Why winter is the right time
Kale earns its keep precisely when the rest of the kitchen garden has given up. It stands in the field through frost and bitter wind, harvested from autumn right through to early spring, and the cold does something useful to it: as temperatures drop, the plant converts stored starch into sugar. The result is a leaf that is markedly sweeter and more rounded in flavour than anything pulled in September. Kale bought in January from a British grower is, in most years, a better vegetable than kale bought in October.
The main varieties and what sets them apart
Curly kale is what most people picture: densely ruffled, a bright blue-green, with a robust, slightly mineral flavour. It is the workhorse of the three types most commonly grown in Britain and holds up well to heat. The frilled edges crisp beautifully in a hot oven and catch dressings and cooking fats in a way that flat leaves do not.
Cavolo nero — sometimes sold as Tuscan kale or black kale — looks nothing like its curly cousin. The leaves are long, dark, almost slate-coloured, with a heavily puckered surface and a more savoury, earthy depth. It braises exceptionally well: the long, sturdy leaves soften into something silky without losing their character, making them a natural fit for slow-cooked soups and bean dishes. Raw, shredded very finely, cavolo nero has a pleasant bitterness that works well with sharp dressings.
Red and Russian kales are less common but worth seeking out. Their leaves are flatter and more tender than curly kale, with a delicate, slightly peppery flavour and attractive reddish-purple colouring that deepens in cold weather. They cook faster and are the most approachable of the three for anyone who finds curly kale a little robust.
What good kale looks like
The leaves should be firm and springy, not limp or rubbery, and the colour ought to be vivid — deep green for curly and cavolo nero, bright with any red or purple tones intact for Russian varieties. Yellowing is a sign of age; flavour goes with it. Stems should look freshly cut, not dried out at the base.
At a farmers' market or farm shop, kale is often sold as whole stalks rather than pre-stripped bags, which is preferable — the stalk protects the leaf and the whole thing keeps longer. Avoid pre-bagged kale that feels wet or compressed inside the packaging.
At home, keep it unwashed and loosely wrapped in the salad drawer. It will hold for several days, longer if the leaves are still attached to their stems. Once washed, use it promptly.
How to cook it
The stems of curly kale and cavolo nero are tougher than the leaves and need stripping before cooking. Hold the stem at the base and pull the leaf back against the grain with your other hand — it comes away cleanly. Russian kale is tender enough that its thinner stems can usually be left on.
Quick sautéing in a wide pan with a little oil and garlic suits curly kale well: high heat, not too long, the leaves just wilted and starting to catch at the edges. Cavolo nero rewards a more patient treatment — braised with stock, or added to a soup and left to cook down for twenty minutes or more, it becomes something quite different from the raw leaf. Both types crisp well in a hot oven, though curly kale's ruffled surface makes it particularly good this way, turning into something closer to a crisp than a cooked vegetable.
All three varieties take bold flavours well: garlic, chilli, anchovies, good olive oil, aged hard cheese. They are not delicate and do not need to be treated as if they were.
Why sourcing matters
Kale sold through farm shops, box schemes, or local markets is almost always grown closer to you and picked more recently than pre-washed bags that travel long distances in refrigerated lorries. With a vegetable where freshness directly affects flavour — and where the sweetening effect of cold weather is a real and specific thing — buying from a grower who harvested it within a day or two makes a noticeable difference. If you have access to a veg box scheme sourcing from British farms in winter, kale is one of the strongest arguments for using it.
