How to Grow Kale
'Nero di Toscana' from Seed
The Italian winter delicacy from a single seed packet -- dark grey-blue-green savoyed leaves on an architecturally beautiful 60-90cm plant that looks as striking in a cottage garden border as it tastes in a Tuscan ribollita; sow in modules from March; harvest baby leaves cut-and-come-again from summer; leave through the first autumn frosts as the flavour transforms from pleasant to exceptional; also grows as microgreens year-round
Kale 'Nero di Toscana' -- Cavolo Nero, Black Tuscan Kale, Dinosaur Kale, Palm Tree Kale -- is the Italian heritage vegetable that has been grown in the kitchen gardens of Tuscany since at least the 18th century and is now valued across the UK both as one of the finest winter vegetables available from seed and as a genuinely ornamental plant beautiful enough to earn its place in a formal cottage garden border. The long, narrow, deeply savoyed and puckered leaves are an extraordinary dark grey-blue-green that reads almost black in certain lights -- which is both the source of the name (nero means black in Italian) and the source of the ornamental value. A mature Nero di Toscana plant, with its cluster of long dramatic leaves crowning an upright stem from which the lower leaves have been harvested, looks more like a small ornamental palm tree than a conventional vegetable.
The flavour is the plant's most important quality. Raw, young leaves have a mild, sweet, slightly peppery note that works beautifully in salads and smoothies. But the transformative event is the first autumn frost: exposure to freezing temperatures triggers the conversion of starches to sugars within the leaf tissue, producing a sweet, rich, silky depth that makes Nero di Toscana the finest kale for autumn and winter Italian cooking -- the essential ingredient in Tuscan ribollita, Portuguese caldo verde, and countless other cold-weather dishes. Gardeners who grow this variety understand why a hard winter frost is not a disaster but a welcome event.
Quick Facts at a Glance
Plant Type
Hardy biennial vegetable H7 -- also ornamental; also as microgreens
Harvest
Young baby leaves all season; mature leaves autumn-winter; flavour sweetens after frost
Height
60-90cm mature; architecturally beautiful -- suitable for cottage garden borders
Sow
Modules March-June; plant out when 7-10cm; space 50cm; harvest bottom leaves up
Frost
Flavour improves dramatically after the first frost -- an autumn-winter delicacy
Difficulty
1 out of 5 -- reliable, low-maintenance, hardy
Understanding the Plant
The Frost Sweetening -- Why Cold is Good
The dramatic improvement in Nero di Toscana's flavour after frost is a genuine biochemical phenomenon, not culinary lore. Kale plants respond to cold temperatures (below approximately 4°C) by breaking down stored starch compounds into simple sugars -- a process called starch-to-sugar conversion. This is the plant's physiological response to prevent ice crystal formation in the leaf cells by lowering their freezing point. From the cook's perspective, the result is a transformation from the slightly bitter, somewhat tough leaf of early autumn to the sweet, silky, deeply flavoured winter green that makes the plant so highly regarded in Italian and Portuguese cuisine. Leave kale in the ground through the first frosts and harvest when needed -- the quality improves with each subsequent frost.
The Palm Tree Habit -- Harvesting for Ornamental Effect
Nero di Toscana is typically harvested by removing the lower leaves progressively as the plant grows -- starting at the base of the stem and working upward over weeks and months. As the lower leaves are removed, the central growing tip continues to produce new leaves at the top, and the bare stem becomes progressively longer. The result, by late winter on a well-established plant, is genuinely architectural: a single upright stem 60-90cm tall, topped with a dramatic crown of long, dark, dramatically savoyed leaves. In a border setting, this habit creates exactly the same "exotic architectural statement" quality as a tree fern or a banana plant -- but at a fraction of the cost and with the additional benefit of being edible.
Also as Microgreens
Nero di Toscana can also be grown as microgreens -- harvested as seedlings 5-7cm tall at 7-10 days after germination, before the first true leaves develop. The microgreens have the characteristic dark green colour of the mature plant and a concentrated version of the kale flavour -- sweet and mild. Sow thickly in a tray or pot on the surface of moist compost, keep at 18-22°C in bright conditions (light aids germination), and harvest with scissors when the seedlings are 5-7cm tall. An indoor crop year-round.
Sowing & Growing On
Sow in Modules from March -- Transplant at 7-10cm
Sow one or two seeds per module cell, 1.5cm deep, indoors or in a greenhouse from March onwards. Thin to one seedling. Keep at 15-20°C. Germination in 5-10 days. Transplant to final growing position when seedlings are 7-10cm tall, spacing 50cm apart in brassica rotation.
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Sow 1-2 seeds per module cell, 1.5cm deep, indoors from March-June. Germination in 5-10 days at 15-20°C. Thin to the strongest seedling per cell. Grow on in cool, bright conditions. Transplant to the final position when 7-10cm tall -- do not allow to become pot-bound in modules.
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Plant out in the final growing position, 50cm apart. Full sun to partial shade; moisture-retentive, reasonably fertile soil; well-drained but not dry. Firm in well and water thoroughly. Fit brassica collars around the stem bases to deter cabbage root fly. Net over young plants if cabbage white butterfly pressure is high in the area.
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Harvest baby leaves from the outer base of the plant throughout summer. Remove the lowest leaves first, taking 2-4 leaves per plant per harvest and leaving the growing tip and upper leaves to continue development. Young leaves harvested at 10-15cm are at their best raw in salads. The cut-and-come-again harvest can begin when plants are 30cm tall.
