If you're growing directly outdoors, the steps are quite similar. You can certainly grow kale from seeds if you'd like, or perhaps utilize transplants from a farmer's market or retailer.

After your area’s last frost date, plant seeds 12-16” apart, about ¼” deep (a little deeper if needed to keep seeds moist).

Fill the space in your garden with these crops that will be ready to harvest before the end of the growing season.

If you plant kale late in the summer you can harvest it from fall until the ground freezes in winter. Plant the seeds 1/4 to 1/2 inch deep into well-drained, light soil.

A pack of kale seeds is available to buy for less than £2 online. On Amazon, a pack of Curly Kale costs just £1.85 while Kale Dwarf Green Curled Seeds are £1.95.

If you grow kale in the ground, you don’t need potting mix, just a good 3- to 4-inch mulch to protect soil moisture in summer and soil temperatures all year. Kale grows best with plenty of nitrogen.

"Seed prices are through the roof," Flaim said in an interview, adding that kale sales have jumped by more than 30 percent annually over the past few years. "The price has probably gone up 80 ...

With demand for kale surging, that's creating a major headache for some kale farmers who are having trouble finding sufficient supplies of kale seeds to keep up with demand.