How to Grow Kale

Botanical Name:  Brassica oleracea

Plant Type: Hardy biennial

Kale may have been one of the first cultivated brassicas. Early Greek and Roman literature referred to kale-like plants.

Containing one of the highest levels of immune-boosting antioxidants, kale is more tolerant of drought and heat than other brassicas.

Tuscan black Kale is the most elegant of the cabbage family looking like a miniature palm tree with quilted elephant grey leaves. It is the easiest and most heat tolerant of the brassicas to grow. Grown mainly in Northern Europe where it is harvested even when the ground is covered in snow, it is gaining popularity in Australian gardens. As a close relative if the wild cabbage, it does not require rich soils.

Pick the young leaves from the ‘top’ of the tree as these are the most tender and just used like cabbage. They are also excellent with olive oil and shallots.

Varieties

Tuscan Black is a highly valued kale for making rolls, where the leaf is used (like cabbage) as a striking black coloured wrap. ‘Cavallo Nero’ in Italian markets is also popular and gram for gram it supplies twice the levels of antioxidants of broccoli.

Kale ‘Scarlet’ is extraordinarily beautiful with its deep purple colour and the flavour is also great. ‘Dwarf Blue Scotch’ stands up to the heat and ‘Red Russian’ is excellent in the cold.

Cultivation

Plant your seedlings in spring to ensure a year’s supply of leaves before the flower shoots (used like broccoli) appear next spring. Kale does best in full sun but does tolerate partial shade. Soil needs to be free draining and enriched with compost and aged manures for tender leaves.

Water kale plants regularly and mulch with lucerne, hay or pea straw. Feed regularly with a liquid organic fertiliser.

Sun: Full Sun

Pollination: Insect, cross-pollination

Soil:  kale prefers a well-drained soil, rich in organic matter- compost and aged manures are great additions to the soil for any leafy greens. Its pH range is a little towards the acidic side with a preference for a pH of 5.5 – 6.5.

Growing from Seed

Sow: in punnets, raise as seedlings for transplanting.

Ease of Germination: Easy

Germination Temperature: 7-23°C

Germination Time: 1-2 weeks

Spacing: 50cm

Harvest: 50-160 days

Yield: 2.6kg/m

Maintenance and Additional Care

Since kale is a leafy green, it needs soil rich in nitrogen to thrive. A green manure crop planted and dug in before planting kale is ideal. Aged manures, compost and blood and bone are perfect soil additions, but make sure you don’t overdo them – little and often is the way to go. Liquid feeds of fish emulsion and seaweed extracts during the growing season will provide food and moisture.

Although kale is a winter vegetable and drying out is not such a problem, always ensure that the plants don’t dry out. Mulching around plants will help retain moisture.

Companion Planting

Good companions: Beans, beetroot, capsicum, celery, chamomile, chilli, coriander, cucumber, dill, geranium, hyssop, marigold, mint, nasturtium, onion, oregano, potato, rhubarb, rosemary, sage, silverbeet, spinach, tansy, thyme, wormwood.

Bad companions: Garlic, grapes, strawberry, mustard, members of the nightshade family (tomato, chili, capsicum, eggplant).

Pests and Diseases

Snails and slugs enjoy munching on kale and aphids will often infest plants that are weak and vulnerable. They will also need protection from white cabbage moth.

The best way to deal with many pests is to prevent them by crop rotation, keeping the soil healthy and encouraging predatory insects into the garden by including flowering plants.

Growing in Containers

Kale can be easily grown in pots and containers. Use a premium potting mix for vegetables and water regularly. A wicking bed or self-watering pot would also be ideal to maintain consistent moisture in your potting medium.  Grow in full sun and space plants accordingly as the leaves grow.

Harvesting

Kale is a biennial, so you can harvest it in winter, and you will also see a late spurt of growth in spring before the plant goes to seed.

Young kale leaves can be harvested quite early on. However, when the plant ages, it will produce a larger batch of older leaves that you can harvest from the outside of the plant. Pluck individual leaves and avoid cutting developing buds at the centre of the plant.

Kale is a pick-and-come-again vegetable, and regular picking ensures a long cropping period

Seed Saving

Seed longevity: 4 years

Isolation Distance: 800m

How To Save Seed: All members of the Brassica oleracea will readily cross-pollinate, so if saving seed, isolation distances are vital. Biennials, seed will set in the second year, ripening from the base of the flower upward. Don’t be tempted to harvest too early – while you may lose some of the earliest seed, it needs to brown off before harvesting. Harvest the entire plant and hang upside down over a large tub to capture the seed as it ripens and dries. Once dry, using gloves, rub the stems from bottom to top (as if warming your hands) and sieve the contents. The seed will readily separate from the chaff.  Store in a cool, dry location.  

Tips and Tricks for Success

• the flavour of kale is improved by frosty conditions
• mulching will help keep the leaves of splashing soil for a clean harvest.