Planting Winter Brassicas: Kale, Sprouts and Winter Cabbage

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Winter brassicas. Now we’re getting into the serious stuff. The stuff that separates the casual summer gardeners from the proper year-round growers. Because anyone can grow a courgette in July — the conditions are perfect and the plant basically grows itself. But growing kale, Brussels sprouts, and winter cabbage that’ll feed you through December, January, and February? That takes a bit of forward planning and some proper commitment. And it’s absolutely worth it.

There’s something deeply satisfying about walking up to the allotment in January — frost on the ground, breath visible in the air, Daisy looking at me like I’m absolutely mental for leaving the warm house — and coming home with a carrier bag full of fresh, home-grown greens. Kale, sprouts, savoy cabbage, purple sprouting broccoli. All from plants you put in months ago that have just been quietly getting on with it through autumn and winter while you’ve been sat inside watching telly and eating biscuits. Low effort, high reward. My kind of gardening.

Now I covered early brassicas in a previous post, but winter brassicas are a different beast. They’re slower growing, tougher, hardier, and many of them actually improve in flavour after a frost. Brussels sprouts are the classic example — the cold converts their starches to sugars, making them sweeter. Same with kale. If someone says they don’t like sprouts, there’s a decent chance they’ve only ever had the sad, overcooked, bitter ones from the supermarket. Home-grown sprouts, picked fresh after a frost and cooked properly? Completely different vegetable. Life-changingly good.

The Winter Brassica Lineup

Kale — the king of winter greens. Cavolo nero (black kale), curly kale, red Russian kale — they’re all incredibly hardy, productive, and nutritious. I grow cavolo nero because it looks dramatic and makes me feel like a proper Italian market gardener (I am from Sunderland, but a man can dream). You harvest the lower leaves and the plant keeps producing from the top. One plant can keep going for months. Absolute champion.

Brussels sprouts — the Marmite of the vegetable world. People either love them or hate them, and I think the haters have just never had a good one. Growing your own is the only way to experience what sprouts should actually taste like. They take a long time though — sow in March or April, plant out in May or June, and they’re not ready until November at the earliest. That’s about eight months of growing. Patience is required. But the payoff is spectacular.

Winter cabbage — savoy types are the toughest. Their crinkly leaves handle frost beautifully and they stand in the ground for weeks waiting to be cut. January King is another brilliant variety — gorgeous red-purple outer leaves and a solid, sweet heart. One cabbage is a lot of food. I grew six last year and we were eating cabbage into March. Possibly a bit too much cabbage, but that’s a quality problem.

Purple sprouting broccoli — this is the real prize of winter growing. Sow in spring, plant out in summer, wait all the way through autumn and winter, and then in February or March it erupts with these gorgeous purple shoots. It’s like the garden’s way of saying “spring is coming.” Incredibly delicious, lightly steamed with butter. The wait is tortuous but the reward is immense.

Planting Out

Winter brassicas follow the same rules as early brassicas for planting out (I covered this in detail before), but here’s a quick recap because repetition is how we learn. Ask any teacher. Or ask JB, who tells me the same things every year and I still don’t listen.

Firm soil — brassicas like firm ground, not freshly dug loose soil. Prep the bed a few weeks ahead, add compost, and let it settle. Tread it down gently with your boots. Deep planting — set them in up to their first true leaves and firm around the base really well. Press hard with your knuckles. Give them a tug to make sure they’re solid. If they rock in the wind, they won’t form properly.

Spacing is important for winter brassicas because they get big. Brussels sprouts need about 75cm between plants. Kale about 45-60cm. Winter cabbage 45cm. Purple sprouting broccoli a good 60cm. Don’t be tempted to squeeze them in. I know space is precious, but overcrowded brassicas don’t produce well and they’re more prone to disease because of reduced air circulation.

Protection from the Usual Suspects

Net them. Straight away. The second they go in the ground, get the netting on. Pigeons and caterpillars don’t care what season it is — they’ll eat winter brassicas just as enthusiastically as summer ones. I keep my brassica netting up from planting day right through to harvest. It’s a pain to work around, but the alternative is watching your entire winter food supply get demolished by birds.

Staking is worth considering for Brussels sprouts and purple sprouting broccoli, especially on exposed sites. These plants get tall and top-heavy, and winter winds can rock them loose or even blow them over. A stout cane or stake per plant, with a tie about two-thirds of the way up, keeps them upright. I lost three sprout plants in a December gale one year because I hadn’t staked them. Found them lying flat the next morning. Some of the sprouts had been knocked off. The pigeons were having a field day. Devastating.

Feeding and Care Through the Season

Winter brassicas are hungry plants and they’re in the ground for a long time, so feeding is important. Give them a good liquid feed every two to three weeks through summer and early autumn while they’re actively growing. I use liquid seaweed — it’s gentle and organic. Audrey’s legendary stinky nettle tea works brilliantly too. Once growth slows in late autumn, you can stop feeding. They don’t need it when they’re barely growing.

Keep weeding around them. Weeds compete for nutrients and water, and brassicas need all the resources they can get to build up before winter. A good mulch around the base helps suppress weeds and retains moisture. Just keep the mulch a couple of inches from the stem to avoid rot.

Water regularly in dry spells, especially right after planting and through summer. Once autumn arrives and the rain usually picks up, you can generally rely on rainfall. But keep an eye on things — a dry autumn can catch you out. My rule is: if I’m thirsty at the allotment, so are the plants. So I drink my tea and then do the watering. Priorities.

Harvesting Winter Brassicas

Kale — pick the lower leaves first, working upwards. Leave the growing point at the top intact and it’ll keep producing. You can start harvesting once the leaves are a decent size — about hand-length. Regular picking encourages more growth. I harvest kale every week or two from October right through to March.

Brussels sprouts — harvest from the bottom upwards. The lower sprouts mature first. Snap or cut them off when they’re about the size of a walnut and nice and tight. Leave the upper ones to mature. Once you reach the top, you can eat the leafy top too — it tastes like a mini cabbage. Don’t waste it.

Winter cabbage — cut when the head is firm and solid. Use a sharp knife to cut just below the head. Like early cabbages, if you cut a cross in the stalk, it might produce some secondary smaller heads. Won’t always work but worth trying.

Purple sprouting — wait for the spears to form in late winter or early spring. Pick when they’re about 15cm long and the buds are still tight. If the buds start opening into yellow flowers, you’ve left it too late for that spear (but the flowers are edible too — they taste nice in a salad). Pick regularly and the plant keeps producing for weeks.

Look after yourselves. Take good care. 🌱