Fertilising guide

How to fertilise 'Cavolo Nero' Kale (Brassica oleracea var. palmifolia 'Nero di Toscana')— schedule & NPK

Also called Lacinato kale, Tuscan kale, Dinosaur kale, Black kale.

More about 'cavolo nero' kale

About 'Cavolo Nero' Kale

Brassica oleracea var. palmifolia 'Nero di Toscana' · also called Lacinato kale, Tuscan kale · edible

Cavolo nero is the Tuscan 'black' kale prized for its long, strappy, blue-black blistered leaves and deep, sweet flavour after frost. Exceptionally hardy and easy, it crops over a long cool season from late summer into winter. Grow in full sun and firm, fertile soil, picking leaves from the bottom up so the plant keeps producing for months.

Growth habit: Upright, columnar, non-heading kale forming a tall central stem topped with a rosette of long, narrow, heavily savoyed leaves; develops a palm-like 'tree' silhouette as lower leaves are picked.

What fertiliser 'cavolo nero' kale actually wants — and why

'Cavolo Nero' Kale is grown entirely for its leaves, so nitrogen is the priority — steady, nitrogen-leaning feeding keeps it growing fast, tender and unbolted.

For the language behind the three numbers on the bottle — what nitrogen, phosphorus and potassium each do — see the NPK ratio explained entry. The short version for 'cavolo nero' kale: match the feed to the job the plant is doing right now, not to a generic “plant food” on the shelf.

How often to feed 'cavolo nero' kale, and which months

Feeding only earns its keep while the plant is in active growth and can use the nutrients — pour feed into a dormant or low-light plant and it simply builds up as root-burning salt. For 'cavolo nero' kale:

Feed for leaf production. Incorporate a balanced fertiliser before planting and side-dress every 4-6 weeks during active growth with a nitrogen-rich feed to keep leaves tender and well-coloured. Avoid over-feeding late in winter. In practice: a balanced or compost-rich start, then a nitrogen side-dress or liquid feed every 3-4 weeks through the cropping period in the main season (spring through early autumn).

The dormant-season rule matters more than the exact interval: skip feeding entirely when 'cavolo nero' kale is resting. For the wider context on indoor feeding rhythms across the seasons, the houseplant fertiliser schedule walks through the year month by month.

What strength to mix for 'cavolo nero' kale

Use the vegetable-feed label rate for 'cavolo nero' kale. Steady availability matters more than a strong dose — a check in growth makes leaves tough and can trigger bolting.

Feeding always goes onto already-damp soil, never dry roots — water 'cavolo nero' kale first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the 'cavolo nero' kale watering schedule.

Signs you are over-feeding 'cavolo nero' kale

Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for 'cavolo nero' kale:

Very soft, floppy, dark-green growth that attracts aphids.
Excess leafy growth at the expense of hearts/heads in cabbage and the like.
Salt crust and scorched leaf edges in containers; nitrate-heavy leaves.

Signs you are under-feeding 'cavolo nero' kale

Pale, yellow-green leaves, oldest first, and slow growth.
Small, tough, bitter leaves and premature bolting.
Weak, stunted heads in cabbage, broccoli and cauliflower.

If the symptoms point at watering, light or roots rather than nutrition, the full 'cavolo nero' kale care brief covers soil, humidity and the common problems for this species.

Flushing and leaching the salts

For container-grown 'cavolo nero' kale, water until it drains freely each time and flush pots monthly with plain water to stop nitrogen salts accumulating; in the ground, good compost levels naturally buffer this.

Organic vs synthetic feeds for 'cavolo nero' kale

Organic options

Well-rotted manure or compost dug in, plus nitrogen-rich liquid feeds like diluted chicken-manure pellets or nettle feed. UK: pelleted chicken manure or Westland; US: Espoma Garden-tone or blood meal. Steady and soil-building.

Synthetic / liquid feeds

A balanced feed at planting then a high-nitrogen liquid or granular side-dress — UK: Growmore then a nitrogen feed or Phostrogen; US: a 10-10-10 then a high-N (e.g. 21-0-0) side-dress or Miracle-Gro.

Brand names are examples, not endorsements, and UK and US ranges differ — check the label’s own NPK and dilution rate, since formulations change.

Fertilising 'cavolo nero' kale — frequently asked questions

What fertiliser does 'cavolo nero' kale need?

A nitrogen-leaning feed (higher first number) or compost-rich soil — nitrogen drives the fast, tender leafy growth this crop is grown for. Phosphorus and potassium matter far less here than for fruiting crops. 'Cavolo Nero' Kale is grown entirely for its leaves, so nitrogen is the priority — steady, nitrogen-leaning feeding keeps it growing fast, tender and unbolted.

How often should I feed 'cavolo nero' kale?

Feed for leaf production. Incorporate a balanced fertiliser before planting and side-dress every 4-6 weeks during active growth with a nitrogen-rich feed to keep leaves tender and well-coloured. Avoid over-feeding late in winter. Feed for leaf production. Incorporate a balanced fertiliser before planting and side-dress every 4-6 weeks during active growth with a nitrogen-rich feed to keep leaves tender and well-coloured. Avoid over-feeding late in winter. In practice: a balanced or compost-rich start, then a nitrogen side-dress or liquid feed every 3-4 weeks through the cropping period in the main season (spring through early autumn).

What strength of feed for 'cavolo nero' kale?