Kale: origin, leaves, flowers & benefits


With a passion for growing installed at an early age, I have always been happiest outdoors in nature. After training as a professional gardener and horticultural therapist, I currently run horticultural therapy and community kitchen gardens in the UK, helping others access the many physical and mental health benefits of growing vegetables, fruit and plants.

Favourite fruit: apples and pears
Favourite vegetable: asparagus

Kale is not only delicious but is also often grown as an ornamental. Discover more about kale including its origins and benefits.

Basket full of fresh kale
Kale is not only highly nutritious but tasty as well [Photo: Alice-D/ Shutterstock.com]

With its superfood status, kale (Brassica oleracea Acephala Group) is known for its healthy and high nutritional content. However, the brassica kale is not just super healthy but also attractive in its own right. Loved for its edible and ornamental foliage, find out all there is to know about kale and its properties and uses.

Kale: origins and properties

Considered a descendant of the wild cabbage, kale has been cultivated for thousands of years. Originating from southeast Europe and western parts of Asia, kale is now a popular choice both to buy and grow here in the United Kingdom. Although usually grown as an annual, kale is in fact a biennial and there are even some perennial kale varieties to grow. Kale is grown for its leaves, which are generally curly and green or red. However, you can also grow some striking cultivars that are blue green with pink veins or those with long sword-like leaves. When cooked, kale tastes slightly nutty and earthy, but you can also use kale raw. As a biennial, kale produces small four-petalled yellow flowers in its second season, which are loved by pollinators. You can eat the kale flowers or allow them to go to seed to collect for further kale sowings. Kale plants vary hugely in size, depending on the variety. Dwarf cultivars tend to grow to no more than 30 to 40cm, whereas taller varieties such as ‘Nero di Toscana’ can grow to more than 1.2m high.

Small kale plants in soil
As a cool weather crop, kale is well suited to our climate [Photo: FootMade0525/ Shutterstock.com]

Plant care

Whether sown undercover or directly in the bed, kale prefers a fertile and free-draining soil and to be grown in full sun. To encourage its leafy growth, water kale regularly from transplanting onwards until it is fully established. Once fully grown, rainfall is often enough, and watering is generally only required during hot and dry periods. As a top-heavy plant, all but the smallest varieties need to be supported or staked to prevent them from falling over, especially on an exposed site. Discover more tips on growing and planting kale in our separate article.

Common kale pests and diseases

As a hardy and tough vegetable, kale tends to grow without issue. However, as a brassica, kale can succumb to some of the following common pests and diseases:

  • Cabbage white butterfly (Pieris rapae):the black and yellow caterpillars of the Cabbage white butterfly are a common kale pest and can strip kale leaves bare if not protected. You can protect your kale plants by growing them under a brassica cage or fleece and with companion plants such as dill (Anethum graveolens) and sage (Salvia officinalis).
  • Cabbage white fly: the sap-sucking Cabbage white fly(Aleyrodes proletella) affects kale and other brassicas. Small infestations can be tolerated. To help deter Cabbage white fly, you can encourage natural predatory insects such as ladybirds (Coccinellidae) into the area.
  • Club root: affecting the roots of brassica plants, club root (Plasmodiophora brassicae) is a common fungal disease of kale. You can help prevent club root by growing kale cultivars with better resistance and practising crop rotation to maintain optimum soil health.
  • Slugs and snails: slugs and snails (Gastropoda) like to eat kale and can cause serious damage to young plants.Preventative controls include handpicking by torchlight, laying barriers of eggshells or sharp grit around the plants and promoting natural predators into the garden. If this fails, nematodes can be applied.
Cabbage white larvae eating kale
The caterpillars of the Cabbage white butterfly are a serious kale pest [Photo: Elena_Gr/ Shutterstock.com]

Is kale winter hardy?

As one of the toughest vegetables, kale is rated H5 for hardiness and can withstand all but the worst of winters and temperatures as low as -10 to -15 °C. Furthermore, it is said that harvesting kale after the first frost of winter improves the kale’s flavour as the bitter compounds decrease, making it sweeter.

Kale benefits and uses

Often referred to as a superfood due to its high nutritional content, there is no doubt that kale is an extremely healthy addition to your diet. High in fibre, yet low in calories, kale also contains vitamins A, B, C and K along with other minerals. Even though kale is most beneficial when eaten raw, it is most often cooked or added to winter soups and stews. Since cooking reduces the nutritional benefits of kale, you can steam or blanch kale for only a few minutes to help retain its colour and nourishing goodness.

Is kale poisonous to cats and dogs?

Although highly nutritious for humans, kale can be toxic for cats and dogs. Kale leaves naturally contain calcium oxalate and isothiocyanates, which when eaten in all but small amounts can lead to bladder and kidney complications and other gastric issues in animals.

Kale buried under the snow
Kale is hardy and able to withstand temperatures as low as -10 to -15 °C [Photo: Gert-Jan van Vliet/ Shutterstock.com]

Some of the taller kale varieties require a lot of room to grow. However, if space is at a premium, you can also grow kale in pots.

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