How to grow Brussels sprouts

Harvesting Brussels sprouts

Brussels sprouts are a popular vegetable in the cabbage (Brassica) family, and a staple part of the traditional Christmas lunch. Named after their popularity in Belgium, they are an excellent source of vitamins C and D, along with folic acid and dietary fibre. Brussels sprouts also contain anti-cancer compounds called glucosinolates, which makes them a ‘super food’.

Brussels sprouts are slow growing, and can take up to 31 weeks to produce a crop. However, they crop from autumn through to spring, providing a valuable source of food in winter, when little else is available.

Sow seeds in spring and plant out into fertile soil after all risk of frost has passed. Water regularly, feed with an organic nitrogen-rich fertiliser and stake in autumn to prevent wind rock. Harvest the sprouts as and when they are produced.

Where to grow Brussels sprouts

Brussels sprouts do best in a moist but well-drained, fertile soil, ideally which has been enhanced with well-rotted manure or compost. Grow in full sun for best results.

How to plant Brussels sprouts

For a successive harvest, sow Brussels sprouts seeds every fortnight from March to May, in pots or modular seed trays – one seed per module or small pot – and keep them in an unheated greenhouse or cold frame. After around four weeks (or when seedlings are large enough to handle), transplant them into individual pots of peat-free compost. Then, from May onwards, when plants are 10-15cm tall, harden them off before planting out into well-prepared soil enriched with well-rotted horse manure. Space plants 60cm apart with 75cm between rows. Firm the soil around the plants thoroughly, as Brussels sprouts do best in firm soil. Water well and continue to water throughout the growing season, particularly in periods of drought. If cabbage root fly is a problem in your area, fix cabbage collars around the base of the stems.

How to care for Brussels sprouts

Staking Brussels sprouts

Feed fortnightly with an organic nitrogen-rich fertiliser. Prevent weeds from competing with the plants by hoeing regularly. Stake plants in autumn and earth up around the roots to prevent them rocking in high winds. Remove any yellowing leaves from the plants as they can harbour disease.

Growing Brussels sprouts: pests and diseases

Large white caterpillar on brassica leaf

Blueish leaves that wilt in sunlight: are likely to be cabbage root fly. Look out for white maggots around the roots. Use cabbage collars around the base of the stems to prevent further attack.

Caterpillars eating the leaves: these are most likely the larvae of the large and small white butterfly (known as cabbage white butterflies). Gently transfer caterpillars to a sacrificial crop of nasturtiums, which are in the same family and will be readily eaten by both butterfly species.

Stunted growth: this is most likely caused by clubroot, a fungal disease that thrives in acid soil and can remain in the soil for several years, reinfecting newly planted plants. Adding ground limestone or calcified seaweed can help prevent its spread, however if you do find clubroot in your garden or allotment it’s best to avoid growing brassicas for up to nine years.

Blown sprouts: these are open sprouts as opposed to the tight ‘buttons’ you expect. Causes include poor and infirm soil.

How to harvest Brussels sprouts

Harvesting Brussels sprouts

Brussels spouts ripen from the base of the stalk, so harvest them from the bottom as and when they are ready to pick. You can also cut the whole stalk as this will ensure the sprouts will keep for longer.

Advice on buying Brussels sprouts

There’s a huge variety of Brussels sprouts to choose from, with early varieties ready from August and later varieties cropping until March
Ensure you have the right growing conditions for Brussels sprouts, and remember they need a rich, fertile soil to grow well