Brussels are a stalwart among winter vegetables and a traditional festive favourite. They have the best flavour when harvested after being frosted – superior to anything you can buy in the supermarket.
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Sow under cloches or fleece, or in a coldframe, from early March to early April. Start them off early to get the best crop.
Use early, mid-season and late cultivars, to provide a long cropping season.
For an early crop, sow in a greenhouse in small pots or modular trays in February, for harvesting from August.
Brussels are traditionally sown in a separate seed bed, rather than on the main veg plot, then transplanted in early summer, once more space is available.
Sow seeds thinly, 13mm (½in) deep, in rows 15cm (6in) apart. Thin seedlings to 7.5cm (3in) apart once they are large enough to handle.
Grow in pots if clubroot is a problem.
From mid-May to early June, when the young plants are 10–15cm (4–6in) tall and have seven true leaves, transplant them to their final growing position:
Choose a sunny site, sheltered from strong winds
Improve the soil by adding up to two bucketfuls of well-rotted manure per square metre/yard, and a high potassium general fertiliser, such as Vitax Q4, at a rate of three handfuls per square metre/yard.
Water the plants well before moving them, and again afterwards
Space them 60cm (2ft) apart, with 75cm (2½ft) between rows
Water the plants regularly until they have settled in. Then water in dry weather, repeating every 10–14 days.
In July, apply a top-dressing of nitrogen-rich fertiliser, such as dried poultry manure pellets (150g/5oz per square metre/yard).
In September, mound soil around the base of the stems, to provide extra support.
Roots become swollen and distorted, and leaves become pale and yellow and wilt easily. Plants may die.
Improve drainage and add lime to make soil more alkaline. Do not grow in affected soil.
Birds, especially pigeons, can cause an array of problems including eating seedlings, buds, leaves, fruit and vegetables.
Protect the plants from birds by covering them with netting or fleece. Scarecrows and bird-scaring mechanisms work for a while, but the most reliable method of protection is to cover plants with horticultural fleece or mesh.
Cabbage root fly
White larvae approximately 5cm (2in) long, feed on the roots just below the soil surface, stunting growth and causing plants to wilt and die.
Grow under insect-proof mesh or horticultural fleece. Seedlings are most vulnerable.
A number of caterpillars will feed on brassicas, but the most common are those of cabbage white butterflies. You will usually see the caterpillars, if not, you will see the holes they make in the leaves. They will also bore into the heart of cabbages.
In mild attacks, or if you have only a few plants, you may be able to pick the caterpillars off. Insect-proof mesh or fine netting (5-7mm mesh) can prevent egg-laying.
Early varieties can be harvested from August. With later cultivars, the flavour is improved once the sprouts have been frosted.
Start picking the lowest sprouts first, when they are the size of a walnut, firm and still tightly closed. Snap them off with a sharp downward tug.
At the end of the season, the sprout tops can be harvested too.
The Royal Horticultural Society is the UK’s leading gardening charity. We aim to enrich everyone’s life through plants, and make the UK a greener and more beautiful place.