Featured Image: Frosty purple-hued cabbage.
Hello readers!
My name is Natasha, and I’m the Garden Educator at Cheekwood. My work here involves managing a raised bed vegetable garden (the Cheekwood GROWS Garden) and leading educational programming in this space. In this monthly blog series, I explore cultivated edible plants and our relationships with them in Middle Tennessee.
You may know Brassica oleracea by many names. Collard greens, broccoli, kale, cabbage, Brussels sprouts, kohlrabi – all these vegetables are of the same species, despite how different they appear. They thrive in cool weather and will survive light frosts with no protection necessary, which makes them great choices for an early spring vegetable garden.
When found in the wild, B. oleracea is known as wild cabbage. Its original home is the Mediterranean, where it grows along coastal limestone cliffs. To survive this harsh environment, B. oleracea stores lots of water and nutrients within its thick, waxy leaves, like a succulent. In its second year of growth, it uses that nutrient storage to produce bright yellow flowers and reproduce.
The nutrient density of wild cabbage was likely attractive to the people who first chose to eat and grow the plant. Who exactly these people were is difficult to trace. What is certain is that many farmers, across regions and cultures, selectively bred B. oleracea over thousands of years to produce an extraordinary variety of vegetables. While this is not an uncommon practice in agriculture (both beets and chard come from the species Beta vulgaris), B. oleracea provides the most striking example of the power of artificial selection. From this single plant we have developed many vegetables that are cultivars (cultivated varieties) highlighting different parts of the plant:
- Collards and kale – bred by farmers for their leaves
- Broccoli and cauliflower – these are large inflorescences (the flowering parts of the plant)
- Cabbage – a massive terminal bud
- Brussels sprouts – a collection of lateral buds (this is why they look like tiny cabbages)
- Kohlrabi – a very swollen stem
Springtime curly kale.
These vegetables may be nearly genetically identical, but they are separated by cultural context. Cabbage, for example, has long been considered a subsistence crop, bred to have a long shelf life and sustain people through cold winters. Due to its high nutrient content, it was once used to prevent scurvy on long voyages at sea. As with all B. oleracea vegetables, cabbage arrived in North America along with European settler colonialism and has been a staple in regional cuisines ever since. Its popularity is tied to its affordability; in 2022, the USDA reported that cabbage was the cheapest fresh vegetable in grocery stores at about 80 cents per pound.
December harvest of collards, kale, and bok choy (a different brassica species, B. napa).
Collard greens also have a history of subsistence agriculture. Enslaved people laboring on plantations in the South relied on the food they grew in their vegetable gardens for survival. In addition to having little time or resources with which to grow this food, they were limited to growing a select few crops, collards being one of them. By braising collards with ham hocks, they brought the West African culinary tradition of stewed greens to the South and created a life-sustaining dish that remains a soul food staple to this day.
And then we have kale, relatively unknown in the United States until the 2010s, when it rocketed to stardom as a “superfood” touted by nutritionists, celebrities, and recipe bloggers alike for its many health benefits. The USDA reported that from 2007 to 2012, the number of farms growing kale increased from 1,000 to 2,500. Much of this growth happened in the South – today Georgia is second only to California in kale production.
Cross-striped caterpillars enjoying some collard greens.
But behind the expensive smoothies, salads, and grain bowls is a vegetable that, just like cabbage and collards, has historically fed rural communities. In Scotland, kale was once so widely consumed that the Scots word “kail” became synonymous with dinner. And yes, kale is a healthy vegetable with high concentrations of vitamins and protein. But other cultivars of B. oleracea don’t fall far behind in that regard. Where are all the cauliflower smoothies?
If you’re hoping to grow B. oleracea crops this spring, I recommend planting seeds outdoors as soon as your soil is workable (i.e., not frozen). Alternatively, you could start seedlings indoors in February and transplant them outdoors in March. Our cool season is short, and out of these veggies only collards are particularly heat tolerant. I like to cover brassica crops with protective netting until they are fully grown. This prevents small critters from gobbling the emerging seedlings, and protects growing plants from cabbage moths, who will lay eggs on the underside of brassica leaves that quickly turn into hungry caterpillars. Happy gardening!
Kale Pesto
All B. oleracea crops contain chemical compounds called glucosinolates, which hang out inside the plant’s cells until a pathogen, insect, or herbivore attacks. As soon as the cells are damaged, glucosinolates undergo a chemical reaction and turn into mustard oils. These pungent compounds are unpleasant and sometimes toxic to many insects that would otherwise eat brassicas.
By blending kale into a pesto, you are causing this chemical reaction to occur a million times over, all at once. Dramatic! But don’t worry – in this recipe, the acidic lemon juice and rich parmesan cheese balance out the mustard oil bitterness of the kale.
Ingredients:
- 2 cups kale, roughly chopped
- 3 cloves garlic
- 3/4 cup grated parmesan cheese
- 1 cup walnuts
- Juice of 1/2 lemon
- 2/3 cup olive oil
- Salt and pepper to taste
Instructions:
- Add all ingredients except olive oil to a food processor and blend until thoroughly combined.
- Slowly add olive oil through the chute of the food processor while continuing to blend.
- Adjust for seasoning, then serve with your favorite pasta or protein.
If you have questions, comments, or suggestions for future topics, you can contact me at [email protected].