Growing Purple Sprouting Broccoli

Purple sprouting broccoli is the crop that earns the patient gardener real bragging rights. You sow it in spring, watch it slowly build into a sturdy plant over summer and autumn, then leave it standing through the worst of a British winter. Its reward comes in late winter and early spring, when it produces wave after wave of slim, purple, tender-stemmed spears — exactly when the veg patch is otherwise bare. If you can spare the ground, it is one of the most worthwhile things you can grow.

Why it is worth the long wait

Most vegetables crop in the same warm months, and then the kitchen garden falls quiet from January to March — the period growers call the "hungry gap". Purple sprouting broccoli is built to fill exactly that gap. While almost nothing else is ready, it hands you fresh, home-grown greens week after week, with a flavour far sweeter than anything in the shops.

It also shrugs off the cold. A hard frost actually improves the flavour, and a well-grown plant will stand through snow and keep going. Alongside kale, it is one of the few crops that genuinely earns its keep in the depths of a UK winter, which is why allotments are full of it.

The catch is time and space. Purple sprouting broccoli occupies its patch of ground for the best part of a year, so it is not a crop for an impatient first season or a tiny plot. But if you have room and a little patience, the payoff is huge. For the full picture of the broccoli family — including faster-cropping calabrese — see the main broccoli guide.

Sowing and the long season

The simplest approach is to sow in a seedbed or in modules from April to June, then transplant the young plants to their final positions in July or August. Sowing in pots or modules rather than straight into the ground makes it easy to protect the seedlings and to move them on when the spring crops they follow are cleared.

Sow the seeds about 1cm deep. They germinate readily in spring warmth, usually within a week or two. Once the seedlings have a few true leaves and are roughly 10–15cm tall, they are ready to move to their cropping site. Water them well the day before and the day after transplanting to settle them in.

Because the plants do not crop until the following late winter, there is no rush in the early stages. Use the planting calendar to line up your sowing and planting-out windows, and remember that a purple sprouting plant will hold its ground long after the courgettes and beans have been pulled out.

Where and how to grow

Like all members of the cabbage family, purple sprouting broccoli is a brassica, and brassicas have three firm preferences: firm soil, plenty of sun, and protection from pigeons and caterpillars. Get those right and the rest is easy.

Firm, fertile soil. Brassicas hate loose, fluffy ground — they want their roots anchored so the tall plants do not rock in winter winds. Choose a spot that was well manured for a previous crop rather than freshly dug and fluffed up, and tread the soil firm before planting. If your soil is thin or sandy, work in some garden compost first; our notes on improving your soil cover this. A handful of general fertiliser before planting helps the plants build the bulk they need to overwinter.

Staking. This is the step beginners most often skip, and they regret it. A mature purple sprouting plant can reach 90cm or more and carries a heavy head of foliage all winter. Push a sturdy cane or stake in beside each plant in autumn and tie it loosely, so winter gales and waterlogged ground do not topple it. A plant blown flat in January rarely crops well in March.

Netting. Cover the plants with fine insect-proof mesh or netting from the moment they go out. This keeps cabbage white butterflies from laying eggs in summer and stops hungry wood pigeons stripping the leaves in winter — pigeons can demolish an unprotected plant in a single cold week. If caterpillars do appear, our guide to cabbage white caterpillars explains how to deal with them.

Overwintering

Once the plants are established and netted, they largely look after themselves through autumn and winter. Your job is mainly to keep them upright and safe from birds.

Check the ties and stakes after every big storm, and firm any soil that frost has lifted around the base of the plants — a loosened root is a wobbly plant. In exposed gardens, drawing soil up around the stems gives extra anchorage. Remove any yellowing lower leaves now and then to keep things tidy and reduce hiding places for slugs.

You should not need to feed or water much over winter; growth almost stops in the cold and rainfall does the watering for you. The plants simply sit and wait. Then, as the days lengthen in late winter, they wake up and start to throw up the flower shoots — the spears — that you have been waiting nearly a year for.

Harvesting spears to keep them coming

Start picking when the central spear is well formed but the little flower buds are still tightly closed and green-to-purple — never wait until they open into yellow flowers, as the texture coarsens and the plant's energy goes into seeding instead of cropping.

Snap or cut the central spear first, taking about 15cm with a few leaves attached. Removing this main spear is the key trick: it signals the plant to send out a flush of smaller side spears from lower down. Keep picking those every few days and the plant responds by producing more, often cropping steadily for six weeks or more from a single plant.

The spears are best eaten fresh, lightly steamed for just a couple of minutes so they keep their colour and bite. They do not store for long, but a good row in full production will keep a household in greens right through the hungry gap.

When you are ready to expand your winter veg patch, pair purple sprouting with other hardy croppers — kale is the obvious partner — and head back to the broccoli guide for varieties and the wider cabbage family. For the full range of hardy crops worth a winter bed, browse the grow vegetables hub.