and fairly low maintenance crop. You should definitely be growing it if you aren’t already!
If you have any kale growing tips you’d like to share in the comments below, please do!
Stay Local,
Kathy & Jon
your friendly neighbourhood growers
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