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Allow through autumn frosts for maximum winter flavour. Do not harvest all remaining leaves in autumn. Leave plants in the ground through the first frosts (typically October-November). After frost, the flavour transforms significantly -- harvest leaves as required through winter. The plant can be harvested right through to February or March.
Growing On & Care
In the Kitchen -- Italian and Portuguese Heritage
Nero di Toscana is the essential ingredient of ribollita -- the Tuscan bean and bread soup that is one of the great dishes of Italian peasant cuisine. It is equally essential in caldo verde, the Portuguese kale and potato soup. Beyond traditional dishes, the dark, silky winter leaves work brilliantly in: pasta with garlic, chilli and olive oil; stirred into white bean stew; wilted with pine nuts and raisins; or as a base for any slow-braised winter vegetable dish. Young spring and summer leaves are mild enough for raw salads and smoothies where their dark colour provides dramatic visual contrast to lighter green vegetables.
In the Ornamental Border
Nero di Toscana is one of very few vegetables ornamental enough to merit a place in a formal or cottage garden border alongside flowering plants. The dramatically dark, puckered foliage provides strong colour and textural contrast to the softer greens and mixed colours of flowering cottage garden plants. In a winter border where most plants have died back, the architectural palm-tree silhouette of a late-winter Nero di Toscana plant provides genuine structural interest that few ornamental plants can match. Plant in groups of 3-5 at 50cm intervals in the middle-to-back of a border for the most striking effect.
Brassica Rotation and Crop Protection
Nero di Toscana belongs to the Brassicaceae family and should be included in the 3-4 year brassica crop rotation to prevent the build-up of clubroot and other brassica-specific soil diseases. Do not follow kale with other brassicas (cabbage, Brussels sprouts, broccoli, cauliflower, swede) in the same ground within the rotation period. Net young transplants against cabbage white butterfly; fit brassica collars against cabbage root fly. Kale is generally more resistant to brassica pests and diseases than most other vegetables in the family -- a genuinely robust and forgiving crop.
Winter Harvest -- How and When
From November onwards, harvest Nero di Toscana as required by removing individual leaves from the lower part of the stem, working upward progressively. Each leaf removed reveals more bare stem and the ornamental palm-tree habit develops simultaneously with the harvest. Remove up to 4-5 leaves per plant per harvest, leaving the growing tip and 5-8 upper leaves to continue photosynthesising. After hard frosts the leaves may look wilted but recover fully as temperatures rise -- the frosted leaf is at peak flavour.
Nutrition
Kale is among the most nutrient-dense vegetables available from a UK garden. Nero di Toscana provides substantial quantities of vitamins K, A, and C; calcium; iron; and a range of antioxidant flavonoids and carotenoids. Calorie for calorie, kale provides more nutritional value than almost any other garden vegetable. The dark colour of Nero di Toscana -- derived from high concentrations of chlorophyll, carotenoids, and anthocyanins -- is directly correlated with its exceptional nutritional density compared to paler kale varieties.
As Microgreens
For indoor growing year-round: sow seeds thickly on the surface of moist compost in a tray or pot, 2-3mm deep. Keep at 18-22°C in bright conditions. Germination in 3-5 days. Harvest with scissors at 5-7cm height (approximately 7-10 days after germination). The microgreens have dark green cotyledon leaves and the characteristic Cavolo Nero flavour in concentrated form. Sow every 10 days for a continuous indoor harvest.
Sowing & Harvest Calendar
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| Sow modules (Mar-Jun) |
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| Plant out (May-Jul) |
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| Baby leaf harvest |
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| Frost sweetening |
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| Winter harvest |
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Common Problems & Solutions
| Problem | Likely Cause | What to Do |
|---|---|---|
| Caterpillar damage on leaves | Cabbage white butterfly | Net young transplants with fine insect-proof netting. Remove caterpillars by hand when found on established plants. Cabbage white butterfly pressure is typically highest in July-September. Kale is generally more robust against caterpillar damage than other brassicas. |
| Club root (swollen, distorted roots) | Infected soil; no rotation | Maintain a 3-4 year brassica rotation and do not grow kale in the same ground as other brassica crops within that period. Raise soil pH by adding lime if clubroot has been a problem -- clubroot is suppressed at pH above 7.0. Remove and dispose of (do not compost) affected plants. |
| Bitter flavour in autumn | Not yet frosted | Nero di Toscana's flavour does not reach its best until after the first frosts. Harvest baby leaves in summer and early autumn if preferred; wait for post-frost harvests for the sweet, silky winter flavour that makes the plant outstanding in cooked dishes. |
| Leggy plants; poor leaf production | Overcrowded; poor nutrition | Space at 50cm -- overcrowded kale produces tall, unproductive plants. Ensure the growing soil has been improved with well-rotted compost or manure before planting. Side-dress established plants with a balanced granular fertiliser in July if growth is slow. |
Plant Specifications
From Norfolk border to Tuscan ribollita -- the winter kale whose flavour the frost transforms
Sow one per module cell from March, transplant at 7-10cm into the final position at 50cm spacing. Harvest the lowest leaves cut-and-come-again from summer. Leave through the first October-November frosts without harvesting -- the cold transforms the starch to sugar and the flavour deepens dramatically. Then harvest the dark, silky leaves through to February. The frost is not the end -- it is the beginning.
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